From 8bc84b28205606f3fc8f1e3231fdacca42a99c50 Mon Sep 17 00:00:00 2001
From: Tpt <thomaspt@hotmail.fr>
Date: Tue, 4 Aug 2020 15:34:46 +0200
Subject: [PATCH] Adds borrowed data structures for RDF terms

---
 js/src/model.rs                   |   2 +-
 js/src/store.rs                   |  18 +-
 lib/Cargo.toml                    |   1 -
 lib/src/io/write.rs               |  10 +-
 lib/src/lib.rs                    |   2 +-
 lib/src/model/blank_node.rs       | 207 ++++++++--
 lib/src/model/literal.rs          | 300 +++++++++++---
 lib/src/model/mod.rs              |  11 +-
 lib/src/model/named_node.rs       | 119 +++++-
 lib/src/model/triple.rs           | 663 ++++++++++++++++++++++++++----
 lib/src/model/vocab.rs            | 386 +++++++++--------
 lib/src/sparql/algebra.rs         |  12 +
 lib/src/sparql/eval.rs            |   9 +-
 lib/src/sparql/parser.rs          |  34 +-
 lib/src/sparql/plan_builder.rs    |  13 +-
 lib/src/store/memory.rs           |  46 +--
 lib/src/store/mod.rs              |  73 +---
 lib/src/store/numeric_encoder.rs  | 101 ++---
 lib/src/store/rocksdb.rs          | 106 +++--
 lib/src/store/sled.rs             | 106 +++--
 python/src/memory_store.rs        |   8 +-
 python/src/model.rs               |   2 +-
 python/src/sled_store.rs          |   8 +-
 testsuite/Cargo.toml              |   1 -
 testsuite/src/manifest.rs         |  97 ++---
 testsuite/src/sparql_evaluator.rs | 182 ++++----
 testsuite/src/vocab.rs            | 115 +++---
 wikibase/src/loader.rs            |   8 +-
 28 files changed, 1781 insertions(+), 859 deletions(-)

diff --git a/js/src/model.rs b/js/src/model.rs
index 668ae963..a15532b1 100644
--- a/js/src/model.rs
+++ b/js/src/model.rs
@@ -246,7 +246,7 @@ impl JsLiteral {
 
     #[wasm_bindgen(getter)]
     pub fn datatype(&self) -> JsNamedNode {
-        self.inner.datatype().clone().into()
+        self.inner.datatype().into_owned().into()
     }
 
     pub fn equals(&self, other: &JsValue) -> bool {
diff --git a/js/src/store.rs b/js/src/store.rs
index 36324ee6..991c6618 100644
--- a/js/src/store.rs
+++ b/js/src/store.rs
@@ -3,10 +3,10 @@ use crate::model::*;
 use crate::utils::to_err;
 use js_sys::{Array, Map};
 use oxigraph::io::{DatasetFormat, GraphFormat};
-use oxigraph::model::GraphName;
+use oxigraph::model::*;
 use oxigraph::sparql::{QueryOptions, QueryResult};
 use oxigraph::MemoryStore;
-use std::convert::TryInto;
+use std::convert::{TryFrom, TryInto};
 use std::io::Cursor;
 use wasm_bindgen::prelude::*;
 
@@ -74,25 +74,29 @@ impl JsMemoryStore {
                 } else {
                     None
                 }
-                .as_ref(),
+                .as_ref()
+                .map(|t: &NamedOrBlankNode| t.into()),
                 if let Some(predicate) = self.from_js.to_optional_term(predicate)? {
-                    Some(predicate.try_into()?)
+                    Some(NamedNode::try_from(predicate)?)
                 } else {
                     None
                 }
-                .as_ref(),
+                .as_ref()
+                .map(|t: &NamedNode| t.into()),
                 if let Some(object) = self.from_js.to_optional_term(object)? {
                     Some(object.try_into()?)
                 } else {
                     None
                 }
-                .as_ref(),
+                .as_ref()
+                .map(|t: &Term| t.into()),
                 if let Some(graph_name) = self.from_js.to_optional_term(graph_name)? {
                     Some(graph_name.try_into()?)
                 } else {
                     None
                 }
-                .as_ref(),
+                .as_ref()
+                .map(|t: &GraphName| t.into()),
             )
             .map(|v| JsQuad::from(v).into())
             .collect::<Vec<_>>()
diff --git a/lib/Cargo.toml b/lib/Cargo.toml
index 48f340f7..cbb1ed00 100644
--- a/lib/Cargo.toml
+++ b/lib/Cargo.toml
@@ -16,7 +16,6 @@ edition = "2018"
 all-features = true
 
 [dependencies]
-lazy_static = "1"
 rocksdb = { version = "0.14", optional = true }
 sled = { version = "0.34", optional = true }
 quick-xml = "0.18"
diff --git a/lib/src/io/write.rs b/lib/src/io/write.rs
index 09cedbf0..3a202bd2 100644
--- a/lib/src/io/write.rs
+++ b/lib/src/io/write.rs
@@ -88,7 +88,8 @@ enum TripleWriterKind<W: Write> {
 }
 
 impl<W: Write> TripleWriter<W> {
-    pub fn write(&mut self, triple: &Triple) -> Result<(), io::Error> {
+    pub fn write<'a>(&mut self, triple: impl Into<TripleRef<'a>>) -> Result<(), io::Error> {
+        let triple = triple.into();
         match &mut self.formatter {
             TripleWriterKind::NTriples(formatter) => formatter.format(&triple.into())?,
             TripleWriterKind::Turtle(formatter) => formatter.format(&triple.into())?,
@@ -187,10 +188,11 @@ enum QuadWriterKind<W: Write> {
 }
 
 impl<W: Write> QuadWriter<W> {
-    pub fn write(&mut self, triple: &Quad) -> Result<(), io::Error> {
+    pub fn write<'a>(&mut self, quad: impl Into<QuadRef<'a>>) -> Result<(), io::Error> {
+        let quad = quad.into();
         match &mut self.formatter {
-            QuadWriterKind::NQuads(formatter) => formatter.format(&triple.into())?,
-            QuadWriterKind::TriG(formatter) => formatter.format(&triple.into())?,
+            QuadWriterKind::NQuads(formatter) => formatter.format(&quad.into())?,
+            QuadWriterKind::TriG(formatter) => formatter.format(&quad.into())?,
         }
         Ok(())
     }
diff --git a/lib/src/lib.rs b/lib/src/lib.rs
index b7d893b8..d6e2b965 100644
--- a/lib/src/lib.rs
+++ b/lib/src/lib.rs
@@ -27,7 +27,7 @@
 //! store.insert(quad.clone());
 //!
 //! // quad filter
-//! let results: Vec<Quad> = store.quads_for_pattern(Some(&ex.clone().into()), None, None, None).collect();
+//! let results: Vec<Quad> = store.quads_for_pattern(Some(ex.as_ref().into()), None, None, None).collect();
 //! assert_eq!(vec![quad], results);
 //!
 //! // SPARQL query
diff --git a/lib/src/model/blank_node.rs b/lib/src/model/blank_node.rs
index 59081e9b..5c395f76 100644
--- a/lib/src/model/blank_node.rs
+++ b/lib/src/model/blank_node.rs
@@ -5,7 +5,7 @@ use std::fmt;
 use std::io::Write;
 use std::str;
 
-/// An RDF [blank node](https://www.w3.org/TR/rdf11-concepts/#dfn-blank-node).
+/// An owned RDF [blank node](https://www.w3.org/TR/rdf11-concepts/#dfn-blank-node).
 ///
 /// The common way to create a new blank node is to use the `BlankNode::default` trait method.
 ///
@@ -28,7 +28,7 @@ pub struct BlankNode(BlankNodeContent);
 #[derive(PartialEq, Eq, Debug, Clone, Hash)]
 enum BlankNodeContent {
     Named(String),
-    Anonymous { id: u128, str: [u8; 32] },
+    Anonymous { id: u128, str: IdStr },
 }
 
 impl BlankNode {
@@ -52,13 +52,8 @@ impl BlankNode {
     /// Except if you really know what you do, you should use [`new`](#method.new).
     pub fn new_unchecked(id: impl Into<String>) -> Self {
         let id = id.into();
-        if let Ok(numerical_id) = u128::from_str_radix(&id, 16) {
-            let result = Self::new_from_unique_id(numerical_id);
-            if result.as_str() == id {
-                result
-            } else {
-                Self(BlankNodeContent::Named(id))
-            }
+        if let Some(numerical_id) = to_integer_id(&id) {
+            Self::new_from_unique_id(numerical_id)
         } else {
             Self(BlankNodeContent::Named(id))
         }
@@ -69,19 +64,17 @@ impl BlankNode {
     /// In most cases, it is much more convenient to create a blank node using `BlankNode::default()`.
     pub fn new_from_unique_id(id: impl Into<u128>) -> Self {
         let id = id.into();
-        let mut str = [0; 32];
-        write!(&mut str[..], "{:x}", id).unwrap();
-        Self(BlankNodeContent::Anonymous { id, str })
+        Self(BlankNodeContent::Anonymous {
+            id,
+            str: IdStr::new(id),
+        })
     }
 
     /// Returns the underlying ID of this blank node
     pub fn as_str(&self) -> &str {
         match &self.0 {
             BlankNodeContent::Named(id) => id,
-            BlankNodeContent::Anonymous { str, .. } => {
-                let len = str.iter().position(|x| x == &0).unwrap_or(32);
-                str::from_utf8(&str[..len]).unwrap()
-            }
+            BlankNodeContent::Anonymous { str, .. } => str.as_str(),
         }
     }
 
@@ -89,25 +82,24 @@ impl BlankNode {
     pub fn into_string(self) -> String {
         match self.0 {
             BlankNodeContent::Named(id) => id,
-            BlankNodeContent::Anonymous { str, .. } => {
-                let len = str.iter().position(|x| x == &0).unwrap_or(32);
-                str::from_utf8(&str[..len]).unwrap().to_owned()
-            }
+            BlankNodeContent::Anonymous { str, .. } => str.as_str().to_owned(),
         }
     }
 
-    /// Returns the internal numerical ID of this blank node, if it exists
-    pub(crate) fn id(&self) -> Option<u128> {
-        match self.0 {
-            BlankNodeContent::Named(_) => None,
-            BlankNodeContent::Anonymous { id, .. } => Some(id),
-        }
+    pub fn as_ref(&self) -> BlankNodeRef<'_> {
+        BlankNodeRef(match &self.0 {
+            BlankNodeContent::Named(id) => BlankNodeRefContent::Named(id.as_str()),
+            BlankNodeContent::Anonymous { id, str } => BlankNodeRefContent::Anonymous {
+                id: *id,
+                str: str.as_str(),
+            },
+        })
     }
 }
 
 impl fmt::Display for BlankNode {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        rio::BlankNode::from(self).fmt(f)
+        self.as_ref().fmt(f)
     }
 }
 
@@ -118,12 +110,140 @@ impl Default for BlankNode {
     }
 }
 
-impl<'a> From<&'a BlankNode> for rio::BlankNode<'a> {
+/// A borrowed RDF [blank node](https://www.w3.org/TR/rdf11-concepts/#dfn-blank-node).
+///
+/// The common way to create a new blank node is to use the `BlankNode::default` trait method.
+///
+/// It is also possible to create a blank node from a blank node identifier using the `BlankNodeRef::new` method.
+/// The blank node identifier must be valid according to N-Triples, Turtle and SPARQL grammars.
+///
+/// The default string formatter is returning a N-Triples, Turtle and SPARQL compatible representation:
+/// ```
+/// use oxigraph::model::BlankNodeRef;
+///
+/// assert_eq!(
+///     "_:a122",
+///     BlankNodeRef::new("a122")?.to_string()
+/// );
+/// # Result::<_,oxigraph::model::BlankNodeIdParseError>::Ok(())
+/// ```
+#[derive(Eq, PartialEq, Debug, Clone, Copy, Hash)]
+pub struct BlankNodeRef<'a>(BlankNodeRefContent<'a>);
+
+#[derive(PartialEq, Eq, Debug, Clone, Copy, Hash)]
+enum BlankNodeRefContent<'a> {
+    Named(&'a str),
+    Anonymous { id: u128, str: &'a str },
+}
+
+impl<'a> BlankNodeRef<'a> {
+    /// Creates a blank node from a unique identifier.
+    ///
+    /// The blank node identifier must be valid according to N-Triples, Turtle and SPARQL grammars.
+    ///
+    /// In most cases, it is much more convenient to create a blank node using `BlankNode::default()`.
+    /// `BlankNode::default()` creates a random ID that could be easily inlined by Oxigraph stores.
+    pub fn new(id: &'a str) -> Result<Self, BlankNodeIdParseError> {
+        validate_blank_node_identifier(id)?;
+        Ok(Self::new_unchecked(id))
+    }
+
+    /// Creates a blank node from a unique identifier without validation.
+    ///
+    /// It is the caller's responsibility to ensure that `id` is a valid blank node identifier
+    /// according to N-Triples, Turtle and SPARQL grammars.
+    ///
+    /// Except if you really know what you do, you should use [`new`](#method.new).
+    pub fn new_unchecked(id: &'a str) -> Self {
+        if let Some(numerical_id) = to_integer_id(id) {
+            Self(BlankNodeRefContent::Anonymous {
+                id: numerical_id,
+                str: id,
+            })
+        } else {
+            Self(BlankNodeRefContent::Named(id))
+        }
+    }
+
+    /// Returns the underlying ID of this blank node
+    pub fn as_str(self) -> &'a str {
+        match self.0 {
+            BlankNodeRefContent::Named(id) => id,
+            BlankNodeRefContent::Anonymous { str, .. } => str,
+        }
+    }
+
+    /// Returns the internal numerical ID of this blank node, if it exists
+    pub(crate) fn id(&self) -> Option<u128> {
+        match self.0 {
+            BlankNodeRefContent::Named(_) => None,
+            BlankNodeRefContent::Anonymous { id, .. } => Some(id),
+        }
+    }
+
+    pub fn into_owned(self) -> BlankNode {
+        BlankNode(match self.0 {
+            BlankNodeRefContent::Named(id) => BlankNodeContent::Named(id.to_owned()),
+            BlankNodeRefContent::Anonymous { id, .. } => BlankNodeContent::Anonymous {
+                id,
+                str: IdStr::new(id),
+            },
+        })
+    }
+}
+
+impl fmt::Display for BlankNodeRef<'_> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        rio::BlankNode::from(*self).fmt(f)
+    }
+}
+
+impl<'a> From<&'a BlankNode> for BlankNodeRef<'a> {
     fn from(node: &'a BlankNode) -> Self {
+        node.as_ref()
+    }
+}
+
+impl<'a> From<BlankNodeRef<'a>> for BlankNode {
+    fn from(node: BlankNodeRef<'a>) -> Self {
+        node.into_owned()
+    }
+}
+
+impl<'a> From<BlankNodeRef<'a>> for rio::BlankNode<'a> {
+    fn from(node: BlankNodeRef<'a>) -> Self {
         rio::BlankNode { id: node.as_str() }
     }
 }
 
+impl PartialEq<BlankNode> for BlankNodeRef<'_> {
+    fn eq(&self, other: &BlankNode) -> bool {
+        *self == other.as_ref()
+    }
+}
+
+impl PartialEq<BlankNodeRef<'_>> for BlankNode {
+    fn eq(&self, other: &BlankNodeRef<'_>) -> bool {
+        self.as_ref() == *other
+    }
+}
+
+#[derive(PartialEq, Eq, Debug, Clone, Hash)]
+struct IdStr([u8; 32]);
+
+impl IdStr {
+    fn new(id: u128) -> Self {
+        let mut str = [0; 32];
+        write!(&mut str[..], "{:x}", id).unwrap();
+        Self(str)
+    }
+
+    fn as_str(&self) -> &str {
+        let len = self.0.iter().position(|x| x == &0).unwrap_or(32);
+        str::from_utf8(&self.0[..len]).unwrap()
+    }
+}
+
 fn validate_blank_node_identifier(id: &str) -> Result<(), BlankNodeIdParseError> {
     let mut chars = id.chars();
     let front = chars.next().ok_or(BlankNodeIdParseError {})?;
@@ -183,6 +303,25 @@ fn validate_blank_node_identifier(id: &str) -> Result<(), BlankNodeIdParseError>
     }
 }
 
+fn to_integer_id(id: &str) -> Option<u128> {
+    let digits = id.as_bytes();
+    let mut value: u128 = 0;
+    if let None | Some(b'0') = digits.first() {
+        return None; // No empty string or leading zeros
+    }
+    for digit in digits {
+        value = value.checked_mul(16)?.checked_add(
+            match *digit {
+                b'0'..=b'9' => digit - b'0',
+                b'a'..=b'f' => digit - b'a' + 10,
+                _ => return None,
+            }
+            .into(),
+        )?;
+    }
+    Some(value)
+}
+
 /// An error raised during `BlankNode` validation.
 #[allow(missing_copy_implementations)]
 #[derive(Debug)]
@@ -234,4 +373,16 @@ mod test {
             BlankNode::new_from_unique_id(0x100a_u128)
         );
     }
+
+    #[test]
+    fn test_equals() {
+        assert_eq!(
+            BlankNode::new("100a").unwrap(),
+            BlankNodeRef::new("100a").unwrap()
+        );
+        assert_eq!(
+            BlankNode::new("zzz").unwrap(),
+            BlankNodeRef::new("zzz").unwrap()
+        );
+    }
 }
diff --git a/lib/src/model/literal.rs b/lib/src/model/literal.rs
index b56b87c7..5d340a27 100644
--- a/lib/src/model/literal.rs
+++ b/lib/src/model/literal.rs
@@ -2,13 +2,14 @@ use crate::model::named_node::NamedNode;
 use crate::model::vocab::rdf;
 use crate::model::vocab::xsd;
 use crate::model::xsd::*;
+use crate::model::NamedNodeRef;
 use oxilangtag::{LanguageTag, LanguageTagParseError};
 use rio_api::model as rio;
 use std::borrow::Cow;
 use std::fmt;
 use std::option::Option;
 
-/// An RDF [literal](https://www.w3.org/TR/rdf11-concepts/#dfn-literal)
+/// An owned RDF [literal](https://www.w3.org/TR/rdf11-concepts/#dfn-literal)
 ///
 /// The default string formatter is returning a N-Triples, Turtle and SPARQL compatible representation:
 /// ```
@@ -23,7 +24,7 @@ use std::option::Option;
 ///
 /// assert_eq!(
 ///     "\"1999-01-01\"^^<http://www.w3.org/2001/XMLSchema#date>",
-///     Literal::new_typed_literal("1999-01-01", xsd::DATE.clone()).to_string()
+///     Literal::new_typed_literal("1999-01-01", xsd::DATE).to_string()
 /// );
 ///
 /// assert_eq!(
@@ -52,7 +53,7 @@ impl Literal {
     pub fn new_typed_literal(value: impl Into<String>, datatype: impl Into<NamedNode>) -> Self {
         let value = value.into();
         let datatype = datatype.into();
-        Literal(if datatype == *xsd::STRING {
+        Literal(if datatype == xsd::STRING {
             LiteralContent::String(value)
         } else {
             LiteralContent::TypedLiteral { value, datatype }
@@ -66,10 +67,10 @@ impl Literal {
     ) -> Result<Self, LanguageTagParseError> {
         let mut language = language.into();
         language.make_ascii_lowercase();
-        Ok(Literal(LiteralContent::LanguageTaggedString {
-            value: value.into(),
-            language: LanguageTag::parse(language)?.into_inner(),
-        }))
+        Ok(Self::new_language_tagged_literal_unchecked(
+            value,
+            LanguageTag::parse(language)?.into_inner(),
+        ))
     }
 
     /// Builds an RDF [language-tagged string](https://www.w3.org/TR/rdf11-concepts/#dfn-language-tagged-string)
@@ -92,11 +93,7 @@ impl Literal {
 
     /// The literal [lexical form](https://www.w3.org/TR/rdf11-concepts/#dfn-lexical-form)
     pub fn value(&self) -> &str {
-        match &self.0 {
-            LiteralContent::String(value)
-            | LiteralContent::LanguageTaggedString { value, .. }
-            | LiteralContent::TypedLiteral { value, .. } => value,
-        }
+        self.as_ref().value()
     }
 
     /// The literal [language tag](https://www.w3.org/TR/rdf11-concepts/#dfn-language-tag) if it is a [language-tagged string](https://www.w3.org/TR/rdf11-concepts/#dfn-language-tagged-string).
@@ -104,33 +101,36 @@ impl Literal {
     /// Language tags are defined by the [BCP47](https://tools.ietf.org/html/bcp47).
     /// They are normalized to lowercase by this implementation.
     pub fn language(&self) -> Option<&str> {
-        match &self.0 {
-            LiteralContent::LanguageTaggedString { language, .. } => Some(language),
-            _ => None,
-        }
+        self.as_ref().language()
     }
 
     /// The literal [datatype](https://www.w3.org/TR/rdf11-concepts/#dfn-datatype-iri).
     ///
     /// The datatype of [language-tagged string](https://www.w3.org/TR/rdf11-concepts/#dfn-language-tagged-string) is always [rdf:langString](http://www.w3.org/1999/02/22-rdf-syntax-ns#langString).
     /// The datatype of [simple literals](https://www.w3.org/TR/rdf11-concepts/#dfn-simple-literal) is [xsd:string](http://www.w3.org/2001/XMLSchema#string).
-    pub fn datatype(&self) -> &NamedNode {
-        match &self.0 {
-            LiteralContent::String(_) => &xsd::STRING,
-            LiteralContent::LanguageTaggedString { .. } => &rdf::LANG_STRING,
-            LiteralContent::TypedLiteral { datatype, .. } => datatype,
-        }
+    pub fn datatype(&self) -> NamedNodeRef<'_> {
+        self.as_ref().datatype()
     }
 
-    /// Checks if this lieteral could be seen as an RDF 1.0 [plain literal](https://www.w3.org/TR/rdf-concepts/#dfn-plain-literal).
+    /// Checks if this literal could be seen as an RDF 1.0 [plain literal](https://www.w3.org/TR/rdf-concepts/#dfn-plain-literal).
     ///
     /// It returns true if the literal is a [language-tagged string](https://www.w3.org/TR/rdf11-concepts/#dfn-language-tagged-string)
     /// or has the datatype [xsd:string](http://www.w3.org/2001/XMLSchema#string).
     pub fn is_plain(&self) -> bool {
-        match self.0 {
-            LiteralContent::String(_) | LiteralContent::LanguageTaggedString { .. } => true,
-            _ => false,
-        }
+        self.as_ref().is_plain()
+    }
+
+    pub fn as_ref(&self) -> LiteralRef<'_> {
+        LiteralRef(match &self.0 {
+            LiteralContent::String(value) => LiteralRefContent::String(value),
+            LiteralContent::LanguageTaggedString { value, language } => {
+                LiteralRefContent::LanguageTaggedString { value, language }
+            }
+            LiteralContent::TypedLiteral { value, datatype } => LiteralRefContent::TypedLiteral {
+                value,
+                datatype: datatype.as_ref(),
+            },
+        })
     }
 
     /// Extract components from this literal
@@ -147,7 +147,7 @@ impl Literal {
 
 impl fmt::Display for Literal {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        rio::Literal::from(self).fmt(f)
+        self.as_ref().fmt(f)
     }
 }
 
@@ -173,7 +173,7 @@ impl From<bool> for Literal {
     fn from(value: bool) -> Self {
         Literal(LiteralContent::TypedLiteral {
             value: value.to_string(),
-            datatype: xsd::BOOLEAN.clone(),
+            datatype: xsd::BOOLEAN.into(),
         })
     }
 }
@@ -182,7 +182,7 @@ impl From<i128> for Literal {
     fn from(value: i128) -> Self {
         Literal(LiteralContent::TypedLiteral {
             value: value.to_string(),
-            datatype: xsd::INTEGER.clone(),
+            datatype: xsd::INTEGER.into(),
         })
     }
 }
@@ -191,7 +191,7 @@ impl From<i64> for Literal {
     fn from(value: i64) -> Self {
         Literal(LiteralContent::TypedLiteral {
             value: value.to_string(),
-            datatype: xsd::INTEGER.clone(),
+            datatype: xsd::INTEGER.into(),
         })
     }
 }
@@ -200,7 +200,7 @@ impl From<i32> for Literal {
     fn from(value: i32) -> Self {
         Literal(LiteralContent::TypedLiteral {
             value: value.to_string(),
-            datatype: xsd::INTEGER.clone(),
+            datatype: xsd::INTEGER.into(),
         })
     }
 }
@@ -209,7 +209,7 @@ impl From<i16> for Literal {
     fn from(value: i16) -> Self {
         Literal(LiteralContent::TypedLiteral {
             value: value.to_string(),
-            datatype: xsd::INTEGER.clone(),
+            datatype: xsd::INTEGER.into(),
         })
     }
 }
@@ -218,7 +218,7 @@ impl From<u64> for Literal {
     fn from(value: u64) -> Self {
         Literal(LiteralContent::TypedLiteral {
             value: value.to_string(),
-            datatype: xsd::INTEGER.clone(),
+            datatype: xsd::INTEGER.into(),
         })
     }
 }
@@ -227,7 +227,7 @@ impl From<u32> for Literal {
     fn from(value: u32) -> Self {
         Literal(LiteralContent::TypedLiteral {
             value: value.to_string(),
-            datatype: xsd::INTEGER.clone(),
+            datatype: xsd::INTEGER.into(),
         })
     }
 }
@@ -236,7 +236,7 @@ impl From<u16> for Literal {
     fn from(value: u16) -> Self {
         Literal(LiteralContent::TypedLiteral {
             value: value.to_string(),
-            datatype: xsd::INTEGER.clone(),
+            datatype: xsd::INTEGER.into(),
         })
     }
 }
@@ -245,7 +245,7 @@ impl From<f32> for Literal {
     fn from(value: f32) -> Self {
         Literal(LiteralContent::TypedLiteral {
             value: value.to_string(),
-            datatype: xsd::FLOAT.clone(),
+            datatype: xsd::FLOAT.into(),
         })
     }
 }
@@ -254,7 +254,7 @@ impl From<f64> for Literal {
     fn from(value: f64) -> Self {
         Literal(LiteralContent::TypedLiteral {
             value: value.to_string(),
-            datatype: xsd::DOUBLE.clone(),
+            datatype: xsd::DOUBLE.into(),
         })
     }
 }
@@ -263,7 +263,7 @@ impl From<Decimal> for Literal {
     fn from(value: Decimal) -> Self {
         Literal(LiteralContent::TypedLiteral {
             value: value.to_string(),
-            datatype: xsd::DECIMAL.clone(),
+            datatype: xsd::DECIMAL.into(),
         })
     }
 }
@@ -272,7 +272,7 @@ impl From<Date> for Literal {
     fn from(value: Date) -> Self {
         Literal(LiteralContent::TypedLiteral {
             value: value.to_string(),
-            datatype: xsd::DATE.clone(),
+            datatype: xsd::DATE.into(),
         })
     }
 }
@@ -281,7 +281,7 @@ impl From<Time> for Literal {
     fn from(value: Time) -> Self {
         Literal(LiteralContent::TypedLiteral {
             value: value.to_string(),
-            datatype: xsd::TIME.clone(),
+            datatype: xsd::TIME.into(),
         })
     }
 }
@@ -290,7 +290,7 @@ impl From<DateTime> for Literal {
     fn from(value: DateTime) -> Self {
         Literal(LiteralContent::TypedLiteral {
             value: value.to_string(),
-            datatype: xsd::DATE_TIME.clone(),
+            datatype: xsd::DATE_TIME.into(),
         })
     }
 }
@@ -299,7 +299,7 @@ impl From<Duration> for Literal {
     fn from(value: Duration) -> Self {
         Literal(LiteralContent::TypedLiteral {
             value: value.to_string(),
-            datatype: xsd::DURATION.clone(),
+            datatype: xsd::DURATION.into(),
         })
     }
 }
@@ -308,7 +308,7 @@ impl From<YearMonthDuration> for Literal {
     fn from(value: YearMonthDuration) -> Self {
         Literal(LiteralContent::TypedLiteral {
             value: value.to_string(),
-            datatype: xsd::YEAR_MONTH_DURATION.clone(),
+            datatype: xsd::YEAR_MONTH_DURATION.into(),
         })
     }
 }
@@ -316,32 +316,196 @@ impl From<DayTimeDuration> for Literal {
     fn from(value: DayTimeDuration) -> Self {
         Literal(LiteralContent::TypedLiteral {
             value: value.to_string(),
-            datatype: xsd::DAY_TIME_DURATION.clone(),
+            datatype: xsd::DAY_TIME_DURATION.into(),
         })
     }
 }
 
-impl<'a> From<&'a Literal> for rio::Literal<'a> {
-    fn from(literal: &'a Literal) -> Self {
-        if literal.is_plain() {
-            literal.language().map_or_else(
-                || rio::Literal::Simple {
-                    value: literal.value(),
-                },
-                |lang| rio::Literal::LanguageTaggedString {
-                    value: literal.value(),
-                    language: lang,
-                },
-            )
+/// A borrowed RDF [literal](https://www.w3.org/TR/rdf11-concepts/#dfn-literal)
+///
+/// The default string formatter is returning a N-Triples, Turtle and SPARQL compatible representation:
+/// ```
+/// # use oxilangtag::LanguageTagParseError;
+/// use oxigraph::model::LiteralRef;
+/// use oxigraph::model::vocab::xsd;
+///
+/// assert_eq!(
+///     "\"foo\\nbar\"",
+///     LiteralRef::new_simple_literal("foo\nbar").to_string()
+/// );
+///
+/// assert_eq!(
+///     "\"1999-01-01\"^^<http://www.w3.org/2001/XMLSchema#date>",
+///     LiteralRef::new_typed_literal("1999-01-01", xsd::DATE).to_string()
+/// );
+/// # Result::<(), LanguageTagParseError>::Ok(())
+/// ```
+#[derive(Eq, PartialEq, Debug, Clone, Copy, Hash)]
+pub struct LiteralRef<'a>(LiteralRefContent<'a>);
+
+#[derive(PartialEq, Eq, Debug, Clone, Copy, Hash)]
+enum LiteralRefContent<'a> {
+    String(&'a str),
+    LanguageTaggedString {
+        value: &'a str,
+        language: &'a str,
+    },
+    TypedLiteral {
+        value: &'a str,
+        datatype: NamedNodeRef<'a>,
+    },
+}
+
+impl<'a> LiteralRef<'a> {
+    /// Builds an RDF [simple literal](https://www.w3.org/TR/rdf11-concepts/#dfn-simple-literal)
+    pub fn new_simple_literal(value: &'a str) -> Self {
+        LiteralRef(LiteralRefContent::String(value))
+    }
+
+    /// Builds an RDF [literal](https://www.w3.org/TR/rdf11-concepts/#dfn-literal) with a [datatype](https://www.w3.org/TR/rdf11-concepts/#dfn-datatype-iri)
+    pub fn new_typed_literal(value: &'a str, datatype: impl Into<NamedNodeRef<'a>>) -> Self {
+        let datatype = datatype.into();
+        LiteralRef(if datatype == xsd::STRING {
+            LiteralRefContent::String(value)
         } else {
-            rio::Literal::Typed {
-                value: literal.value(),
-                datatype: literal.datatype().into(),
+            LiteralRefContent::TypedLiteral { value, datatype }
+        })
+    }
+
+    /// Builds an RDF [language-tagged string](https://www.w3.org/TR/rdf11-concepts/#dfn-language-tagged-string)
+    ///
+    /// It is the responsibility of the caller to check that `language`
+    /// is valid [BCP47](https://tools.ietf.org/html/bcp47) language tag,
+    /// and is lowercase.
+    ///
+    /// Except if you really know what you do,
+    /// you should use [`new_language_tagged_literal`](#method.new_language_tagged_literal).
+    pub fn new_language_tagged_literal_unchecked(value: &'a str, language: &'a str) -> Self {
+        LiteralRef(LiteralRefContent::LanguageTaggedString { value, language })
+    }
+
+    /// The literal [lexical form](https://www.w3.org/TR/rdf11-concepts/#dfn-lexical-form)
+    pub fn value(self) -> &'a str {
+        match self.0 {
+            LiteralRefContent::String(value)
+            | LiteralRefContent::LanguageTaggedString { value, .. }
+            | LiteralRefContent::TypedLiteral { value, .. } => value,
+        }
+    }
+
+    /// The literal [language tag](https://www.w3.org/TR/rdf11-concepts/#dfn-language-tag) if it is a [language-tagged string](https://www.w3.org/TR/rdf11-concepts/#dfn-language-tagged-string).
+    ///
+    /// Language tags are defined by the [BCP47](https://tools.ietf.org/html/bcp47).
+    /// They are normalized to lowercase by this implementation.
+    pub fn language(self) -> Option<&'a str> {
+        match self.0 {
+            LiteralRefContent::LanguageTaggedString { language, .. } => Some(language),
+            _ => None,
+        }
+    }
+
+    /// The literal [datatype](https://www.w3.org/TR/rdf11-concepts/#dfn-datatype-iri).
+    ///
+    /// The datatype of [language-tagged string](https://www.w3.org/TR/rdf11-concepts/#dfn-language-tagged-string) is always [rdf:langString](http://www.w3.org/1999/02/22-rdf-syntax-ns#langString).
+    /// The datatype of [simple literals](https://www.w3.org/TR/rdf11-concepts/#dfn-simple-literal) is [xsd:string](http://www.w3.org/2001/XMLSchema#string).
+    pub fn datatype(self) -> NamedNodeRef<'a> {
+        match self.0 {
+            LiteralRefContent::String(_) => xsd::STRING,
+            LiteralRefContent::LanguageTaggedString { .. } => rdf::LANG_STRING,
+            LiteralRefContent::TypedLiteral { datatype, .. } => datatype,
+        }
+    }
+
+    /// Checks if this literal could be seen as an RDF 1.0 [plain literal](https://www.w3.org/TR/rdf-concepts/#dfn-plain-literal).
+    ///
+    /// It returns true if the literal is a [language-tagged string](https://www.w3.org/TR/rdf11-concepts/#dfn-language-tagged-string)
+    /// or has the datatype [xsd:string](http://www.w3.org/2001/XMLSchema#string).
+    pub fn is_plain(self) -> bool {
+        match self.0 {
+            LiteralRefContent::String(_) | LiteralRefContent::LanguageTaggedString { .. } => true,
+            _ => false,
+        }
+    }
+
+    pub fn into_owned(self) -> Literal {
+        Literal(match self.0 {
+            LiteralRefContent::String(value) => LiteralContent::String(value.to_owned()),
+            LiteralRefContent::LanguageTaggedString { value, language } => {
+                LiteralContent::LanguageTaggedString {
+                    value: value.to_owned(),
+                    language: language.to_owned(),
+                }
+            }
+            LiteralRefContent::TypedLiteral { value, datatype } => LiteralContent::TypedLiteral {
+                value: value.to_owned(),
+                datatype: datatype.into_owned(),
+            },
+        })
+    }
+
+    /// Extract components from this literal
+    pub fn destruct(self) -> (&'a str, Option<NamedNodeRef<'a>>, Option<&'a str>) {
+        match self.0 {
+            LiteralRefContent::String(s) => (s, None, None),
+            LiteralRefContent::LanguageTaggedString { value, language } => {
+                (value, None, Some(language))
             }
+            LiteralRefContent::TypedLiteral { value, datatype } => (value, Some(datatype), None),
         }
     }
 }
 
+impl fmt::Display for LiteralRef<'_> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        rio::Literal::from(*self).fmt(f)
+    }
+}
+
+impl<'a> From<&'a Literal> for LiteralRef<'a> {
+    fn from(node: &'a Literal) -> Self {
+        node.as_ref()
+    }
+}
+
+impl<'a> From<LiteralRef<'a>> for Literal {
+    fn from(node: LiteralRef<'a>) -> Self {
+        node.into_owned()
+    }
+}
+
+impl<'a> From<LiteralRef<'a>> for rio::Literal<'a> {
+    fn from(literal: LiteralRef<'a>) -> Self {
+        match literal.0 {
+            LiteralRefContent::String(value) => rio::Literal::Simple { value },
+            LiteralRefContent::LanguageTaggedString { value, language } => {
+                rio::Literal::LanguageTaggedString { value, language }
+            }
+            LiteralRefContent::TypedLiteral { value, datatype } => rio::Literal::Typed {
+                value,
+                datatype: datatype.into(),
+            },
+        }
+    }
+}
+
+impl<'a> From<&'a str> for LiteralRef<'a> {
+    fn from(value: &'a str) -> Self {
+        LiteralRef(LiteralRefContent::String(value))
+    }
+}
+
+impl PartialEq<Literal> for LiteralRef<'_> {
+    fn eq(&self, other: &Literal) -> bool {
+        *self == other.as_ref()
+    }
+}
+
+impl PartialEq<LiteralRef<'_>> for Literal {
+    fn eq(&self, other: &LiteralRef<'_>) -> bool {
+        self.as_ref() == *other
+    }
+}
+
 #[cfg(test)]
 mod test {
     use super::*;
@@ -350,7 +514,19 @@ mod test {
     fn test_simple_literal_equality() {
         assert_eq!(
             Literal::new_simple_literal("foo"),
-            Literal::new_typed_literal("foo", xsd::STRING.clone())
-        )
+            Literal::new_typed_literal("foo", xsd::STRING)
+        );
+        assert_eq!(
+            Literal::new_simple_literal("foo"),
+            LiteralRef::new_typed_literal("foo", xsd::STRING)
+        );
+        assert_eq!(
+            LiteralRef::new_simple_literal("foo"),
+            Literal::new_typed_literal("foo", xsd::STRING)
+        );
+        assert_eq!(
+            LiteralRef::new_simple_literal("foo"),
+            LiteralRef::new_typed_literal("foo", xsd::STRING)
+        );
     }
 }
diff --git a/lib/src/model/mod.rs b/lib/src/model/mod.rs
index 307c26d4..f9bd3b1c 100644
--- a/lib/src/model/mod.rs
+++ b/lib/src/model/mod.rs
@@ -9,9 +9,12 @@ mod triple;
 pub mod vocab;
 pub(crate) mod xsd;
 
-pub use crate::model::blank_node::{BlankNode, BlankNodeIdParseError};
-pub use crate::model::literal::Literal;
-pub use crate::model::named_node::NamedNode;
-pub use crate::model::triple::{GraphName, NamedOrBlankNode, Quad, Term, Triple};
+pub use crate::model::blank_node::{BlankNode, BlankNodeIdParseError, BlankNodeRef};
+pub use crate::model::literal::{Literal, LiteralRef};
+pub use crate::model::named_node::{NamedNode, NamedNodeRef};
+pub use crate::model::triple::{
+    GraphName, GraphNameRef, NamedOrBlankNode, NamedOrBlankNodeRef, Quad, QuadRef, Term, TermRef,
+    Triple, TripleRef,
+};
 pub use oxilangtag::LanguageTagParseError;
 pub use oxiri::IriParseError;
diff --git a/lib/src/model/named_node.rs b/lib/src/model/named_node.rs
index dd837f61..7c700dae 100644
--- a/lib/src/model/named_node.rs
+++ b/lib/src/model/named_node.rs
@@ -2,7 +2,7 @@ use oxiri::{Iri, IriParseError};
 use rio_api::model as rio;
 use std::fmt;
 
-/// An RDF [IRI](https://www.w3.org/TR/rdf11-concepts/#dfn-iri)
+/// An owned RDF [IRI](https://www.w3.org/TR/rdf11-concepts/#dfn-iri)
 ///
 /// The default string formatter is returning a N-Triples, Turtle and SPARQL compatible representation:
 /// ```
@@ -50,17 +50,15 @@ impl NamedNode {
     pub fn into_string(self) -> String {
         self.iri
     }
-}
 
-impl fmt::Display for NamedNode {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        rio::NamedNode::from(self).fmt(f)
+    pub fn as_ref(&self) -> NamedNodeRef<'_> {
+        NamedNodeRef::new_unchecked(&self.iri)
     }
 }
 
-impl<'a> From<&'a NamedNode> for rio::NamedNode<'a> {
-    fn from(node: &'a NamedNode) -> Self {
-        rio::NamedNode { iri: node.as_str() }
+impl fmt::Display for NamedNode {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        self.as_ref().fmt(f)
     }
 }
 
@@ -87,3 +85,108 @@ impl PartialEq<NamedNode> for &str {
         *self == other
     }
 }
+
+/// A borrowed RDF [IRI](https://www.w3.org/TR/rdf11-concepts/#dfn-iri)
+///
+/// The default string formatter is returning a N-Triples, Turtle and SPARQL compatible representation:
+/// ```
+/// use oxigraph::model::NamedNodeRef;
+///
+/// assert_eq!(
+///     "<http://example.com/foo>",
+///     NamedNodeRef::new("http://example.com/foo")?.to_string()
+/// );
+/// # Result::<_,oxigraph::model::IriParseError>::Ok(())
+/// ```
+#[derive(Eq, PartialEq, Ord, PartialOrd, Debug, Clone, Copy, Hash)]
+pub struct NamedNodeRef<'a> {
+    iri: &'a str,
+}
+
+impl<'a> NamedNodeRef<'a> {
+    /// Builds and validate an RDF [IRI](https://www.w3.org/TR/rdf11-concepts/#dfn-iri)
+    pub fn new(iri: &'a str) -> Result<Self, IriParseError> {
+        Ok(Self::new_from_iri(Iri::parse(iri)?))
+    }
+
+    pub(crate) fn new_from_iri(iri: Iri<&'a str>) -> Self {
+        Self::new_unchecked(iri.into_inner())
+    }
+
+    /// Builds an RDF [IRI](https://www.w3.org/TR/rdf11-concepts/#dfn-iri) from a string.
+    ///
+    /// It is the caller's responsibility to ensure that `iri` is a valid IRI.
+    ///
+    /// Except if you really know what you do, you should use [`parse`](#method.parse).
+    pub const fn new_unchecked(iri: &'a str) -> Self {
+        Self { iri }
+    }
+
+    pub const fn as_str(self) -> &'a str {
+        self.iri
+    }
+
+    pub fn into_owned(self) -> NamedNode {
+        NamedNode::new_unchecked(self.iri)
+    }
+}
+
+impl fmt::Display for NamedNodeRef<'_> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        rio::NamedNode::from(*self).fmt(f)
+    }
+}
+
+impl From<NamedNodeRef<'_>> for NamedNode {
+    fn from(node: NamedNodeRef<'_>) -> Self {
+        node.into_owned()
+    }
+}
+
+impl<'a> From<&'a NamedNode> for NamedNodeRef<'a> {
+    fn from(node: &'a NamedNode) -> Self {
+        node.as_ref()
+    }
+}
+
+impl<'a> From<NamedNodeRef<'a>> for rio::NamedNode<'a> {
+    fn from(node: NamedNodeRef<'a>) -> Self {
+        rio::NamedNode { iri: node.as_str() }
+    }
+}
+
+impl PartialEq<NamedNode> for NamedNodeRef<'_> {
+    fn eq(&self, other: &NamedNode) -> bool {
+        self.as_str() == other.as_str()
+    }
+}
+
+impl PartialEq<NamedNodeRef<'_>> for NamedNode {
+    fn eq(&self, other: &NamedNodeRef<'_>) -> bool {
+        self.as_str() == other.as_str()
+    }
+}
+
+impl PartialEq<str> for NamedNodeRef<'_> {
+    fn eq(&self, other: &str) -> bool {
+        self.as_str() == other
+    }
+}
+
+impl PartialEq<NamedNodeRef<'_>> for str {
+    fn eq(&self, other: &NamedNodeRef<'_>) -> bool {
+        self == other.as_str()
+    }
+}
+
+impl PartialEq<&str> for NamedNodeRef<'_> {
+    fn eq(&self, other: &&str) -> bool {
+        self == *other
+    }
+}
+
+impl PartialEq<NamedNodeRef<'_>> for &str {
+    fn eq(&self, other: &NamedNodeRef<'_>) -> bool {
+        *self == other
+    }
+}
diff --git a/lib/src/model/triple.rs b/lib/src/model/triple.rs
index dba52bcd..88604d93 100644
--- a/lib/src/model/triple.rs
+++ b/lib/src/model/triple.rs
@@ -1,10 +1,11 @@
 use crate::model::blank_node::BlankNode;
 use crate::model::literal::Literal;
 use crate::model::named_node::NamedNode;
+use crate::model::{BlankNodeRef, LiteralRef, NamedNodeRef};
 use rio_api::model as rio;
 use std::fmt;
 
-/// The union of [IRIs](https://www.w3.org/TR/rdf11-concepts/#dfn-iri) and [blank nodes](https://www.w3.org/TR/rdf11-concepts/#dfn-blank-node).
+/// The owned union of [IRIs](https://www.w3.org/TR/rdf11-concepts/#dfn-iri) and [blank nodes](https://www.w3.org/TR/rdf11-concepts/#dfn-blank-node).
 #[derive(Eq, PartialEq, Debug, Clone, Hash)]
 pub enum NamedOrBlankNode {
     NamedNode(NamedNode),
@@ -13,51 +14,136 @@ pub enum NamedOrBlankNode {
 
 impl NamedOrBlankNode {
     pub fn is_named_node(&self) -> bool {
-        match self {
-            NamedOrBlankNode::NamedNode(_) => true,
-            NamedOrBlankNode::BlankNode(_) => false,
-        }
+        self.as_ref().is_named_node()
     }
 
     pub fn is_blank_node(&self) -> bool {
+        self.as_ref().is_blank_node()
+    }
+
+    pub fn as_ref(&self) -> NamedOrBlankNodeRef<'_> {
         match self {
-            NamedOrBlankNode::NamedNode(_) => false,
-            NamedOrBlankNode::BlankNode(_) => true,
+            Self::NamedNode(node) => NamedOrBlankNodeRef::NamedNode(node.as_ref()),
+            Self::BlankNode(node) => NamedOrBlankNodeRef::BlankNode(node.as_ref()),
         }
     }
 }
 
 impl fmt::Display for NamedOrBlankNode {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        match self {
-            NamedOrBlankNode::NamedNode(node) => node.fmt(f),
-            NamedOrBlankNode::BlankNode(node) => node.fmt(f),
-        }
+        self.as_ref().fmt(f)
     }
 }
 
 impl From<NamedNode> for NamedOrBlankNode {
     fn from(node: NamedNode) -> Self {
-        NamedOrBlankNode::NamedNode(node)
+        Self::NamedNode(node)
+    }
+}
+
+impl From<NamedNodeRef<'_>> for NamedOrBlankNode {
+    fn from(node: NamedNodeRef<'_>) -> Self {
+        node.into_owned().into()
     }
 }
 
 impl From<BlankNode> for NamedOrBlankNode {
     fn from(node: BlankNode) -> Self {
-        NamedOrBlankNode::BlankNode(node)
+        Self::BlankNode(node)
+    }
+}
+
+impl From<BlankNodeRef<'_>> for NamedOrBlankNode {
+    fn from(node: BlankNodeRef<'_>) -> Self {
+        node.into_owned().into()
+    }
+}
+
+/// The borrowed union of [IRIs](https://www.w3.org/TR/rdf11-concepts/#dfn-iri) and [blank nodes](https://www.w3.org/TR/rdf11-concepts/#dfn-blank-node).
+#[derive(Eq, PartialEq, Debug, Clone, Copy, Hash)]
+pub enum NamedOrBlankNodeRef<'a> {
+    NamedNode(NamedNodeRef<'a>),
+    BlankNode(BlankNodeRef<'a>),
+}
+
+impl<'a> NamedOrBlankNodeRef<'a> {
+    pub fn is_named_node(&self) -> bool {
+        match self {
+            Self::NamedNode(_) => true,
+            Self::BlankNode(_) => false,
+        }
+    }
+
+    pub fn is_blank_node(&self) -> bool {
+        match self {
+            Self::NamedNode(_) => false,
+            Self::BlankNode(_) => true,
+        }
+    }
+
+    pub fn into_owned(self) -> NamedOrBlankNode {
+        match self {
+            Self::NamedNode(node) => NamedOrBlankNode::NamedNode(node.into_owned()),
+            Self::BlankNode(node) => NamedOrBlankNode::BlankNode(node.into_owned()),
+        }
     }
 }
 
-impl<'a> From<&'a NamedOrBlankNode> for rio::NamedOrBlankNode<'a> {
+impl fmt::Display for NamedOrBlankNodeRef<'_> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Self::NamedNode(node) => node.fmt(f),
+            Self::BlankNode(node) => node.fmt(f),
+        }
+    }
+}
+
+impl<'a> From<NamedNodeRef<'a>> for NamedOrBlankNodeRef<'a> {
+    fn from(node: NamedNodeRef<'a>) -> Self {
+        Self::NamedNode(node)
+    }
+}
+
+impl<'a> From<&'a NamedNode> for NamedOrBlankNodeRef<'a> {
+    fn from(node: &'a NamedNode) -> Self {
+        node.as_ref().into()
+    }
+}
+
+impl<'a> From<BlankNodeRef<'a>> for NamedOrBlankNodeRef<'a> {
+    fn from(node: BlankNodeRef<'a>) -> Self {
+        Self::BlankNode(node)
+    }
+}
+
+impl<'a> From<&'a BlankNode> for NamedOrBlankNodeRef<'a> {
+    fn from(node: &'a BlankNode) -> Self {
+        node.as_ref().into()
+    }
+}
+
+impl<'a> From<&'a NamedOrBlankNode> for NamedOrBlankNodeRef<'a> {
     fn from(node: &'a NamedOrBlankNode) -> Self {
+        node.as_ref()
+    }
+}
+
+impl<'a> From<NamedOrBlankNodeRef<'a>> for NamedOrBlankNode {
+    fn from(node: NamedOrBlankNodeRef<'a>) -> Self {
+        node.into_owned()
+    }
+}
+
+impl<'a> From<NamedOrBlankNodeRef<'a>> for rio::NamedOrBlankNode<'a> {
+    fn from(node: NamedOrBlankNodeRef<'a>) -> Self {
         match node {
-            NamedOrBlankNode::NamedNode(node) => rio::NamedNode::from(node).into(),
-            NamedOrBlankNode::BlankNode(node) => rio::BlankNode::from(node).into(),
+            NamedOrBlankNodeRef::NamedNode(node) => rio::NamedNode::from(node).into(),
+            NamedOrBlankNodeRef::BlankNode(node) => rio::BlankNode::from(node).into(),
         }
     }
 }
 
-/// An RDF [term](https://www.w3.org/TR/rdf11-concepts/#dfn-rdf-term)
+/// An owned RDF [term](https://www.w3.org/TR/rdf11-concepts/#dfn-rdf-term)
 /// It is the union of [IRIs](https://www.w3.org/TR/rdf11-concepts/#dfn-iri), [blank nodes](https://www.w3.org/TR/rdf11-concepts/#dfn-blank-node) and [literals](https://www.w3.org/TR/rdf11-concepts/#dfn-literal).
 #[derive(Eq, PartialEq, Debug, Clone, Hash)]
 pub enum Term {
@@ -68,75 +154,207 @@ pub enum Term {
 
 impl Term {
     pub fn is_named_node(&self) -> bool {
-        match self {
-            Term::NamedNode(_) => true,
-            _ => false,
-        }
+        self.as_ref().is_named_node()
     }
 
     pub fn is_blank_node(&self) -> bool {
-        match self {
-            Term::BlankNode(_) => true,
-            _ => false,
-        }
+        self.as_ref().is_blank_node()
     }
 
     pub fn is_literal(&self) -> bool {
+        self.as_ref().is_literal()
+    }
+
+    pub fn as_ref(&self) -> TermRef<'_> {
         match self {
-            Term::Literal(_) => true,
-            _ => false,
+            Self::NamedNode(node) => TermRef::NamedNode(node.as_ref()),
+            Self::BlankNode(node) => TermRef::BlankNode(node.as_ref()),
+            Self::Literal(literal) => TermRef::Literal(literal.as_ref()),
         }
     }
 }
 
 impl fmt::Display for Term {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        match self {
-            Term::NamedNode(node) => node.fmt(f),
-            Term::BlankNode(node) => node.fmt(f),
-            Term::Literal(literal) => literal.fmt(f),
-        }
+        self.as_ref().fmt(f)
     }
 }
 
 impl From<NamedNode> for Term {
     fn from(node: NamedNode) -> Self {
-        Term::NamedNode(node)
+        Self::NamedNode(node)
+    }
+}
+
+impl From<NamedNodeRef<'_>> for Term {
+    fn from(node: NamedNodeRef<'_>) -> Self {
+        node.into_owned().into()
     }
 }
 
 impl From<BlankNode> for Term {
     fn from(node: BlankNode) -> Self {
-        Term::BlankNode(node)
+        Self::BlankNode(node)
+    }
+}
+
+impl From<BlankNodeRef<'_>> for Term {
+    fn from(node: BlankNodeRef<'_>) -> Self {
+        node.into_owned().into()
     }
 }
 
 impl From<Literal> for Term {
     fn from(literal: Literal) -> Self {
-        Term::Literal(literal)
+        Self::Literal(literal)
+    }
+}
+
+impl From<LiteralRef<'_>> for Term {
+    fn from(literal: LiteralRef<'_>) -> Self {
+        literal.into_owned().into()
     }
 }
 
 impl From<NamedOrBlankNode> for Term {
-    fn from(resource: NamedOrBlankNode) -> Self {
-        match resource {
+    fn from(node: NamedOrBlankNode) -> Self {
+        match node {
             NamedOrBlankNode::NamedNode(node) => node.into(),
             NamedOrBlankNode::BlankNode(node) => node.into(),
         }
     }
 }
 
-impl<'a> From<&'a Term> for rio::Term<'a> {
+impl From<NamedOrBlankNodeRef<'_>> for Term {
+    fn from(node: NamedOrBlankNodeRef<'_>) -> Self {
+        node.into_owned().into()
+    }
+}
+
+/// A borrowed RDF [term](https://www.w3.org/TR/rdf11-concepts/#dfn-rdf-term)
+/// It is the union of [IRIs](https://www.w3.org/TR/rdf11-concepts/#dfn-iri), [blank nodes](https://www.w3.org/TR/rdf11-concepts/#dfn-blank-node) and [literals](https://www.w3.org/TR/rdf11-concepts/#dfn-literal).
+#[derive(Eq, PartialEq, Debug, Clone, Copy, Hash)]
+pub enum TermRef<'a> {
+    NamedNode(NamedNodeRef<'a>),
+    BlankNode(BlankNodeRef<'a>),
+    Literal(LiteralRef<'a>),
+}
+
+impl<'a> TermRef<'a> {
+    pub fn is_named_node(&self) -> bool {
+        match self {
+            Self::NamedNode(_) => true,
+            _ => false,
+        }
+    }
+
+    pub fn is_blank_node(&self) -> bool {
+        match self {
+            Self::BlankNode(_) => true,
+            _ => false,
+        }
+    }
+
+    pub fn is_literal(&self) -> bool {
+        match self {
+            Self::Literal(_) => true,
+            _ => false,
+        }
+    }
+
+    pub fn into_owned(self) -> Term {
+        match self {
+            Self::NamedNode(node) => Term::NamedNode(node.into_owned()),
+            Self::BlankNode(node) => Term::BlankNode(node.into_owned()),
+            Self::Literal(literal) => Term::Literal(literal.into_owned()),
+        }
+    }
+}
+
+impl fmt::Display for TermRef<'_> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Self::NamedNode(node) => node.fmt(f),
+            Self::BlankNode(node) => node.fmt(f),
+            Self::Literal(node) => node.fmt(f),
+        }
+    }
+}
+
+impl<'a> From<NamedNodeRef<'a>> for TermRef<'a> {
+    fn from(node: NamedNodeRef<'a>) -> Self {
+        Self::NamedNode(node)
+    }
+}
+
+impl<'a> From<&'a NamedNode> for TermRef<'a> {
+    fn from(node: &'a NamedNode) -> Self {
+        node.as_ref().into()
+    }
+}
+
+impl<'a> From<BlankNodeRef<'a>> for TermRef<'a> {
+    fn from(node: BlankNodeRef<'a>) -> Self {
+        Self::BlankNode(node)
+    }
+}
+
+impl<'a> From<&'a BlankNode> for TermRef<'a> {
+    fn from(node: &'a BlankNode) -> Self {
+        node.as_ref().into()
+    }
+}
+
+impl<'a> From<LiteralRef<'a>> for TermRef<'a> {
+    fn from(literal: LiteralRef<'a>) -> Self {
+        Self::Literal(literal)
+    }
+}
+
+impl<'a> From<&'a Literal> for TermRef<'a> {
+    fn from(literal: &'a Literal) -> Self {
+        literal.as_ref().into()
+    }
+}
+
+impl<'a> From<NamedOrBlankNodeRef<'a>> for TermRef<'a> {
+    fn from(node: NamedOrBlankNodeRef<'a>) -> Self {
+        match node {
+            NamedOrBlankNodeRef::NamedNode(node) => node.into(),
+            NamedOrBlankNodeRef::BlankNode(node) => node.into(),
+        }
+    }
+}
+
+impl<'a> From<&'a NamedOrBlankNode> for TermRef<'a> {
+    fn from(node: &'a NamedOrBlankNode) -> Self {
+        node.as_ref().into()
+    }
+}
+
+impl<'a> From<&'a Term> for TermRef<'a> {
     fn from(node: &'a Term) -> Self {
+        node.as_ref()
+    }
+}
+
+impl<'a> From<TermRef<'a>> for Term {
+    fn from(node: TermRef<'a>) -> Self {
+        node.into_owned()
+    }
+}
+
+impl<'a> From<TermRef<'a>> for rio::Term<'a> {
+    fn from(node: TermRef<'a>) -> Self {
         match node {
-            Term::NamedNode(node) => rio::NamedNode::from(node).into(),
-            Term::BlankNode(node) => rio::BlankNode::from(node).into(),
-            Term::Literal(node) => rio::Literal::from(node).into(),
+            TermRef::NamedNode(node) => rio::NamedNode::from(node).into(),
+            TermRef::BlankNode(node) => rio::BlankNode::from(node).into(),
+            TermRef::Literal(node) => rio::Literal::from(node).into(),
         }
     }
 }
 
-/// A [RDF triple](https://www.w3.org/TR/rdf11-concepts/#dfn-rdf-triple)
+/// An owned [RDF triple](https://www.w3.org/TR/rdf11-concepts/#dfn-rdf-triple)
 #[derive(Eq, PartialEq, Debug, Clone, Hash)]
 pub struct Triple {
     /// The [subject](https://www.w3.org/TR/rdf11-concepts/#dfn-subject) of this triple
@@ -202,25 +420,97 @@ impl Triple {
             graph_name: graph_name.into(),
         }
     }
+
+    pub fn as_ref(&self) -> TripleRef<'_> {
+        TripleRef {
+            subject: self.subject.as_ref(),
+            predicate: self.predicate.as_ref(),
+            object: self.object.as_ref(),
+        }
+    }
 }
 
 impl fmt::Display for Triple {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        rio::Triple::from(self).fmt(f)
+        self.as_ref().fmt(f)
+    }
+}
+
+/// A borrowed [RDF triple](https://www.w3.org/TR/rdf11-concepts/#dfn-rdf-triple)
+#[derive(Eq, PartialEq, Debug, Clone, Copy, Hash)]
+pub struct TripleRef<'a> {
+    /// The [subject](https://www.w3.org/TR/rdf11-concepts/#dfn-subject) of this triple
+    pub subject: NamedOrBlankNodeRef<'a>,
+
+    /// The [predicate](https://www.w3.org/TR/rdf11-concepts/#dfn-predicate) of this triple
+    pub predicate: NamedNodeRef<'a>,
+
+    /// The [object](https://www.w3.org/TR/rdf11-concepts/#dfn-object) of this triple
+    pub object: TermRef<'a>,
+}
+
+impl<'a> TripleRef<'a> {
+    /// Builds an RDF [triple](https://www.w3.org/TR/rdf11-concepts/#dfn-rdf-triple)
+    pub fn new(
+        subject: impl Into<NamedOrBlankNodeRef<'a>>,
+        predicate: impl Into<NamedNodeRef<'a>>,
+        object: impl Into<TermRef<'a>>,
+    ) -> Self {
+        Self {
+            subject: subject.into(),
+            predicate: predicate.into(),
+            object: object.into(),
+        }
+    }
+
+    /// Encodes that this triple is in a [RDF dataset](https://www.w3.org/TR/rdf11-concepts/#dfn-rdf-dataset)
+    pub fn in_graph(self, graph_name: impl Into<GraphNameRef<'a>>) -> QuadRef<'a> {
+        QuadRef {
+            subject: self.subject,
+            predicate: self.predicate,
+            object: self.object,
+            graph_name: graph_name.into(),
+        }
+    }
+
+    pub fn into_owned(self) -> Triple {
+        Triple {
+            subject: self.subject.into_owned(),
+            predicate: self.predicate.into_owned(),
+            object: self.object.into_owned(),
+        }
+    }
+}
+
+impl fmt::Display for TripleRef<'_> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        rio::Triple::from(*self).fmt(f)
+    }
+}
+
+impl<'a> From<&'a Triple> for TripleRef<'a> {
+    fn from(triple: &'a Triple) -> Self {
+        triple.as_ref()
     }
 }
 
-impl<'a> From<&'a Triple> for rio::Triple<'a> {
-    fn from(node: &'a Triple) -> Self {
+impl<'a> From<TripleRef<'a>> for Triple {
+    fn from(triple: TripleRef<'a>) -> Self {
+        triple.into_owned()
+    }
+}
+
+impl<'a> From<TripleRef<'a>> for rio::Triple<'a> {
+    fn from(triple: TripleRef<'a>) -> Self {
         rio::Triple {
-            subject: (&node.subject).into(),
-            predicate: (&node.predicate).into(),
-            object: (&node.object).into(),
+            subject: triple.subject.into(),
+            predicate: triple.predicate.into(),
+            object: triple.object.into(),
         }
     }
 }
 
-/// A possible graph name.
+/// A possible owned graph name.
 /// It is the union of [IRIs](https://www.w3.org/TR/rdf11-concepts/#dfn-iri), [blank nodes](https://www.w3.org/TR/rdf11-concepts/#dfn-blank-node) and the [default graph name](https://www.w3.org/TR/rdf11-concepts/#dfn-default-graph).
 #[derive(Eq, PartialEq, Debug, Clone, Hash)]
 pub enum GraphName {
@@ -231,34 +521,29 @@ pub enum GraphName {
 
 impl GraphName {
     pub fn is_named_node(&self) -> bool {
-        match self {
-            GraphName::NamedNode(_) => true,
-            _ => false,
-        }
+        self.as_ref().is_named_node()
     }
 
     pub fn is_blank_node(&self) -> bool {
-        match self {
-            GraphName::BlankNode(_) => true,
-            _ => false,
-        }
+        self.as_ref().is_blank_node()
     }
 
     pub fn is_default_graph(&self) -> bool {
+        self.as_ref().is_default_graph()
+    }
+
+    pub fn as_ref(&self) -> GraphNameRef<'_> {
         match self {
-            GraphName::DefaultGraph => true,
-            _ => false,
+            Self::NamedNode(node) => GraphNameRef::NamedNode(node.as_ref()),
+            Self::BlankNode(node) => GraphNameRef::BlankNode(node.as_ref()),
+            Self::DefaultGraph => GraphNameRef::DefaultGraph,
         }
     }
 }
 
 impl fmt::Display for GraphName {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        match self {
-            GraphName::NamedNode(node) => node.fmt(f),
-            GraphName::BlankNode(node) => node.fmt(f),
-            GraphName::DefaultGraph => write!(f, "DEFAULT"),
-        }
+        self.as_ref().fmt(f)
     }
 }
 
@@ -268,12 +553,24 @@ impl From<NamedNode> for GraphName {
     }
 }
 
+impl From<NamedNodeRef<'_>> for GraphName {
+    fn from(node: NamedNodeRef<'_>) -> Self {
+        node.into_owned().into()
+    }
+}
+
 impl From<BlankNode> for GraphName {
     fn from(node: BlankNode) -> Self {
         GraphName::BlankNode(node)
     }
 }
 
+impl From<BlankNodeRef<'_>> for GraphName {
+    fn from(node: BlankNodeRef<'_>) -> Self {
+        node.into_owned().into()
+    }
+}
+
 impl From<NamedOrBlankNode> for GraphName {
     fn from(node: NamedOrBlankNode) -> Self {
         match node {
@@ -283,6 +580,12 @@ impl From<NamedOrBlankNode> for GraphName {
     }
 }
 
+impl From<NamedOrBlankNodeRef<'_>> for GraphName {
+    fn from(node: NamedOrBlankNodeRef<'_>) -> Self {
+        node.into_owned().into()
+    }
+}
+
 impl From<Option<NamedOrBlankNode>> for GraphName {
     fn from(name: Option<NamedOrBlankNode>) -> Self {
         if let Some(node) = name {
@@ -303,17 +606,138 @@ impl From<GraphName> for Option<NamedOrBlankNode> {
     }
 }
 
-impl<'a> From<&'a GraphName> for Option<rio::NamedOrBlankNode<'a>> {
-    fn from(name: &'a GraphName) -> Self {
+/// A possible borrowed graph name.
+/// It is the union of [IRIs](https://www.w3.org/TR/rdf11-concepts/#dfn-iri), [blank nodes](https://www.w3.org/TR/rdf11-concepts/#dfn-blank-node) and the [default graph name](https://www.w3.org/TR/rdf11-concepts/#dfn-default-graph).
+#[derive(Eq, PartialEq, Debug, Clone, Copy, Hash)]
+pub enum GraphNameRef<'a> {
+    NamedNode(NamedNodeRef<'a>),
+    BlankNode(BlankNodeRef<'a>),
+    DefaultGraph,
+}
+
+impl<'a> GraphNameRef<'a> {
+    pub fn is_named_node(&self) -> bool {
+        match self {
+            GraphNameRef::NamedNode(_) => true,
+            _ => false,
+        }
+    }
+
+    pub fn is_blank_node(&self) -> bool {
+        match self {
+            GraphNameRef::BlankNode(_) => true,
+            _ => false,
+        }
+    }
+
+    pub fn is_default_graph(&self) -> bool {
+        match self {
+            GraphNameRef::DefaultGraph => true,
+            _ => false,
+        }
+    }
+
+    pub fn into_owned(self) -> GraphName {
+        match self {
+            Self::NamedNode(node) => GraphName::NamedNode(node.into_owned()),
+            Self::BlankNode(node) => GraphName::BlankNode(node.into_owned()),
+            Self::DefaultGraph => GraphName::DefaultGraph,
+        }
+    }
+}
+
+impl fmt::Display for GraphNameRef<'_> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Self::NamedNode(node) => node.fmt(f),
+            Self::BlankNode(node) => node.fmt(f),
+            Self::DefaultGraph => write!(f, "DEFAULT"),
+        }
+    }
+}
+
+impl<'a> From<NamedNodeRef<'a>> for GraphNameRef<'a> {
+    fn from(node: NamedNodeRef<'a>) -> Self {
+        Self::NamedNode(node)
+    }
+}
+
+impl<'a> From<&'a NamedNode> for GraphNameRef<'a> {
+    fn from(node: &'a NamedNode) -> Self {
+        node.as_ref().into()
+    }
+}
+
+impl<'a> From<BlankNodeRef<'a>> for GraphNameRef<'a> {
+    fn from(node: BlankNodeRef<'a>) -> Self {
+        Self::BlankNode(node)
+    }
+}
+
+impl<'a> From<&'a BlankNode> for GraphNameRef<'a> {
+    fn from(node: &'a BlankNode) -> Self {
+        node.as_ref().into()
+    }
+}
+
+impl<'a> From<NamedOrBlankNodeRef<'a>> for GraphNameRef<'a> {
+    fn from(node: NamedOrBlankNodeRef<'a>) -> Self {
+        match node {
+            NamedOrBlankNodeRef::NamedNode(node) => node.into(),
+            NamedOrBlankNodeRef::BlankNode(node) => node.into(),
+        }
+    }
+}
+
+impl<'a> From<&'a NamedOrBlankNode> for GraphNameRef<'a> {
+    fn from(node: &'a NamedOrBlankNode) -> Self {
+        node.as_ref().into()
+    }
+}
+
+impl<'a> From<&'a GraphName> for GraphNameRef<'a> {
+    fn from(node: &'a GraphName) -> Self {
+        node.as_ref()
+    }
+}
+
+impl<'a> From<GraphNameRef<'a>> for GraphName {
+    fn from(node: GraphNameRef<'a>) -> Self {
+        node.into_owned()
+    }
+}
+
+impl<'a> From<Option<NamedOrBlankNodeRef<'a>>> for GraphNameRef<'a> {
+    fn from(name: Option<NamedOrBlankNodeRef<'a>>) -> Self {
+        if let Some(node) = name {
+            node.into()
+        } else {
+            GraphNameRef::DefaultGraph
+        }
+    }
+}
+
+impl<'a> From<GraphNameRef<'a>> for Option<NamedOrBlankNodeRef<'a>> {
+    fn from(name: GraphNameRef<'a>) -> Self {
         match name {
-            GraphName::NamedNode(node) => Some(rio::NamedNode::from(node).into()),
-            GraphName::BlankNode(node) => Some(rio::BlankNode::from(node).into()),
-            GraphName::DefaultGraph => None,
+            GraphNameRef::NamedNode(node) => Some(node.into()),
+            GraphNameRef::BlankNode(node) => Some(node.into()),
+            GraphNameRef::DefaultGraph => None,
+        }
+    }
+}
+
+impl<'a> From<GraphNameRef<'a>> for Option<rio::NamedOrBlankNode<'a>> {
+    fn from(name: GraphNameRef<'a>) -> Self {
+        match name {
+            GraphNameRef::NamedNode(node) => Some(rio::NamedNode::from(node).into()),
+            GraphNameRef::BlankNode(node) => Some(rio::BlankNode::from(node).into()),
+            GraphNameRef::DefaultGraph => None,
         }
     }
 }
 
-/// A [triple](https://www.w3.org/TR/rdf11-concepts/#dfn-rdf-triple) in a [RDF dataset](https://www.w3.org/TR/rdf11-concepts/#dfn-rdf-dataset)
+/// An owned [triple](https://www.w3.org/TR/rdf11-concepts/#dfn-rdf-triple) in a [RDF dataset](https://www.w3.org/TR/rdf11-concepts/#dfn-rdf-dataset)
 #[derive(Eq, PartialEq, Debug, Clone, Hash)]
 pub struct Quad {
     /// The [subject](https://www.w3.org/TR/rdf11-concepts/#dfn-subject) of this triple
@@ -394,27 +818,83 @@ impl Quad {
     pub fn destruct(self) -> (NamedOrBlankNode, NamedNode, Term, GraphName) {
         (self.subject, self.predicate, self.object, self.graph_name)
     }
+
+    pub fn as_ref(&self) -> QuadRef<'_> {
+        QuadRef {
+            subject: self.subject.as_ref(),
+            predicate: self.predicate.as_ref(),
+            object: self.object.as_ref(),
+            graph_name: self.graph_name.as_ref(),
+        }
+    }
 }
 
 impl fmt::Display for Quad {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        rio::Quad::from(self).fmt(f)
+        self.as_ref().fmt(f)
     }
 }
 
-impl<'a> From<&'a Quad> for rio::Quad<'a> {
-    fn from(node: &'a Quad) -> Self {
-        rio::Quad {
-            subject: (&node.subject).into(),
-            predicate: (&node.predicate).into(),
-            object: (&node.object).into(),
-            graph_name: (&node.graph_name).into(),
+impl From<Quad> for Triple {
+    fn from(quad: Quad) -> Self {
+        Self {
+            subject: quad.subject,
+            predicate: quad.predicate,
+            object: quad.object,
         }
     }
 }
 
-impl From<Quad> for Triple {
-    fn from(quad: Quad) -> Self {
+/// A borrowed [triple](https://www.w3.org/TR/rdf11-concepts/#dfn-rdf-triple) in a [RDF dataset](https://www.w3.org/TR/rdf11-concepts/#dfn-rdf-dataset)
+#[derive(Eq, PartialEq, Debug, Clone, Copy, Hash)]
+pub struct QuadRef<'a> {
+    /// The [subject](https://www.w3.org/TR/rdf11-concepts/#dfn-subject) of this triple
+    pub subject: NamedOrBlankNodeRef<'a>,
+
+    /// The [predicate](https://www.w3.org/TR/rdf11-concepts/#dfn-predicate) of this triple
+    pub predicate: NamedNodeRef<'a>,
+
+    /// The [object](https://www.w3.org/TR/rdf11-concepts/#dfn-object) of this triple
+    pub object: TermRef<'a>,
+
+    /// The name of the RDF [graph](https://www.w3.org/TR/rdf11-concepts/#dfn-rdf-graph) in which the triple is.
+    pub graph_name: GraphNameRef<'a>,
+}
+
+impl<'a> QuadRef<'a> {
+    /// Builds an RDF [triple](https://www.w3.org/TR/rdf11-concepts/#dfn-rdf-triple) in a [RDF dataset](https://www.w3.org/TR/rdf11-concepts/#dfn-rdf-dataset)
+    pub fn new(
+        subject: impl Into<NamedOrBlankNodeRef<'a>>,
+        predicate: impl Into<NamedNodeRef<'a>>,
+        object: impl Into<TermRef<'a>>,
+        graph_name: impl Into<GraphNameRef<'a>>,
+    ) -> Self {
+        Self {
+            subject: subject.into(),
+            predicate: predicate.into(),
+            object: object.into(),
+            graph_name: graph_name.into(),
+        }
+    }
+
+    pub fn into_owned(self) -> Quad {
+        Quad {
+            subject: self.subject.into_owned(),
+            predicate: self.predicate.into_owned(),
+            object: self.object.into_owned(),
+            graph_name: self.graph_name.into_owned(),
+        }
+    }
+}
+
+impl fmt::Display for QuadRef<'_> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        rio::Quad::from(*self).fmt(f)
+    }
+}
+
+impl<'a> From<QuadRef<'a>> for TripleRef<'a> {
+    fn from(quad: QuadRef<'a>) -> Self {
         Self {
             subject: quad.subject,
             predicate: quad.predicate,
@@ -422,3 +902,26 @@ impl From<Quad> for Triple {
         }
     }
 }
+
+impl<'a> From<&'a Quad> for QuadRef<'a> {
+    fn from(quad: &'a Quad) -> Self {
+        quad.as_ref()
+    }
+}
+
+impl<'a> From<QuadRef<'a>> for Quad {
+    fn from(quad: QuadRef<'a>) -> Self {
+        quad.into_owned()
+    }
+}
+
+impl<'a> From<QuadRef<'a>> for rio::Quad<'a> {
+    fn from(quad: QuadRef<'a>) -> Self {
+        rio::Quad {
+            subject: quad.subject.into(),
+            predicate: quad.predicate.into(),
+            object: quad.object.into(),
+            graph_name: quad.graph_name.into(),
+        }
+    }
+}
diff --git a/lib/src/model/vocab.rs b/lib/src/model/vocab.rs
index 022cddc5..f1f9e0c0 100644
--- a/lib/src/model/vocab.rs
+++ b/lib/src/model/vocab.rs
@@ -2,212 +2,204 @@
 
 pub mod rdf {
     //! [RDF 1.1](https://www.w3.org/TR/rdf11-concepts/) vocabulary
-    use crate::model::named_node::NamedNode;
-    use lazy_static::lazy_static;
+    use crate::model::named_node::NamedNodeRef;
 
-    lazy_static! {
-        /// The class of containers of alternatives.
-        pub static ref ALT: NamedNode =
-            NamedNode::new_unchecked("http://www.w3.org/1999/02/22-rdf-syntax-ns#Alt");
-        /// The class of unordered containers.
-        pub static ref BAG: NamedNode =
-            NamedNode::new_unchecked("http://www.w3.org/1999/02/22-rdf-syntax-ns#Bag");
-        /// The first item in the subject RDF list.
-        pub static ref FIRST: NamedNode =
-            NamedNode::new_unchecked("http://www.w3.org/1999/02/22-rdf-syntax-ns#first");
-        /// The class of HTML literal values.
-        pub static ref HTML: NamedNode =
-            NamedNode::new_unchecked("http://www.w3.org/1999/02/22-rdf-syntax-ns#HTML");
-        /// The class of language-tagged string literal values.
-        pub static ref LANG_STRING: NamedNode =
-            NamedNode::new_unchecked("http://www.w3.org/1999/02/22-rdf-syntax-ns#langString");
-        /// The class of RDF Lists.
-        pub static ref LIST: NamedNode =
-            NamedNode::new_unchecked("http://www.w3.org/1999/02/22-rdf-syntax-ns#List");
-        pub static ref NIL: NamedNode =
-            NamedNode::new_unchecked("http://www.w3.org/1999/02/22-rdf-syntax-ns#nil");
-        /// The object of the subject RDF statement.
-        pub static ref OBJECT: NamedNode =
-            NamedNode::new_unchecked("http://www.w3.org/1999/02/22-rdf-syntax-ns#object");
-        /// The predicate of the subject RDF statement.
-        pub static ref PREDICATE: NamedNode =
-            NamedNode::new_unchecked("http://www.w3.org/1999/02/22-rdf-syntax-ns#predicate");
-        /// The class of RDF properties.
-        pub static ref PROPERTY: NamedNode =
-            NamedNode::new_unchecked("http://www.w3.org/1999/02/22-rdf-syntax-ns#Property");
-        /// The rest of the subject RDF list after the first item.
-        pub static ref REST: NamedNode =
-            NamedNode::new_unchecked("http://www.w3.org/1999/02/22-rdf-syntax-ns#rest");
-        /// The class of ordered containers.
-        pub static ref SEQ: NamedNode =
-            NamedNode::new_unchecked("http://www.w3.org/1999/02/22-rdf-syntax-ns#Seq");
-        /// The class of RDF statements.
-        pub static ref STATEMENT: NamedNode =
-            NamedNode::new_unchecked("http://www.w3.org/1999/02/22-rdf-syntax-ns#Statement");
-        /// The subject of the subject RDF statement.
-        pub static ref SUBJECT: NamedNode =
-            NamedNode::new_unchecked("http://www.w3.org/1999/02/22-rdf-syntax-ns#subject");
-        /// The subject is an instance of a class.
-        pub static ref TYPE: NamedNode =
-            NamedNode::new_unchecked("http://www.w3.org/1999/02/22-rdf-syntax-ns#type");
-        /// Idiomatic property used for structured values.
-        pub static ref VALUE: NamedNode =
-            NamedNode::new_unchecked("http://www.w3.org/1999/02/22-rdf-syntax-ns#value");
-        /// The class of XML literal values.
-        pub static ref XML_LITERAL: NamedNode =
-            NamedNode::new_unchecked("http://www.w3.org/1999/02/22-rdf-syntax-ns#XMLLiteral");
-    }
+    /// The class of containers of alternatives.
+    pub const ALT: NamedNodeRef<'_> =
+        NamedNodeRef::new_unchecked("http://www.w3.org/1999/02/22-rdf-syntax-ns#Alt");
+    /// The class of unordered containers.
+    pub const BAG: NamedNodeRef<'_> =
+        NamedNodeRef::new_unchecked("http://www.w3.org/1999/02/22-rdf-syntax-ns#Bag");
+    /// The first item in the subject RDF list.
+    pub const FIRST: NamedNodeRef<'_> =
+        NamedNodeRef::new_unchecked("http://www.w3.org/1999/02/22-rdf-syntax-ns#first");
+    /// The class of HTML literal values.
+    pub const HTML: NamedNodeRef<'_> =
+        NamedNodeRef::new_unchecked("http://www.w3.org/1999/02/22-rdf-syntax-ns#HTML");
+    /// The class of language-tagged string literal values.
+    pub const LANG_STRING: NamedNodeRef<'_> =
+        NamedNodeRef::new_unchecked("http://www.w3.org/1999/02/22-rdf-syntax-ns#langString");
+    /// The class of RDF Lists.
+    pub const LIST: NamedNodeRef<'_> =
+        NamedNodeRef::new_unchecked("http://www.w3.org/1999/02/22-rdf-syntax-ns#List");
+    pub const NIL: NamedNodeRef<'_> =
+        NamedNodeRef::new_unchecked("http://www.w3.org/1999/02/22-rdf-syntax-ns#nil");
+    /// The object of the subject RDF statement.
+    pub const OBJECT: NamedNodeRef<'_> =
+        NamedNodeRef::new_unchecked("http://www.w3.org/1999/02/22-rdf-syntax-ns#object");
+    /// The predicate of the subject RDF statement.
+    pub const PREDICATE: NamedNodeRef<'_> =
+        NamedNodeRef::new_unchecked("http://www.w3.org/1999/02/22-rdf-syntax-ns#predicate");
+    /// The class of RDF properties.
+    pub const PROPERTY: NamedNodeRef<'_> =
+        NamedNodeRef::new_unchecked("http://www.w3.org/1999/02/22-rdf-syntax-ns#Property");
+    /// The rest of the subject RDF list after the first item.
+    pub const REST: NamedNodeRef<'_> =
+        NamedNodeRef::new_unchecked("http://www.w3.org/1999/02/22-rdf-syntax-ns#rest");
+    /// The class of ordered containers.
+    pub const SEQ: NamedNodeRef<'_> =
+        NamedNodeRef::new_unchecked("http://www.w3.org/1999/02/22-rdf-syntax-ns#Seq");
+    /// The class of RDF statements.
+    pub const STATEMENT: NamedNodeRef<'_> =
+        NamedNodeRef::new_unchecked("http://www.w3.org/1999/02/22-rdf-syntax-ns#Statement");
+    /// The subject of the subject RDF statement.
+    pub const SUBJECT: NamedNodeRef<'_> =
+        NamedNodeRef::new_unchecked("http://www.w3.org/1999/02/22-rdf-syntax-ns#subject");
+    /// The subject is an instance of a class.
+    pub const TYPE: NamedNodeRef<'_> =
+        NamedNodeRef::new_unchecked("http://www.w3.org/1999/02/22-rdf-syntax-ns#type");
+    /// Idiomatic property used for structured values.
+    pub const VALUE: NamedNodeRef<'_> =
+        NamedNodeRef::new_unchecked("http://www.w3.org/1999/02/22-rdf-syntax-ns#value");
+    /// The class of XML literal values.
+    pub const XML_LITERAL: NamedNodeRef<'_> =
+        NamedNodeRef::new_unchecked("http://www.w3.org/1999/02/22-rdf-syntax-ns#XMLLiteral");
 }
 
 pub mod rdfs {
     //! [RDFS](https://www.w3.org/TR/rdf-schema/) vocabulary
-    use crate::model::named_node::NamedNode;
-    use lazy_static::lazy_static;
+    use crate::model::named_node::NamedNodeRef;
 
-    lazy_static! {
-        /// The class of classes.
-        pub static ref CLASS: NamedNode =
-            NamedNode::new_unchecked("http://www.w3.org/2000/01/rdf-schema#Class");
-        /// A description of the subject resource.
-        pub static ref COMMENT: NamedNode =
-            NamedNode::new_unchecked("http://www.w3.org/2000/01/rdf-schema#comment");
-        /// The class of RDF containers.
-        pub static ref CONTAINER: NamedNode =
-            NamedNode::new_unchecked("http://www.w3.org/2000/01/rdf-schema#Container");
-        /// The class of container membership properties, rdf:_1, rdf:_2, ..., all of which are sub-properties of 'member'.
-        pub static ref CONTAINER_MEMBERSHIP_PROPERTY: NamedNode =
-            NamedNode::new_unchecked("http://www.w3.org/2000/01/rdf-schema#ContainerMembershipProperty");
-        /// The class of RDF datatypes.
-        pub static ref DATATYPE: NamedNode =
-            NamedNode::new_unchecked("http://www.w3.org/2000/01/rdf-schema#Datatype");
-        /// A domain of the subject property.
-        pub static ref DOMAIN: NamedNode =
-            NamedNode::new_unchecked("http://www.w3.org/2000/01/rdf-schema#domain");
-        /// The definition of the subject resource.
-        pub static ref IS_DEFINED_BY: NamedNode =
-            NamedNode::new_unchecked("http://www.w3.org/2000/01/rdf-schema#isDefinedBy");
-        /// A human-readable name for the subject.
-        pub static ref LABEL: NamedNode =
-            NamedNode::new_unchecked("http://www.w3.org/2000/01/rdf-schema#label");
-        /// The class of literal values, e.g. textual strings and integers.
-        pub static ref LITERAL: NamedNode =
-            NamedNode::new_unchecked("http://www.w3.org/2000/01/rdf-schema#Literal");
-        /// A member of the subject resource.
-        pub static ref MEMBER: NamedNode =
-            NamedNode::new_unchecked("http://www.w3.org/2000/01/rdf-schema#member");
-        /// A range of the subject property.
-        pub static ref RANGE: NamedNode =
-            NamedNode::new_unchecked("http://www.w3.org/2000/01/rdf-schema#range");
-        /// The class resource, everything.
-        pub static ref RESOURCE: NamedNode =
-            NamedNode::new_unchecked("http://www.w3.org/2000/01/rdf-schema#Resource");
-        /// Further information about the subject resource.
-        pub static ref SEE_ALSO: NamedNode =
-            NamedNode::new_unchecked("http://www.w3.org/2000/01/rdf-schema#seeAlso");
-        /// The subject is a subclass of a class.
-        pub static ref SUB_CLASS_OF: NamedNode =
-            NamedNode::new_unchecked("http://www.w3.org/2000/01/rdf-schema#subClassOf");
-        /// The subject is a subproperty of a property.
-        pub static ref SUB_PROPERTY_OF: NamedNode =
-            NamedNode::new_unchecked("http://www.w3.org/2000/01/rdf-schema#subPropertyOf");
-    }
+    /// The class of classes.
+    pub const CLASS: NamedNodeRef<'_> =
+        NamedNodeRef::new_unchecked("http://www.w3.org/2000/01/rdf-schema#Class");
+    /// A description of the subject resource.
+    pub const COMMENT: NamedNodeRef<'_> =
+        NamedNodeRef::new_unchecked("http://www.w3.org/2000/01/rdf-schema#comment");
+    /// The class of RDF containers.
+    pub const CONTAINER: NamedNodeRef<'_> =
+        NamedNodeRef::new_unchecked("http://www.w3.org/2000/01/rdf-schema#Container");
+    /// The class of container membership properties, rdf:_1, rdf:_2, ..., all of which are sub-properties of 'member'.
+    pub const CONTAINER_MEMBERSHIP_PROPERTY: NamedNodeRef<'_> = NamedNodeRef::new_unchecked(
+        "http://www.w3.org/2000/01/rdf-schema#ContainerMembershipProperty",
+    );
+    /// The class of RDF datatypes.
+    pub const DATATYPE: NamedNodeRef<'_> =
+        NamedNodeRef::new_unchecked("http://www.w3.org/2000/01/rdf-schema#Datatype");
+    /// A domain of the subject property.
+    pub const DOMAIN: NamedNodeRef<'_> =
+        NamedNodeRef::new_unchecked("http://www.w3.org/2000/01/rdf-schema#domain");
+    /// The definition of the subject resource.
+    pub const IS_DEFINED_BY: NamedNodeRef<'_> =
+        NamedNodeRef::new_unchecked("http://www.w3.org/2000/01/rdf-schema#isDefinedBy");
+    /// A human-readable name for the subject.
+    pub const LABEL: NamedNodeRef<'_> =
+        NamedNodeRef::new_unchecked("http://www.w3.org/2000/01/rdf-schema#label");
+    /// The class of literal values, e.g. textual strings and integers.
+    pub const LITERAL: NamedNodeRef<'_> =
+        NamedNodeRef::new_unchecked("http://www.w3.org/2000/01/rdf-schema#Literal");
+    /// A member of the subject resource.
+    pub const MEMBER: NamedNodeRef<'_> =
+        NamedNodeRef::new_unchecked("http://www.w3.org/2000/01/rdf-schema#member");
+    /// A range of the subject property.
+    pub const RANGE: NamedNodeRef<'_> =
+        NamedNodeRef::new_unchecked("http://www.w3.org/2000/01/rdf-schema#range");
+    /// The class resource, everything.
+    pub const RESOURCE: NamedNodeRef<'_> =
+        NamedNodeRef::new_unchecked("http://www.w3.org/2000/01/rdf-schema#Resource");
+    /// Further information about the subject resource.
+    pub const SEE_ALSO: NamedNodeRef<'_> =
+        NamedNodeRef::new_unchecked("http://www.w3.org/2000/01/rdf-schema#seeAlso");
+    /// The subject is a subclass of a class.
+    pub const SUB_CLASS_OF: NamedNodeRef<'_> =
+        NamedNodeRef::new_unchecked("http://www.w3.org/2000/01/rdf-schema#subClassOf");
+    /// The subject is a subproperty of a property.
+    pub const SUB_PROPERTY_OF: NamedNodeRef<'_> =
+        NamedNodeRef::new_unchecked("http://www.w3.org/2000/01/rdf-schema#subPropertyOf");
 }
 
 pub mod xsd {
     //! `NamedNode`s for [RDF compatible XSD datatypes](https://www.w3.org/TR/rdf11-concepts/#dfn-rdf-compatible-xsd-types)
-    use crate::model::named_node::NamedNode;
-    use lazy_static::lazy_static;
+    use crate::model::named_node::NamedNodeRef;
 
-    lazy_static! {
-        /// true, false
-        pub static ref BOOLEAN: NamedNode =
-            NamedNode::new_unchecked("http://www.w3.org/2001/XMLSchema#boolean");
-        /// 128…+127 (8 bit)
-        pub static ref BYTE: NamedNode =
-            NamedNode::new_unchecked("http://www.w3.org/2001/XMLSchema#byte");
-        /// Dates (yyyy-mm-dd) with or without timezone
-        pub static ref DATE: NamedNode =
-            NamedNode::new_unchecked("http://www.w3.org/2001/XMLSchema#date");
-        /// Duration of time (days, hours, minutes, seconds only)
-        pub static ref DAY_TIME_DURATION: NamedNode =
-            NamedNode::new_unchecked("http://www.w3.org/2001/XMLSchema#dayTimeDuration");
-        /// Date and time with or without timezone
-        pub static ref DATE_TIME: NamedNode =
-            NamedNode::new_unchecked("http://www.w3.org/2001/XMLSchema#dateTime");
-        /// Date and time with required timezone
-        pub static ref DATE_TIME_STAMP: NamedNode =
-            NamedNode::new_unchecked("http://www.w3.org/2001/XMLSchema#dateTimeStamp");
-        /// Arbitrary-precision decimal numbers
-        pub static ref DECIMAL: NamedNode =
-            NamedNode::new_unchecked("http://www.w3.org/2001/XMLSchema#decimal");
-        /// 64-bit floating point numbers incl. ±Inf, ±0, NaN
-        pub static ref DOUBLE: NamedNode =
-            NamedNode::new_unchecked("http://www.w3.org/2001/XMLSchema#double");
-        /// Duration of time
-        pub static ref DURATION: NamedNode =
-            NamedNode::new_unchecked("http://www.w3.org/2001/XMLSchema#duration");
-        /// 32-bit floating point numbers incl. ±Inf, ±0, NaN
-        pub static ref FLOAT: NamedNode =
-            NamedNode::new_unchecked("http://www.w3.org/2001/XMLSchema#float");
-        /// Gregorian calendar day of the month
-        pub static ref G_DAY: NamedNode =
-            NamedNode::new_unchecked("http://www.w3.org/2001/XMLSchema#gDay");
-        /// Gregorian calendar month
-        pub static ref G_MONTH: NamedNode =
-            NamedNode::new_unchecked("http://www.w3.org/2001/XMLSchema#gMonth");
-        /// Gregorian calendar month and day
-        pub static ref G_MONTH_DAY: NamedNode =
-            NamedNode::new_unchecked("http://www.w3.org/2001/XMLSchema#gMonthDay");
-        /// Gregorian calendar year
-        pub static ref G_YEAR: NamedNode =
-            NamedNode::new_unchecked("http://www.w3.org/2001/XMLSchema#gYear");
-        /// Gregorian calendar year and month
-        pub static ref G_YEAR_MONTH: NamedNode =
-            NamedNode::new_unchecked("http://www.w3.org/2001/XMLSchema#gYearMonth");
-        /// -2147483648…+2147483647 (32 bit)
-        pub static ref INT: NamedNode =
-            NamedNode::new_unchecked("http://www.w3.org/2001/XMLSchema#int");
-        /// Arbitrary-size integer numbers
-        pub static ref INTEGER: NamedNode =
-            NamedNode::new_unchecked("http://www.w3.org/2001/XMLSchema#integer");
-        /// -9223372036854775808…+9223372036854775807 (64 bit)
-        pub static ref LONG: NamedNode =
-            NamedNode::new_unchecked("http://www.w3.org/2001/XMLSchema#long");
-        /// Integer numbers <0
-        pub static ref NEGATIVE_INTEGER: NamedNode =
-            NamedNode::new_unchecked("http://www.w3.org/2001/XMLSchema#negativeInteger");
-        /// Integer numbers ≥0
-        pub static ref NON_NEGATIVE_INTEGER: NamedNode =
-            NamedNode::new_unchecked("http://www.w3.org/2001/XMLSchema#nonNegativeInteger");
-        /// Integer numbers ≤0
-        pub static ref NON_POSITIVE_INTEGER: NamedNode =
-            NamedNode::new_unchecked("http://www.w3.org/2001/XMLSchema#nonPositiveInteger");
-        /// Integer numbers >0
-        pub static ref POSITIVE_INTEGER: NamedNode =
-            NamedNode::new_unchecked("http://www.w3.org/2001/XMLSchema#positiveInteger");
-        /// Times (hh:mm:ss.sss…) with or without timezone
-        pub static ref TIME: NamedNode =
-            NamedNode::new_unchecked("http://www.w3.org/2001/XMLSchema#time");
-        /// -32768…+32767 (16 bit)
-        pub static ref SHORT: NamedNode =
-            NamedNode::new_unchecked("http://www.w3.org/2001/XMLSchema#short");
-        /// Character strings (but not all Unicode character strings)
-        pub static ref STRING: NamedNode =
-            NamedNode::new_unchecked("http://www.w3.org/2001/XMLSchema#string");
-        /// 0…255 (8 bit)
-        pub static ref UNSIGNED_BYTE: NamedNode =
-            NamedNode::new_unchecked("http://www.w3.org/2001/XMLSchema#unsignedByte");
-        /// 0…4294967295 (32 bit)
-        pub static ref UNSIGNED_INT: NamedNode =
-            NamedNode::new_unchecked("http://www.w3.org/2001/XMLSchema#unsignedInt");
-        /// 0…18446744073709551615 (64 bit)
-        pub static ref UNSIGNED_LONG: NamedNode =
-            NamedNode::new_unchecked("http://www.w3.org/2001/XMLSchema#unsignedLong");
-        /// 0…65535 (16 bit)
-        pub static ref UNSIGNED_SHORT: NamedNode =
-            NamedNode::new_unchecked("http://www.w3.org/2001/XMLSchema#unsignedShort");
-        /// Duration of time (months and years only)
-        pub static ref YEAR_MONTH_DURATION: NamedNode =
-            NamedNode::new_unchecked("http://www.w3.org/2001/XMLSchema#yearMonthDuration");
-    }
+    /// true, false
+    pub const BOOLEAN: NamedNodeRef<'_> =
+        NamedNodeRef::new_unchecked("http://www.w3.org/2001/XMLSchema#boolean");
+    /// 128…+127 (8 bit)
+    pub const BYTE: NamedNodeRef<'_> =
+        NamedNodeRef::new_unchecked("http://www.w3.org/2001/XMLSchema#byte");
+    /// Dates (yyyy-mm-dd) with or without timezone
+    pub const DATE: NamedNodeRef<'_> =
+        NamedNodeRef::new_unchecked("http://www.w3.org/2001/XMLSchema#date");
+    /// Duration of time (days, hours, minutes, seconds only)
+    pub const DAY_TIME_DURATION: NamedNodeRef<'_> =
+        NamedNodeRef::new_unchecked("http://www.w3.org/2001/XMLSchema#dayTimeDuration");
+    /// Date and time with or without timezone
+    pub const DATE_TIME: NamedNodeRef<'_> =
+        NamedNodeRef::new_unchecked("http://www.w3.org/2001/XMLSchema#dateTime");
+    /// Date and time with required timezone
+    pub const DATE_TIME_STAMP: NamedNodeRef<'_> =
+        NamedNodeRef::new_unchecked("http://www.w3.org/2001/XMLSchema#dateTimeStamp");
+    /// Arbitrary-precision decimal numbers
+    pub const DECIMAL: NamedNodeRef<'_> =
+        NamedNodeRef::new_unchecked("http://www.w3.org/2001/XMLSchema#decimal");
+    /// 64-bit floating point numbers incl. ±Inf, ±0, NaN
+    pub const DOUBLE: NamedNodeRef<'_> =
+        NamedNodeRef::new_unchecked("http://www.w3.org/2001/XMLSchema#double");
+    /// Duration of time
+    pub const DURATION: NamedNodeRef<'_> =
+        NamedNodeRef::new_unchecked("http://www.w3.org/2001/XMLSchema#duration");
+    /// 32-bit floating point numbers incl. ±Inf, ±0, NaN
+    pub const FLOAT: NamedNodeRef<'_> =
+        NamedNodeRef::new_unchecked("http://www.w3.org/2001/XMLSchema#float");
+    /// Gregorian calendar day of the month
+    pub const G_DAY: NamedNodeRef<'_> =
+        NamedNodeRef::new_unchecked("http://www.w3.org/2001/XMLSchema#gDay");
+    /// Gregorian calendar month
+    pub const G_MONTH: NamedNodeRef<'_> =
+        NamedNodeRef::new_unchecked("http://www.w3.org/2001/XMLSchema#gMonth");
+    /// Gregorian calendar month and day
+    pub const G_MONTH_DAY: NamedNodeRef<'_> =
+        NamedNodeRef::new_unchecked("http://www.w3.org/2001/XMLSchema#gMonthDay");
+    /// Gregorian calendar year
+    pub const G_YEAR: NamedNodeRef<'_> =
+        NamedNodeRef::new_unchecked("http://www.w3.org/2001/XMLSchema#gYear");
+    /// Gregorian calendar year and month
+    pub const G_YEAR_MONTH: NamedNodeRef<'_> =
+        NamedNodeRef::new_unchecked("http://www.w3.org/2001/XMLSchema#gYearMonth");
+    /// -2147483648…+2147483647 (32 bit)
+    pub const INT: NamedNodeRef<'_> =
+        NamedNodeRef::new_unchecked("http://www.w3.org/2001/XMLSchema#int");
+    /// Arbitrary-size integer numbers
+    pub const INTEGER: NamedNodeRef<'_> =
+        NamedNodeRef::new_unchecked("http://www.w3.org/2001/XMLSchema#integer");
+    /// -9223372036854775808…+9223372036854775807 (64 bit)
+    pub const LONG: NamedNodeRef<'_> =
+        NamedNodeRef::new_unchecked("http://www.w3.org/2001/XMLSchema#long");
+    /// Integer numbers <0
+    pub const NEGATIVE_INTEGER: NamedNodeRef<'_> =
+        NamedNodeRef::new_unchecked("http://www.w3.org/2001/XMLSchema#negativeInteger");
+    /// Integer numbers ≥0
+    pub const NON_NEGATIVE_INTEGER: NamedNodeRef<'_> =
+        NamedNodeRef::new_unchecked("http://www.w3.org/2001/XMLSchema#nonNegativeInteger");
+    /// Integer numbers ≤0
+    pub const NON_POSITIVE_INTEGER: NamedNodeRef<'_> =
+        NamedNodeRef::new_unchecked("http://www.w3.org/2001/XMLSchema#nonPositiveInteger");
+    /// Integer numbers >0
+    pub const POSITIVE_INTEGER: NamedNodeRef<'_> =
+        NamedNodeRef::new_unchecked("http://www.w3.org/2001/XMLSchema#positiveInteger");
+    /// Times (hh:mm:ss.sss…) with or without timezone
+    pub const TIME: NamedNodeRef<'_> =
+        NamedNodeRef::new_unchecked("http://www.w3.org/2001/XMLSchema#time");
+    /// -32768…+32767 (16 bit)
+    pub const SHORT: NamedNodeRef<'_> =
+        NamedNodeRef::new_unchecked("http://www.w3.org/2001/XMLSchema#short");
+    /// Character strings (but not all Unicode character strings)
+    pub const STRING: NamedNodeRef<'_> =
+        NamedNodeRef::new_unchecked("http://www.w3.org/2001/XMLSchema#string");
+    /// 0…255 (8 bit)
+    pub const UNSIGNED_BYTE: NamedNodeRef<'_> =
+        NamedNodeRef::new_unchecked("http://www.w3.org/2001/XMLSchema#unsignedByte");
+    /// 0…4294967295 (32 bit)
+    pub const UNSIGNED_INT: NamedNodeRef<'_> =
+        NamedNodeRef::new_unchecked("http://www.w3.org/2001/XMLSchema#unsignedInt");
+    /// 0…18446744073709551615 (64 bit)
+    pub const UNSIGNED_LONG: NamedNodeRef<'_> =
+        NamedNodeRef::new_unchecked("http://www.w3.org/2001/XMLSchema#unsignedLong");
+    /// 0…65535 (16 bit)
+    pub const UNSIGNED_SHORT: NamedNodeRef<'_> =
+        NamedNodeRef::new_unchecked("http://www.w3.org/2001/XMLSchema#unsignedShort");
+    /// Duration of time (months and years only)
+    pub const YEAR_MONTH_DURATION: NamedNodeRef<'_> =
+        NamedNodeRef::new_unchecked("http://www.w3.org/2001/XMLSchema#yearMonthDuration");
 }
diff --git a/lib/src/sparql/algebra.rs b/lib/src/sparql/algebra.rs
index e9646426..24dbe605 100644
--- a/lib/src/sparql/algebra.rs
+++ b/lib/src/sparql/algebra.rs
@@ -30,6 +30,12 @@ impl From<NamedNode> for NamedNodeOrVariable {
     }
 }
 
+impl From<NamedNodeRef<'_>> for NamedNodeOrVariable {
+    fn from(node: NamedNodeRef<'_>) -> Self {
+        NamedNodeOrVariable::NamedNode(node.into())
+    }
+}
+
 impl From<Variable> for NamedNodeOrVariable {
     fn from(var: Variable) -> Self {
         NamedNodeOrVariable::Variable(var)
@@ -57,6 +63,12 @@ impl From<NamedNode> for TermOrVariable {
     }
 }
 
+impl From<NamedNodeRef<'_>> for TermOrVariable {
+    fn from(node: NamedNodeRef<'_>) -> Self {
+        TermOrVariable::Term(node.into())
+    }
+}
+
 impl From<BlankNode> for TermOrVariable {
     fn from(node: BlankNode) -> Self {
         TermOrVariable::Term(node.into())
diff --git a/lib/src/sparql/eval.rs b/lib/src/sparql/eval.rs
index 0499bc6c..fda31151 100644
--- a/lib/src/sparql/eval.rs
+++ b/lib/src/sparql/eval.rs
@@ -1065,7 +1065,12 @@ where
                     let bnode =
                         BlankNode::new(self.to_simple_string(self.eval_expression(id, tuple)?)?)
                             .ok()?;
-                    Some(self.dataset.as_ref().encode_blank_node(&bnode).ok()?)
+                    Some(
+                        self.dataset
+                            .as_ref()
+                            .encode_blank_node(bnode.as_ref())
+                            .ok()?,
+                    )
                 }
                 None => Some(EncodedTerm::InlineBlankNode {
                     id: random::<u128>(),
@@ -1741,7 +1746,7 @@ where
                 put_variable_value(
                     variable,
                     &variables,
-                    encoder.encode_term(term).map_err(|e| e.into())?,
+                    encoder.encode_term(term.as_ref()).map_err(|e| e.into())?,
                     &mut encoded_terms,
                 )
             }
diff --git a/lib/src/sparql/parser.rs b/lib/src/sparql/parser.rs
index 3ebbf25c..19324b01 100644
--- a/lib/src/sparql/parser.rs
+++ b/lib/src/sparql/parser.rs
@@ -1052,7 +1052,7 @@ parser! {
         }
 
         //[78]
-        rule Verb() -> NamedNodeOrVariable = VarOrIri() / "a" { rdf::TYPE.clone().into() }
+        rule Verb() -> NamedNodeOrVariable = VarOrIri() / "a" { rdf::TYPE.into() }
 
         //[79]
         rule ObjectList() -> FocusedTriplePattern<Vec<TermOrVariable>> = o:ObjectList_item() **<1,> ("," _) {
@@ -1172,7 +1172,7 @@ parser! {
         //[94]
         rule PathPrimary() -> PropertyPath =
             v:iri() { v.into() } /
-            "a" { rdf::TYPE.clone().into() } /
+            "a" { NamedNode::from(rdf::TYPE).into() } /
             "!" _ p:PathNegatedPropertySet() { p } /
             "(" _ p:Path() _ ")" { p }
 
@@ -1209,9 +1209,9 @@ parser! {
         //[96]
         rule PathOneInPropertySet() -> Either<NamedNode,NamedNode> =
             "^" _ v:iri() { Either::Right(v) } /
-            "^" _ "a" { Either::Right(rdf::TYPE.clone()) } /
+            "^" _ "a" { Either::Right(rdf::TYPE.into()) } /
             v:iri() { Either::Left(v) } /
-            "a" { Either::Left(rdf::TYPE.clone()) }
+            "a" { Either::Left(rdf::TYPE.into()) }
 
         //[98]
         rule TriplesNode() -> FocusedTriplePattern<TermOrVariable> = Collection() / BlankNodePropertyList()
@@ -1252,11 +1252,11 @@ parser! {
         //[102]
         rule Collection() -> FocusedTriplePattern<TermOrVariable> = "(" _ o:Collection_item()+ ")" {
             let mut patterns: Vec<TriplePattern> = Vec::default();
-            let mut current_list_node = TermOrVariable::from(rdf::NIL.clone());
+            let mut current_list_node = TermOrVariable::from(rdf::NIL);
             for objWithPatterns in o.into_iter().rev() {
                 let new_blank_node = TermOrVariable::from(BlankNode::default());
-                patterns.push(TriplePattern::new(new_blank_node.clone(), rdf::FIRST.clone(), objWithPatterns.focus.clone()));
-                patterns.push(TriplePattern::new(new_blank_node.clone(), rdf::REST.clone(), current_list_node));
+                patterns.push(TriplePattern::new(new_blank_node.clone(), rdf::FIRST, objWithPatterns.focus.clone()));
+                patterns.push(TriplePattern::new(new_blank_node.clone(), rdf::REST, current_list_node));
                 current_list_node = new_blank_node;
                 patterns.extend_from_slice(&objWithPatterns.patterns);
             }
@@ -1270,11 +1270,11 @@ parser! {
         //[103]
         rule CollectionPath() -> FocusedTripleOrPathPattern<TermOrVariable> = "(" _ o:CollectionPath_item()+ _ ")" {
             let mut patterns: Vec<TripleOrPathPattern> = Vec::default();
-            let mut current_list_node = TermOrVariable::from(rdf::NIL.clone());
+            let mut current_list_node = TermOrVariable::from(rdf::NIL);
             for objWithPatterns in o.into_iter().rev() {
                 let new_blank_node = TermOrVariable::from(BlankNode::default());
-                patterns.push(TriplePattern::new(new_blank_node.clone(), rdf::FIRST.clone(), objWithPatterns.focus.clone()).into());
-                patterns.push(TriplePattern::new(new_blank_node.clone(), rdf::REST.clone(), current_list_node).into());
+                patterns.push(TriplePattern::new(new_blank_node.clone(), rdf::FIRST, objWithPatterns.focus.clone()).into());
+                patterns.push(TriplePattern::new(new_blank_node.clone(), rdf::REST, current_list_node).into());
                 current_list_node = new_blank_node;
                 patterns.extend_from_slice(&objWithPatterns.patterns);
             }
@@ -1315,7 +1315,7 @@ parser! {
             l:NumericLiteral() { l.into() } /
             l:BooleanLiteral() { l.into() } /
             b:BlankNode() { b.into() } /
-            NIL() { rdf::NIL.clone().into() }
+            NIL() { rdf::NIL.into() }
 
         //[110]
         rule Expression() -> Expression = e:ConditionalOrExpression() {e}
@@ -1523,8 +1523,8 @@ parser! {
                 Ok(value) => Ok(value.into()),
                 Err(_) => Err("Invalid xsd:double()")
             } } /
-            d:$(DECIMAL()) { Literal::new_typed_literal(d, xsd::DECIMAL.clone()) } /
-            i:$(INTEGER()) { Literal::new_typed_literal(i, xsd::INTEGER.clone()) }
+            d:$(DECIMAL()) { Literal::new_typed_literal(d, xsd::DECIMAL) } /
+            i:$(INTEGER()) { Literal::new_typed_literal(i, xsd::INTEGER) }
 
         //[132]
         rule NumericLiteralPositive() -> Literal =
@@ -1532,8 +1532,8 @@ parser! {
                 Ok(value) => Ok(value.into()),
                 Err(_) => Err("Invalid xsd:double()")
             } } /
-            d:$(DECIMAL_POSITIVE()) { Literal::new_typed_literal(d, xsd::DECIMAL.clone()) } /
-            i:$(INTEGER_POSITIVE()) { Literal::new_typed_literal(i, xsd::INTEGER.clone()) }
+            d:$(DECIMAL_POSITIVE()) { Literal::new_typed_literal(d, xsd::DECIMAL) } /
+            i:$(INTEGER_POSITIVE()) { Literal::new_typed_literal(i, xsd::INTEGER) }
 
 
         //[133]
@@ -1542,8 +1542,8 @@ parser! {
                 Ok(value) => Ok(value.into()),
                 Err(_) => Err("Invalid xsd:double()")
             } } /
-            d:$(DECIMAL_NEGATIVE()) { Literal::new_typed_literal(d, xsd::DECIMAL.clone()) } /
-            i:$(INTEGER_NEGATIVE()) { Literal::new_typed_literal(i, xsd::INTEGER.clone()) }
+            d:$(DECIMAL_NEGATIVE()) { Literal::new_typed_literal(d, xsd::DECIMAL) } /
+            i:$(INTEGER_NEGATIVE()) { Literal::new_typed_literal(i, xsd::INTEGER) }
 
         //[134]
         rule BooleanLiteral() -> Literal =
diff --git a/lib/src/sparql/plan_builder.rs b/lib/src/sparql/plan_builder.rs
index 6ade4421..ad8339d6 100644
--- a/lib/src/sparql/plan_builder.rs
+++ b/lib/src/sparql/plan_builder.rs
@@ -992,17 +992,20 @@ impl<E: WriteEncoder<Error = EvaluationError>> PlanBuilder<E> {
 
     fn build_named_node(
         &mut self,
-        term: &NamedNode,
+        node: &NamedNode,
     ) -> Result<EncodedTerm<E::StrId>, EvaluationError> {
-        Ok(self.encoder.encode_named_node(term)?)
+        Ok(self.encoder.encode_named_node(node.as_ref())?)
     }
 
-    fn build_literal(&mut self, term: &Literal) -> Result<EncodedTerm<E::StrId>, EvaluationError> {
-        Ok(self.encoder.encode_literal(term)?)
+    fn build_literal(
+        &mut self,
+        literal: &Literal,
+    ) -> Result<EncodedTerm<E::StrId>, EvaluationError> {
+        Ok(self.encoder.encode_literal(literal.as_ref())?)
     }
 
     fn build_term(&mut self, term: &Term) -> Result<EncodedTerm<E::StrId>, EvaluationError> {
-        Ok(self.encoder.encode_term(term)?)
+        Ok(self.encoder.encode_term(term.as_ref())?)
     }
 }
 
diff --git a/lib/src/store/memory.rs b/lib/src/store/memory.rs
index 20eaf402..8c03c2b7 100644
--- a/lib/src/store/memory.rs
+++ b/lib/src/store/memory.rs
@@ -40,7 +40,7 @@ use std::{fmt, io};
 /// store.insert(quad.clone());
 ///
 /// // quad filter
-/// let results: Vec<Quad> = store.quads_for_pattern(Some(&ex.clone().into()), None, None, None).collect();
+/// let results: Vec<Quad> = store.quads_for_pattern(Some(ex.as_ref().into()), None, None, None).collect();
 /// assert_eq!(vec![quad], results);
 ///
 /// // SPARQL query
@@ -168,10 +168,10 @@ impl MemoryStore {
     /// ```
     pub fn quads_for_pattern(
         &self,
-        subject: Option<&NamedOrBlankNode>,
-        predicate: Option<&NamedNode>,
-        object: Option<&Term>,
-        graph_name: Option<&GraphName>,
+        subject: Option<NamedOrBlankNodeRef<'_>>,
+        predicate: Option<NamedNodeRef<'_>>,
+        object: Option<TermRef<'_>>,
+        graph_name: Option<GraphNameRef<'_>>,
     ) -> impl Iterator<Item = Quad> {
         let quads = if let Some((subject, predicate, object, graph_name)) =
             get_encoded_quad_pattern(self, subject, predicate, object, graph_name)
@@ -188,8 +188,8 @@ impl MemoryStore {
     }
 
     /// Checks if this store contains a given quad
-    pub fn contains(&self, quad: &Quad) -> bool {
-        self.get_encoded_quad(quad)
+    pub fn contains<'a>(&self, quad: impl Into<QuadRef<'a>>) -> bool {
+        self.get_encoded_quad(quad.into())
             .unwrap_infallible()
             .map_or(false, |q| self.contains_encoded(&q))
     }
@@ -250,11 +250,11 @@ impl MemoryStore {
         for op in transaction.ops {
             match op {
                 TransactionOp::Insert(quad) => {
-                    let quad = this.encode_quad(&quad).unwrap_infallible();
+                    let quad = this.encode_quad(quad.as_ref()).unwrap_infallible();
                     indexes.insert_encoded(&quad).unwrap_infallible()
                 }
                 TransactionOp::Delete(quad) => {
-                    let quad = this.encode_quad(&quad).unwrap_infallible();
+                    let quad = this.encode_quad(quad.as_ref()).unwrap_infallible();
                     indexes.remove_encoded(&quad).unwrap_infallible()
                 }
             }
@@ -285,15 +285,15 @@ impl MemoryStore {
     ///
     /// Errors related to parameter validation like the base IRI use the `INVALID_INPUT` error kind.
     /// Errors related to a bad syntax in the loaded file use the `INVALID_DATA` error kind.
-    pub fn load_graph(
+    pub fn load_graph<'a>(
         &self,
         reader: impl BufRead,
         format: GraphFormat,
-        to_graph_name: &GraphName,
+        to_graph_name: impl Into<GraphNameRef<'a>>,
         base_iri: Option<&str>,
     ) -> Result<(), io::Error> {
         let mut store = self;
-        load_graph(&mut store, reader, format, to_graph_name, base_iri)?;
+        load_graph(&mut store, reader, format, to_graph_name.into(), base_iri)?;
         Ok(())
     }
 
@@ -335,13 +335,13 @@ impl MemoryStore {
     #[allow(clippy::needless_pass_by_value)]
     pub fn insert(&self, quad: Quad) {
         let mut this = self;
-        let quad = this.encode_quad(&quad).unwrap_infallible();
+        let quad = this.encode_quad(quad.as_ref()).unwrap_infallible();
         this.insert_encoded(&quad).unwrap_infallible();
     }
 
     /// Removes a quad from this store.
-    pub fn remove(&self, quad: &Quad) {
-        if let Some(quad) = self.get_encoded_quad(quad).unwrap_infallible() {
+    pub fn remove<'a>(&self, quad: impl Into<QuadRef<'a>>) {
+        if let Some(quad) = self.get_encoded_quad(quad.into()).unwrap_infallible() {
             let mut this = self;
             this.remove_encoded(&quad).unwrap_infallible();
         }
@@ -378,14 +378,14 @@ impl MemoryStore {
     ///
     /// Errors related to parameter validation like the base IRI use the `INVALID_INPUT` error kind.
     /// Errors related to a bad syntax in the loaded file use the `INVALID_DATA` error kind.
-    pub fn dump_graph(
+    pub fn dump_graph<'a>(
         &self,
         writer: impl Write,
         format: GraphFormat,
-        from_graph_name: &GraphName,
+        from_graph_name: impl Into<GraphNameRef<'a>>,
     ) -> Result<(), io::Error> {
         dump_graph(
-            self.quads_for_pattern(None, None, None, Some(from_graph_name))
+            self.quads_for_pattern(None, None, None, Some(from_graph_name.into()))
                 .map(|q| Ok(q.into())),
             writer,
             format,
@@ -973,13 +973,14 @@ impl MemoryTransaction {
     /// assert_eq!(vec![Quad::new(ex.clone(), ex.clone(), ex.clone(), None)], results);
     /// # Result::<_, oxigraph::sparql::EvaluationError>::Ok(())
     /// ```
-    pub fn load_graph(
+    pub fn load_graph<'a>(
         &mut self,
         reader: impl BufRead,
         format: GraphFormat,
-        to_graph_name: &GraphName,
+        to_graph_name: impl Into<GraphNameRef<'a>>,
         base_iri: Option<&str>,
     ) -> Result<(), io::Error> {
+        let to_graph_name = to_graph_name.into();
         let mut parser = GraphParser::from_format(format);
         if let Some(base_iri) = base_iri {
             parser = parser
@@ -987,9 +988,8 @@ impl MemoryTransaction {
                 .map_err(invalid_input_error)?;
         }
         for triple in parser.read_triples(reader)? {
-            self.ops.push(TransactionOp::Insert(
-                triple?.in_graph(to_graph_name.clone()),
-            ));
+            self.ops
+                .push(TransactionOp::Insert(triple?.in_graph(to_graph_name)));
         }
         Ok(())
     }
diff --git a/lib/src/store/mod.rs b/lib/src/store/mod.rs
index 6f342249..147c47ad 100644
--- a/lib/src/store/mod.rs
+++ b/lib/src/store/mod.rs
@@ -17,16 +17,12 @@ pub use crate::store::rocksdb::RocksDbStore;
 pub use crate::store::sled::SledStore;
 
 use crate::error::{invalid_data_error, invalid_input_error};
-use crate::io::{DatasetFormat, GraphFormat};
+use crate::io::{DatasetFormat, DatasetSerializer, GraphFormat, GraphSerializer};
 use crate::model::*;
 use crate::store::numeric_encoder::*;
-use rio_api::formatter::{QuadsFormatter, TriplesFormatter};
 use rio_api::parser::{QuadsParser, TriplesParser};
-use rio_turtle::{
-    NQuadsFormatter, NQuadsParser, NTriplesFormatter, NTriplesParser, TriGFormatter, TriGParser,
-    TurtleError, TurtleFormatter, TurtleParser,
-};
-use rio_xml::{RdfXmlError, RdfXmlFormatter, RdfXmlParser};
+use rio_turtle::{NQuadsParser, NTriplesParser, TriGParser, TurtleError, TurtleParser};
+use rio_xml::{RdfXmlError, RdfXmlParser};
 use std::collections::HashMap;
 use std::convert::Infallible;
 use std::io;
@@ -55,7 +51,7 @@ fn load_graph<S: WritableEncodedStore + StrContainer>(
     store: &mut S,
     reader: impl BufRead,
     format: GraphFormat,
-    to_graph_name: &GraphName,
+    to_graph_name: GraphNameRef<'_>,
     base_iri: Option<&str>,
 ) -> Result<(), StoreOrParseError<S::Error, io::Error>> {
     let base_iri = base_iri.unwrap_or("");
@@ -75,7 +71,7 @@ fn load_graph<S: WritableEncodedStore + StrContainer>(
 fn load_from_triple_parser<S: WritableEncodedStore + StrContainer, P: TriplesParser>(
     store: &mut S,
     parser: Result<P, P::Error>,
-    to_graph_name: &GraphName,
+    to_graph_name: GraphNameRef<'_>,
 ) -> Result<(), StoreOrParseError<S::Error, io::Error>>
 where
     StoreOrParseError<S::Error, P::Error>: From<P::Error>,
@@ -107,34 +103,11 @@ fn dump_graph(
     writer: impl Write,
     format: GraphFormat,
 ) -> Result<(), io::Error> {
-    match format {
-        GraphFormat::NTriples => {
-            let mut formatter = NTriplesFormatter::new(writer);
-            for triple in triples {
-                formatter.format(&(&triple?).into())?;
-            }
-            formatter.finish();
-        }
-        GraphFormat::Turtle => {
-            let mut formatter = TurtleFormatter::new(writer);
-            for triple in triples {
-                formatter.format(&(&triple?).into())?;
-            }
-            formatter.finish()?;
-        }
-        GraphFormat::RdfXml => {
-            let mut formatter = RdfXmlFormatter::new(writer).map_err(map_xml_err)?;
-            for triple in triples {
-                formatter.format(&(&triple?).into()).map_err(map_xml_err)?;
-            }
-            formatter.finish().map_err(map_xml_err)?;
-        }
+    let mut writer = GraphSerializer::from_format(format).triple_writer(writer)?;
+    for triple in triples {
+        writer.write(&triple?)?;
     }
-    Ok(())
-}
-
-fn map_xml_err(e: RdfXmlError) -> io::Error {
-    io::Error::new(io::ErrorKind::Other, e) // TODO: drop
+    writer.finish()
 }
 
 fn load_dataset<S: WritableEncodedStore + StrContainer>(
@@ -181,23 +154,11 @@ fn dump_dataset(
     writer: impl Write,
     format: DatasetFormat,
 ) -> Result<(), io::Error> {
-    match format {
-        DatasetFormat::NQuads => {
-            let mut formatter = NQuadsFormatter::new(writer);
-            for quad in quads {
-                formatter.format(&(&quad?).into())?;
-            }
-            formatter.finish();
-        }
-        DatasetFormat::TriG => {
-            let mut formatter = TriGFormatter::new(writer);
-            for quad in quads {
-                formatter.format(&(&quad?).into())?;
-            }
-            formatter.finish()?;
-        }
+    let mut writer = DatasetSerializer::from_format(format).quad_writer(writer)?;
+    for quad in quads {
+        writer.write(&quad?)?;
     }
-    Ok(())
+    writer.finish()
 }
 
 enum StoreOrParseError<S, P> {
@@ -249,10 +210,10 @@ type QuadPattern<I> = (
 
 fn get_encoded_quad_pattern<E: ReadEncoder>(
     encoder: &E,
-    subject: Option<&NamedOrBlankNode>,
-    predicate: Option<&NamedNode>,
-    object: Option<&Term>,
-    graph_name: Option<&GraphName>,
+    subject: Option<NamedOrBlankNodeRef<'_>>,
+    predicate: Option<NamedNodeRef<'_>>,
+    object: Option<TermRef<'_>>,
+    graph_name: Option<GraphNameRef<'_>>,
 ) -> Result<Option<QuadPattern<E::StrId>>, E::Error> {
     Ok(Some((
         if let Some(subject) = transpose(
diff --git a/lib/src/store/numeric_encoder.rs b/lib/src/store/numeric_encoder.rs
index 9013ad9b..1ea0aafc 100644
--- a/lib/src/store/numeric_encoder.rs
+++ b/lib/src/store/numeric_encoder.rs
@@ -787,7 +787,7 @@ impl StrContainer for MemoryStrStore {
 pub(crate) trait ReadEncoder: WithStoreError {
     fn get_encoded_named_node(
         &self,
-        named_node: &NamedNode,
+        named_node: NamedNodeRef<'_>,
     ) -> Result<Option<EncodedTerm<Self::StrId>>, Self::Error> {
         Ok(Some(EncodedTerm::NamedNode {
             iri_id: if let Some(iri_id) = self.get_encoded_str(named_node.as_str())? {
@@ -800,7 +800,7 @@ pub(crate) trait ReadEncoder: WithStoreError {
 
     fn get_encoded_blank_node(
         &self,
-        blank_node: &BlankNode,
+        blank_node: BlankNodeRef<'_>,
     ) -> Result<Option<EncodedTerm<Self::StrId>>, Self::Error> {
         Ok(Some(if let Some(id) = blank_node.id() {
             EncodedTerm::InlineBlankNode { id }
@@ -817,7 +817,7 @@ pub(crate) trait ReadEncoder: WithStoreError {
 
     fn get_encoded_literal(
         &self,
-        literal: &Literal,
+        literal: LiteralRef<'_>,
     ) -> Result<Option<EncodedTerm<Self::StrId>>, Self::Error> {
         Ok(Some(
             match match literal.datatype().as_str() {
@@ -905,57 +905,57 @@ pub(crate) trait ReadEncoder: WithStoreError {
 
     fn get_encoded_named_or_blank_node(
         &self,
-        term: &NamedOrBlankNode,
+        term: NamedOrBlankNodeRef<'_>,
     ) -> Result<Option<EncodedTerm<Self::StrId>>, Self::Error> {
         match term {
-            NamedOrBlankNode::NamedNode(named_node) => self.get_encoded_named_node(named_node),
-            NamedOrBlankNode::BlankNode(blank_node) => self.get_encoded_blank_node(blank_node),
+            NamedOrBlankNodeRef::NamedNode(named_node) => self.get_encoded_named_node(named_node),
+            NamedOrBlankNodeRef::BlankNode(blank_node) => self.get_encoded_blank_node(blank_node),
         }
     }
 
     fn get_encoded_term(
         &self,
-        term: &Term,
+        term: TermRef<'_>,
     ) -> Result<Option<EncodedTerm<Self::StrId>>, Self::Error> {
         match term {
-            Term::NamedNode(named_node) => self.get_encoded_named_node(named_node),
-            Term::BlankNode(blank_node) => self.get_encoded_blank_node(blank_node),
-            Term::Literal(literal) => self.get_encoded_literal(literal),
+            TermRef::NamedNode(named_node) => self.get_encoded_named_node(named_node),
+            TermRef::BlankNode(blank_node) => self.get_encoded_blank_node(blank_node),
+            TermRef::Literal(literal) => self.get_encoded_literal(literal),
         }
     }
 
     fn get_encoded_graph_name(
         &self,
-        name: &GraphName,
+        name: GraphNameRef<'_>,
     ) -> Result<Option<EncodedTerm<Self::StrId>>, Self::Error> {
         match name {
-            GraphName::NamedNode(named_node) => self.get_encoded_named_node(named_node),
-            GraphName::BlankNode(blank_node) => self.get_encoded_blank_node(blank_node),
-            GraphName::DefaultGraph => Ok(Some(EncodedTerm::DefaultGraph)),
+            GraphNameRef::NamedNode(named_node) => self.get_encoded_named_node(named_node),
+            GraphNameRef::BlankNode(blank_node) => self.get_encoded_blank_node(blank_node),
+            GraphNameRef::DefaultGraph => Ok(Some(EncodedTerm::DefaultGraph)),
         }
     }
 
     fn get_encoded_quad(
         &self,
-        quad: &Quad,
+        quad: QuadRef<'_>,
     ) -> Result<Option<EncodedQuad<Self::StrId>>, Self::Error> {
         Ok(Some(EncodedQuad {
-            subject: if let Some(subject) = self.get_encoded_named_or_blank_node(&quad.subject)? {
+            subject: if let Some(subject) = self.get_encoded_named_or_blank_node(quad.subject)? {
                 subject
             } else {
                 return Ok(None);
             },
-            predicate: if let Some(predicate) = self.get_encoded_named_node(&quad.predicate)? {
+            predicate: if let Some(predicate) = self.get_encoded_named_node(quad.predicate)? {
                 predicate
             } else {
                 return Ok(None);
             },
-            object: if let Some(object) = self.get_encoded_term(&quad.object)? {
+            object: if let Some(object) = self.get_encoded_term(quad.object)? {
                 object
             } else {
                 return Ok(None);
             },
-            graph_name: if let Some(graph_name) = self.get_encoded_graph_name(&quad.graph_name)? {
+            graph_name: if let Some(graph_name) = self.get_encoded_graph_name(quad.graph_name)? {
                 graph_name
             } else {
                 return Ok(None);
@@ -976,14 +976,14 @@ impl<S: StrLookup> ReadEncoder for S {
 pub(crate) trait WriteEncoder: WithStoreError {
     fn encode_named_node(
         &mut self,
-        named_node: &NamedNode,
+        named_node: NamedNodeRef<'_>,
     ) -> Result<EncodedTerm<Self::StrId>, Self::Error> {
         self.encode_rio_named_node(named_node.into())
     }
 
     fn encode_blank_node(
         &mut self,
-        blank_node: &BlankNode,
+        blank_node: BlankNodeRef<'_>,
     ) -> Result<EncodedTerm<Self::StrId>, Self::Error> {
         if let Some(id) = blank_node.id() {
             Ok(EncodedTerm::InlineBlankNode { id })
@@ -996,58 +996,58 @@ pub(crate) trait WriteEncoder: WithStoreError {
 
     fn encode_literal(
         &mut self,
-        literal: &Literal,
+        literal: LiteralRef<'_>,
     ) -> Result<EncodedTerm<Self::StrId>, Self::Error> {
         self.encode_rio_literal(literal.into())
     }
 
     fn encode_named_or_blank_node(
         &mut self,
-        term: &NamedOrBlankNode,
+        term: NamedOrBlankNodeRef<'_>,
     ) -> Result<EncodedTerm<Self::StrId>, Self::Error> {
         match term {
-            NamedOrBlankNode::NamedNode(named_node) => self.encode_named_node(named_node),
-            NamedOrBlankNode::BlankNode(blank_node) => self.encode_blank_node(blank_node),
+            NamedOrBlankNodeRef::NamedNode(named_node) => self.encode_named_node(named_node),
+            NamedOrBlankNodeRef::BlankNode(blank_node) => self.encode_blank_node(blank_node),
         }
     }
 
-    fn encode_term(&mut self, term: &Term) -> Result<EncodedTerm<Self::StrId>, Self::Error> {
+    fn encode_term(&mut self, term: TermRef<'_>) -> Result<EncodedTerm<Self::StrId>, Self::Error> {
         match term {
-            Term::NamedNode(named_node) => self.encode_named_node(named_node),
-            Term::BlankNode(blank_node) => self.encode_blank_node(blank_node),
-            Term::Literal(literal) => self.encode_literal(literal),
+            TermRef::NamedNode(named_node) => self.encode_named_node(named_node),
+            TermRef::BlankNode(blank_node) => self.encode_blank_node(blank_node),
+            TermRef::Literal(literal) => self.encode_literal(literal),
         }
     }
 
     fn encode_graph_name(
         &mut self,
-        name: &GraphName,
+        name: GraphNameRef<'_>,
     ) -> Result<EncodedTerm<Self::StrId>, Self::Error> {
         match name {
-            GraphName::NamedNode(named_node) => self.encode_named_node(named_node),
-            GraphName::BlankNode(blank_node) => self.encode_blank_node(blank_node),
-            GraphName::DefaultGraph => Ok(EncodedTerm::DefaultGraph),
+            GraphNameRef::NamedNode(named_node) => self.encode_named_node(named_node),
+            GraphNameRef::BlankNode(blank_node) => self.encode_blank_node(blank_node),
+            GraphNameRef::DefaultGraph => Ok(EncodedTerm::DefaultGraph),
         }
     }
 
-    fn encode_quad(&mut self, quad: &Quad) -> Result<EncodedQuad<Self::StrId>, Self::Error> {
+    fn encode_quad(&mut self, quad: QuadRef<'_>) -> Result<EncodedQuad<Self::StrId>, Self::Error> {
         Ok(EncodedQuad {
-            subject: self.encode_named_or_blank_node(&quad.subject)?,
-            predicate: self.encode_named_node(&quad.predicate)?,
-            object: self.encode_term(&quad.object)?,
-            graph_name: self.encode_graph_name(&quad.graph_name)?,
+            subject: self.encode_named_or_blank_node(quad.subject)?,
+            predicate: self.encode_named_node(quad.predicate)?,
+            object: self.encode_term(quad.object)?,
+            graph_name: self.encode_graph_name(quad.graph_name)?,
         })
     }
 
     fn encode_triple_in_graph(
         &mut self,
-        triple: &Triple,
+        triple: TripleRef<'_>,
         graph_name: EncodedTerm<Self::StrId>,
     ) -> Result<EncodedQuad<Self::StrId>, Self::Error> {
         Ok(EncodedQuad {
-            subject: self.encode_named_or_blank_node(&triple.subject)?,
-            predicate: self.encode_named_node(&triple.predicate)?,
-            object: self.encode_term(&triple.object)?,
+            subject: self.encode_named_or_blank_node(triple.subject)?,
+            predicate: self.encode_named_node(triple.predicate)?,
+            object: self.encode_term(triple.object)?,
             graph_name,
         })
     }
@@ -1433,16 +1433,19 @@ fn test_encoding() {
         Literal::new_language_tagged_literal("foo-FR", "FR")
             .unwrap()
             .into(),
-        Literal::new_typed_literal("-1.32", xsd::DECIMAL.clone()).into(),
-        Literal::new_typed_literal("2020-01-01T01:01:01Z", xsd::DATE_TIME.clone()).into(),
-        Literal::new_typed_literal("2020-01-01", xsd::DATE.clone()).into(),
-        Literal::new_typed_literal("01:01:01Z", xsd::TIME.clone()).into(),
-        Literal::new_typed_literal("PT1S", xsd::DURATION.clone()).into(),
+        Literal::new_typed_literal("-1.32", xsd::DECIMAL).into(),
+        Literal::new_typed_literal("2020-01-01T01:01:01Z", xsd::DATE_TIME).into(),
+        Literal::new_typed_literal("2020-01-01", xsd::DATE).into(),
+        Literal::new_typed_literal("01:01:01Z", xsd::TIME).into(),
+        Literal::new_typed_literal("PT1S", xsd::DURATION).into(),
         Literal::new_typed_literal("-foo", NamedNode::new_unchecked("http://foo.com")).into(),
     ];
     for term in terms {
-        let encoded = store.encode_term(&term).unwrap();
-        assert_eq!(Some(encoded), store.get_encoded_term(&term).unwrap());
+        let encoded = store.encode_term(term.as_ref()).unwrap();
+        assert_eq!(
+            Some(encoded),
+            store.get_encoded_term(term.as_ref()).unwrap()
+        );
         assert_eq!(term, store.decode_term(encoded).unwrap());
     }
 }
diff --git a/lib/src/store/rocksdb.rs b/lib/src/store/rocksdb.rs
index b5a62f75..4f2dfeab 100644
--- a/lib/src/store/rocksdb.rs
+++ b/lib/src/store/rocksdb.rs
@@ -125,10 +125,10 @@ impl RocksDbStore {
     /// See `MemoryStore` for a usage example.
     pub fn quads_for_pattern(
         &self,
-        subject: Option<&NamedOrBlankNode>,
-        predicate: Option<&NamedNode>,
-        object: Option<&Term>,
-        graph_name: Option<&GraphName>,
+        subject: Option<NamedOrBlankNodeRef<'_>>,
+        predicate: Option<NamedNodeRef<'_>>,
+        object: Option<TermRef<'_>>,
+        graph_name: Option<GraphNameRef<'_>>,
     ) -> impl Iterator<Item = Result<Quad, io::Error>> {
         match get_encoded_quad_pattern(self, subject, predicate, object, graph_name) {
             Ok(Some((subject, predicate, object, graph_name))) => QuadsIter::Quads {
@@ -141,8 +141,8 @@ impl RocksDbStore {
     }
 
     /// Checks if this store contains a given quad
-    pub fn contains(&self, quad: &Quad) -> Result<bool, io::Error> {
-        if let Some(quad) = self.get_encoded_quad(quad)? {
+    pub fn contains<'a>(&self, quad: impl Into<QuadRef<'a>>) -> Result<bool, io::Error> {
+        if let Some(quad) = self.get_encoded_quad(quad.into())? {
             self.contains_encoded(&quad)
         } else {
             Ok(false)
@@ -194,15 +194,21 @@ impl RocksDbStore {
     /// Errors related to parameter validation like the base IRI use the `INVALID_INPUT` error kind.
     /// Errors related to a bad syntax in the loaded file use the `INVALID_DATA` error kind.
     /// Errors related to data loading into the store use the other error kinds.
-    pub fn load_graph(
+    pub fn load_graph<'a>(
         &self,
         reader: impl BufRead,
         format: GraphFormat,
-        to_graph_name: &GraphName,
+        to_graph_name: impl Into<GraphNameRef<'a>>,
         base_iri: Option<&str>,
     ) -> Result<(), io::Error> {
         let mut transaction = self.auto_batch_writer();
-        load_graph(&mut transaction, reader, format, to_graph_name, base_iri)?;
+        load_graph(
+            &mut transaction,
+            reader,
+            format,
+            to_graph_name.into(),
+            base_iri,
+        )?;
         Ok(transaction.apply()?)
     }
 
@@ -228,16 +234,16 @@ impl RocksDbStore {
     }
 
     /// Adds a quad to this store.
-    pub fn insert(&self, quad: &Quad) -> Result<(), io::Error> {
+    pub fn insert<'a>(&self, quad: impl Into<QuadRef<'a>>) -> Result<(), io::Error> {
         let mut transaction = self.auto_batch_writer();
-        let quad = transaction.encode_quad(quad)?;
+        let quad = transaction.encode_quad(quad.into())?;
         transaction.insert_encoded(&quad)?;
         transaction.apply()
     }
 
     /// Removes a quad from this store.
-    pub fn remove(&self, quad: &Quad) -> Result<(), io::Error> {
-        if let Some(quad) = self.get_encoded_quad(quad)? {
+    pub fn remove<'a>(&self, quad: impl Into<QuadRef<'a>>) -> Result<(), io::Error> {
+        if let Some(quad) = self.get_encoded_quad(quad.into())? {
             let mut transaction = self.auto_batch_writer();
             transaction.remove_encoded(&quad)?;
             transaction.apply()
@@ -249,14 +255,14 @@ impl RocksDbStore {
     /// Dumps a store graph into a file.
     ///    
     /// See `MemoryStore` for a usage example.
-    pub fn dump_graph(
+    pub fn dump_graph<'a>(
         &self,
         writer: impl Write,
         format: GraphFormat,
-        from_graph_name: &GraphName,
+        from_graph_name: impl Into<GraphNameRef<'a>>,
     ) -> Result<(), io::Error> {
         dump_graph(
-            self.quads_for_pattern(None, None, None, Some(from_graph_name))
+            self.quads_for_pattern(None, None, None, Some(from_graph_name.into()))
                 .map(|q| Ok(q?.into())),
             writer,
             format,
@@ -696,14 +702,14 @@ impl RocksDbTransaction<'_> {
     ///
     /// Errors related to parameter validation like the base IRI use the `INVALID_INPUT` error kind.
     /// Errors related to a bad syntax in the loaded file use the `INVALID_DATA` error kind.
-    pub fn load_graph(
+    pub fn load_graph<'a>(
         &mut self,
         reader: impl BufRead,
         syntax: GraphFormat,
-        to_graph_name: &GraphName,
+        to_graph_name: impl Into<GraphNameRef<'a>>,
         base_iri: Option<&str>,
     ) -> Result<(), io::Error> {
-        load_graph(self, reader, syntax, to_graph_name, base_iri)?;
+        load_graph(self, reader, syntax, to_graph_name.into(), base_iri)?;
         Ok(())
     }
 
@@ -728,15 +734,15 @@ impl RocksDbTransaction<'_> {
     }
 
     /// Adds a quad to this store during the transaction.
-    pub fn insert(&mut self, quad: &Quad) -> Result<(), io::Error> {
-        let quad = self.encode_quad(quad)?;
+    pub fn insert<'a>(&mut self, quad: impl Into<QuadRef<'a>>) -> Result<(), io::Error> {
+        let quad = self.encode_quad(quad.into())?;
         self.insert_encoded(&quad)
     }
 
     /// Removes a quad from this store during the transaction.
-    pub fn remove(&mut self, quad: &Quad) -> Result<(), io::Error> {
+    pub fn remove<'a>(&mut self, quad: impl Into<QuadRef<'a>>) -> Result<(), io::Error> {
         // Works because all strings could be encoded
-        if let Some(quad) = self.get_encoded_quad(quad).unwrap() {
+        if let Some(quad) = self.get_encoded_quad(quad.into()).unwrap() {
             self.remove_encoded(&quad)
         } else {
             Ok(())
@@ -1060,29 +1066,34 @@ fn store() -> Result<(), io::Error> {
         );
         assert_eq!(
             store
-                .quads_for_pattern(Some(&main_s), None, None, None)
+                .quads_for_pattern(Some(main_s.as_ref()), None, None, None)
                 .collect::<Result<Vec<_>, _>>()?,
             all_o
         );
         assert_eq!(
             store
-                .quads_for_pattern(Some(&main_s), Some(&main_p), None, None)
+                .quads_for_pattern(Some(main_s.as_ref()), Some(main_p.as_ref()), None, None)
                 .collect::<Result<Vec<_>, _>>()?,
             all_o
         );
         assert_eq!(
             store
-                .quads_for_pattern(Some(&main_s), Some(&main_p), Some(&main_o), None)
+                .quads_for_pattern(
+                    Some(main_s.as_ref()),
+                    Some(main_p.as_ref()),
+                    Some(main_o.as_ref()),
+                    None
+                )
                 .collect::<Result<Vec<_>, _>>()?,
             target
         );
         assert_eq!(
             store
                 .quads_for_pattern(
-                    Some(&main_s),
-                    Some(&main_p),
-                    Some(&main_o),
-                    Some(&GraphName::DefaultGraph)
+                    Some(main_s.as_ref()),
+                    Some(main_p.as_ref()),
+                    Some(main_o.as_ref()),
+                    Some(GraphNameRef::DefaultGraph)
                 )
                 .collect::<Result<Vec<_>, _>>()?,
             target
@@ -1090,58 +1101,63 @@ fn store() -> Result<(), io::Error> {
         assert_eq!(
             store
                 .quads_for_pattern(
-                    Some(&main_s),
-                    Some(&main_p),
+                    Some(main_s.as_ref()),
+                    Some(main_p.as_ref()),
                     None,
-                    Some(&GraphName::DefaultGraph)
+                    Some(GraphNameRef::DefaultGraph)
                 )
                 .collect::<Result<Vec<_>, _>>()?,
             all_o
         );
         assert_eq!(
             store
-                .quads_for_pattern(Some(&main_s), None, Some(&main_o), None)
+                .quads_for_pattern(Some(main_s.as_ref()), None, Some(main_o.as_ref()), None)
                 .collect::<Result<Vec<_>, _>>()?,
             target
         );
         assert_eq!(
             store
                 .quads_for_pattern(
-                    Some(&main_s),
+                    Some(main_s.as_ref()),
                     None,
-                    Some(&main_o),
-                    Some(&GraphName::DefaultGraph)
+                    Some(main_o.as_ref()),
+                    Some(GraphNameRef::DefaultGraph)
                 )
                 .collect::<Result<Vec<_>, _>>()?,
             target
         );
         assert_eq!(
             store
-                .quads_for_pattern(Some(&main_s), None, None, Some(&GraphName::DefaultGraph))
+                .quads_for_pattern(
+                    Some(main_s.as_ref()),
+                    None,
+                    None,
+                    Some(GraphNameRef::DefaultGraph)
+                )
                 .collect::<Result<Vec<_>, _>>()?,
             all_o
         );
         assert_eq!(
             store
-                .quads_for_pattern(None, Some(&main_p), None, None)
+                .quads_for_pattern(None, Some(main_p.as_ref()), None, None)
                 .collect::<Result<Vec<_>, _>>()?,
             all_o
         );
         assert_eq!(
             store
-                .quads_for_pattern(None, Some(&main_p), Some(&main_o), None)
+                .quads_for_pattern(None, Some(main_p.as_ref()), Some(main_o.as_ref()), None)
                 .collect::<Result<Vec<_>, _>>()?,
             target
         );
         assert_eq!(
             store
-                .quads_for_pattern(None, None, Some(&main_o), None)
+                .quads_for_pattern(None, None, Some(main_o.as_ref()), None)
                 .collect::<Result<Vec<_>, _>>()?,
             target
         );
         assert_eq!(
             store
-                .quads_for_pattern(None, None, None, Some(&GraphName::DefaultGraph))
+                .quads_for_pattern(None, None, None, Some(GraphNameRef::DefaultGraph))
                 .collect::<Result<Vec<_>, _>>()?,
             all_o
         );
@@ -1149,9 +1165,9 @@ fn store() -> Result<(), io::Error> {
             store
                 .quads_for_pattern(
                     None,
-                    Some(&main_p),
-                    Some(&main_o),
-                    Some(&GraphName::DefaultGraph)
+                    Some(main_p.as_ref()),
+                    Some(main_o.as_ref()),
+                    Some(GraphNameRef::DefaultGraph)
                 )
                 .collect::<Result<Vec<_>, _>>()?,
             target
diff --git a/lib/src/store/sled.rs b/lib/src/store/sled.rs
index d9d5fdcd..3a8f8d50 100644
--- a/lib/src/store/sled.rs
+++ b/lib/src/store/sled.rs
@@ -126,10 +126,10 @@ impl SledStore {
     /// See `MemoryStore` for a usage example.
     pub fn quads_for_pattern(
         &self,
-        subject: Option<&NamedOrBlankNode>,
-        predicate: Option<&NamedNode>,
-        object: Option<&Term>,
-        graph_name: Option<&GraphName>,
+        subject: Option<NamedOrBlankNodeRef<'_>>,
+        predicate: Option<NamedNodeRef<'_>>,
+        object: Option<TermRef<'_>>,
+        graph_name: Option<GraphNameRef<'_>>,
     ) -> impl Iterator<Item = Result<Quad, io::Error>> {
         match get_encoded_quad_pattern(self, subject, predicate, object, graph_name) {
             Ok(Some((subject, predicate, object, graph_name))) => QuadsIter::Quads {
@@ -142,8 +142,8 @@ impl SledStore {
     }
 
     /// Checks if this store contains a given quad
-    pub fn contains(&self, quad: &Quad) -> Result<bool, io::Error> {
-        if let Some(quad) = self.get_encoded_quad(quad)? {
+    pub fn contains<'a>(&self, quad: impl Into<QuadRef<'a>>) -> Result<bool, io::Error> {
+        if let Some(quad) = self.get_encoded_quad(quad.into())? {
             self.contains_encoded(&quad)
         } else {
             Ok(false)
@@ -205,15 +205,15 @@ impl SledStore {
     /// Errors related to parameter validation like the base IRI use the `INVALID_INPUT` error kind.
     /// Errors related to a bad syntax in the loaded file use the `INVALID_DATA` error kind.
     /// Errors related to data loading into the store use the other error kinds.
-    pub fn load_graph(
+    pub fn load_graph<'a>(
         &self,
         reader: impl BufRead,
         format: GraphFormat,
-        to_graph_name: &GraphName,
+        to_graph_name: impl Into<GraphNameRef<'a>>,
         base_iri: Option<&str>,
     ) -> Result<(), io::Error> {
         let mut this = self;
-        load_graph(&mut this, reader, format, to_graph_name, base_iri)?;
+        load_graph(&mut this, reader, format, to_graph_name.into(), base_iri)?;
         Ok(())
     }
 
@@ -239,15 +239,15 @@ impl SledStore {
     }
 
     /// Adds a quad to this store.
-    pub fn insert(&self, quad: &Quad) -> Result<(), io::Error> {
+    pub fn insert<'a>(&self, quad: impl Into<QuadRef<'a>>) -> Result<(), io::Error> {
         let mut this = self;
-        let quad = this.encode_quad(quad)?;
+        let quad = this.encode_quad(quad.into())?;
         this.insert_encoded(&quad)
     }
 
     /// Removes a quad from this store.
-    pub fn remove(&self, quad: &Quad) -> Result<(), io::Error> {
-        if let Some(quad) = self.get_encoded_quad(quad)? {
+    pub fn remove<'a>(&self, quad: impl Into<QuadRef<'a>>) -> Result<(), io::Error> {
+        if let Some(quad) = self.get_encoded_quad(quad.into())? {
             let mut this = self;
             this.remove_encoded(&quad)
         } else {
@@ -258,14 +258,14 @@ impl SledStore {
     /// Dumps a store graph into a file.
     ///    
     /// See `MemoryStore` for a usage example.
-    pub fn dump_graph(
+    pub fn dump_graph<'a>(
         &self,
         writer: impl Write,
         format: GraphFormat,
-        from_graph_name: &GraphName,
+        from_graph_name: impl Into<GraphNameRef<'a>>,
     ) -> Result<(), io::Error> {
         dump_graph(
-            self.quads_for_pattern(None, None, None, Some(from_graph_name))
+            self.quads_for_pattern(None, None, None, Some(from_graph_name.into()))
                 .map(|q| Ok(q?.into())),
             writer,
             format,
@@ -601,15 +601,15 @@ impl SledTransaction<'_> {
     ///
     /// Errors related to parameter validation like the base IRI use the `INVALID_INPUT` error kind.
     /// Errors related to a bad syntax in the loaded file use the `INVALID_DATA` error kind.
-    pub fn load_graph(
+    pub fn load_graph<'a>(
         &self,
         reader: impl BufRead,
         format: GraphFormat,
-        to_graph_name: &GraphName,
+        to_graph_name: impl Into<GraphNameRef<'a>>,
         base_iri: Option<&str>,
     ) -> Result<(), SledUnabortableTransactionError> {
         let mut this = self;
-        load_graph(&mut this, reader, format, to_graph_name, base_iri)?;
+        load_graph(&mut this, reader, format, to_graph_name.into(), base_iri)?;
         Ok(())
     }
 
@@ -635,16 +635,22 @@ impl SledTransaction<'_> {
     }
 
     /// Adds a quad to this store during the transaction.
-    pub fn insert(&self, quad: &Quad) -> Result<(), SledUnabortableTransactionError> {
+    pub fn insert<'a>(
+        &self,
+        quad: impl Into<QuadRef<'a>>,
+    ) -> Result<(), SledUnabortableTransactionError> {
         let mut this = self;
-        let quad = this.encode_quad(quad)?;
+        let quad = this.encode_quad(quad.into())?;
         this.insert_encoded(&quad)
     }
 
     /// Removes a quad from this store during the transaction.
-    pub fn remove(&self, quad: &Quad) -> Result<(), SledUnabortableTransactionError> {
+    pub fn remove<'a>(
+        &self,
+        quad: impl Into<QuadRef<'a>>,
+    ) -> Result<(), SledUnabortableTransactionError> {
         let mut this = self;
-        if let Some(quad) = this.get_encoded_quad(quad)? {
+        if let Some(quad) = this.get_encoded_quad(quad.into())? {
             this.remove_encoded(&quad)
         } else {
             Ok(())
@@ -1080,29 +1086,34 @@ fn store() -> Result<(), io::Error> {
     );
     assert_eq!(
         store
-            .quads_for_pattern(Some(&main_s), None, None, None)
+            .quads_for_pattern(Some(main_s.as_ref()), None, None, None)
             .collect::<Result<Vec<_>, _>>()?,
         all_o
     );
     assert_eq!(
         store
-            .quads_for_pattern(Some(&main_s), Some(&main_p), None, None)
+            .quads_for_pattern(Some(main_s.as_ref()), Some(main_p.as_ref()), None, None)
             .collect::<Result<Vec<_>, _>>()?,
         all_o
     );
     assert_eq!(
         store
-            .quads_for_pattern(Some(&main_s), Some(&main_p), Some(&main_o), None)
+            .quads_for_pattern(
+                Some(main_s.as_ref()),
+                Some(main_p.as_ref()),
+                Some(main_o.as_ref()),
+                None
+            )
             .collect::<Result<Vec<_>, _>>()?,
         target
     );
     assert_eq!(
         store
             .quads_for_pattern(
-                Some(&main_s),
-                Some(&main_p),
-                Some(&main_o),
-                Some(&GraphName::DefaultGraph)
+                Some(main_s.as_ref()),
+                Some(main_p.as_ref()),
+                Some(main_o.as_ref()),
+                Some(GraphNameRef::DefaultGraph)
             )
             .collect::<Result<Vec<_>, _>>()?,
         target
@@ -1110,58 +1121,63 @@ fn store() -> Result<(), io::Error> {
     assert_eq!(
         store
             .quads_for_pattern(
-                Some(&main_s),
-                Some(&main_p),
+                Some(main_s.as_ref()),
+                Some(main_p.as_ref()),
                 None,
-                Some(&GraphName::DefaultGraph)
+                Some(GraphNameRef::DefaultGraph)
             )
             .collect::<Result<Vec<_>, _>>()?,
         all_o
     );
     assert_eq!(
         store
-            .quads_for_pattern(Some(&main_s), None, Some(&main_o), None)
+            .quads_for_pattern(Some(main_s.as_ref()), None, Some(main_o.as_ref()), None)
             .collect::<Result<Vec<_>, _>>()?,
         target
     );
     assert_eq!(
         store
             .quads_for_pattern(
-                Some(&main_s),
+                Some(main_s.as_ref()),
                 None,
-                Some(&main_o),
-                Some(&GraphName::DefaultGraph)
+                Some(main_o.as_ref()),
+                Some(GraphNameRef::DefaultGraph)
             )
             .collect::<Result<Vec<_>, _>>()?,
         target
     );
     assert_eq!(
         store
-            .quads_for_pattern(Some(&main_s), None, None, Some(&GraphName::DefaultGraph))
+            .quads_for_pattern(
+                Some(main_s.as_ref()),
+                None,
+                None,
+                Some(GraphNameRef::DefaultGraph)
+            )
             .collect::<Result<Vec<_>, _>>()?,
         all_o
     );
     assert_eq!(
         store
-            .quads_for_pattern(None, Some(&main_p), None, None)
+            .quads_for_pattern(None, Some(main_p.as_ref()), None, None)
             .collect::<Result<Vec<_>, _>>()?,
         all_o
     );
     assert_eq!(
         store
-            .quads_for_pattern(None, Some(&main_p), Some(&main_o), None)
+            .quads_for_pattern(None, Some(main_p.as_ref()), Some(main_o.as_ref()), None)
             .collect::<Result<Vec<_>, _>>()?,
         target
     );
     assert_eq!(
         store
-            .quads_for_pattern(None, None, Some(&main_o), None)
+            .quads_for_pattern(None, None, Some(main_o.as_ref()), None)
             .collect::<Result<Vec<_>, _>>()?,
         target
     );
     assert_eq!(
         store
-            .quads_for_pattern(None, None, None, Some(&GraphName::DefaultGraph))
+            .quads_for_pattern(None, None, None, Some(GraphNameRef::DefaultGraph))
             .collect::<Result<Vec<_>, _>>()?,
         all_o
     );
@@ -1169,9 +1185,9 @@ fn store() -> Result<(), io::Error> {
         store
             .quads_for_pattern(
                 None,
-                Some(&main_p),
-                Some(&main_o),
-                Some(&GraphName::DefaultGraph)
+                Some(main_p.as_ref()),
+                Some(main_o.as_ref()),
+                Some(GraphNameRef::DefaultGraph)
             )
             .collect::<Result<Vec<_>, _>>()?,
         target
diff --git a/python/src/memory_store.rs b/python/src/memory_store.rs
index 7cd2d434..ff4a36fb 100644
--- a/python/src/memory_store.rs
+++ b/python/src/memory_store.rs
@@ -47,10 +47,10 @@ impl PyMemoryStore {
             extract_quads_pattern(subject, predicate, object, graph_name)?;
         Ok(QuadIter {
             inner: Box::new(self.inner.quads_for_pattern(
-                subject.as_ref(),
-                predicate.as_ref(),
-                object.as_ref(),
-                graph_name.as_ref(),
+                subject.as_ref().map(|t| t.into()),
+                predicate.as_ref().map(|t| t.into()),
+                object.as_ref().map(|t| t.into()),
+                graph_name.as_ref().map(|t| t.into()),
             )),
         })
     }
diff --git a/python/src/model.rs b/python/src/model.rs
index 745b7506..237fe4ee 100644
--- a/python/src/model.rs
+++ b/python/src/model.rs
@@ -214,7 +214,7 @@ impl PyLiteral {
 
     #[getter]
     fn datatype(&self) -> PyNamedNode {
-        self.inner.datatype().clone().into()
+        self.inner.datatype().into_owned().into()
     }
 }
 
diff --git a/python/src/sled_store.rs b/python/src/sled_store.rs
index 940fea9c..60882ee0 100644
--- a/python/src/sled_store.rs
+++ b/python/src/sled_store.rs
@@ -49,10 +49,10 @@ impl PySledStore {
             extract_quads_pattern(subject, predicate, object, graph_name)?;
         Ok(QuadIter {
             inner: Box::new(self.inner.quads_for_pattern(
-                subject.as_ref(),
-                predicate.as_ref(),
-                object.as_ref(),
-                graph_name.as_ref(),
+                subject.as_ref().map(|t| t.into()),
+                predicate.as_ref().map(|t| t.into()),
+                object.as_ref().map(|t| t.into()),
+                graph_name.as_ref().map(|t| t.into()),
             )),
         })
     }
diff --git a/testsuite/Cargo.toml b/testsuite/Cargo.toml
index 1985076f..faef551a 100644
--- a/testsuite/Cargo.toml
+++ b/testsuite/Cargo.toml
@@ -14,7 +14,6 @@ publish = false
 [dependencies]
 anyhow = "1"
 chrono = "0.4"
-lazy_static = "1"
 oxigraph = { path = "../lib" }
 
 [dev-dependencies]
diff --git a/testsuite/src/manifest.rs b/testsuite/src/manifest.rs
index 312c65d2..d038ed59 100644
--- a/testsuite/src/manifest.rs
+++ b/testsuite/src/manifest.rs
@@ -72,57 +72,50 @@ impl Iterator for TestManifest {
     fn next(&mut self) -> Option<Result<Test>> {
         match self.tests_to_do.pop() {
             Some(Term::NamedNode(test_node)) => {
-                let test_subject = NamedOrBlankNode::from(test_node.clone());
-                let kind =
-                    match object_for_subject_predicate(&self.graph, &test_subject, &rdf::TYPE) {
-                        Some(Term::NamedNode(c)) => c,
-                        _ => return self.next(), //We ignore the test
-                    };
-                let name = match object_for_subject_predicate(&self.graph, &test_subject, &mf::NAME)
-                {
-                    Some(Term::Literal(c)) => Some(c.value().to_string()),
-                    _ => None,
+                let kind = match object_for_subject_predicate(&self.graph, &test_node, rdf::TYPE) {
+                    Some(Term::NamedNode(c)) => c,
+                    _ => return self.next(), //We ignore the test
                 };
-                let comment = match object_for_subject_predicate(
-                    &self.graph,
-                    &test_subject,
-                    &rdfs::COMMENT,
-                ) {
+                let name = match object_for_subject_predicate(&self.graph, &test_node, mf::NAME) {
                     Some(Term::Literal(c)) => Some(c.value().to_string()),
                     _ => None,
                 };
+                let comment =
+                    match object_for_subject_predicate(&self.graph, &test_node, rdfs::COMMENT) {
+                        Some(Term::Literal(c)) => Some(c.value().to_string()),
+                        _ => None,
+                    };
                 let (action, query, data, graph_data, service_data) =
-                    match object_for_subject_predicate(&self.graph, &test_subject, &*mf::ACTION) {
+                    match object_for_subject_predicate(&self.graph, &test_node, mf::ACTION) {
                         Some(Term::NamedNode(n)) => {
                             (Some(n.into_string()), None, None, vec![], vec![])
                         }
                         Some(Term::BlankNode(n)) => {
-                            let n = n.into();
                             let query =
-                                match object_for_subject_predicate(&self.graph, &n, &qt::QUERY) {
-                                    Some(Term::NamedNode(q)) => Some(q.into_string()),
-                                    _ => None,
-                                };
-                            let data =
-                                match object_for_subject_predicate(&self.graph, &n, &qt::DATA) {
+                                match object_for_subject_predicate(&self.graph, &n, qt::QUERY) {
                                     Some(Term::NamedNode(q)) => Some(q.into_string()),
                                     _ => None,
                                 };
+                            let data = match object_for_subject_predicate(&self.graph, &n, qt::DATA)
+                            {
+                                Some(Term::NamedNode(q)) => Some(q.into_string()),
+                                _ => None,
+                            };
                             let graph_data =
-                                objects_for_subject_predicate(&self.graph, &n, &qt::GRAPH_DATA)
+                                objects_for_subject_predicate(&self.graph, &n, qt::GRAPH_DATA)
                                     .filter_map(|g| match g {
                                         Term::NamedNode(q) => Some(q.into_string()),
                                         _ => None,
                                     })
                                     .collect();
                             let service_data =
-                                objects_for_subject_predicate(&self.graph, &n, &qt::SERVICE_DATA)
+                                objects_for_subject_predicate(&self.graph, &n, qt::SERVICE_DATA)
                                     .filter_map(|g| match g {
                                         Term::NamedNode(g) => Some(g.into()),
                                         Term::BlankNode(g) => Some(g.into()),
                                         _ => None,
                                     })
-                                    .filter_map(|g| {
+                                    .filter_map(|g: NamedOrBlankNode| {
                                         if let (
                                             Some(Term::NamedNode(endpoint)),
                                             Some(Term::NamedNode(data)),
@@ -130,13 +123,9 @@ impl Iterator for TestManifest {
                                             object_for_subject_predicate(
                                                 &self.graph,
                                                 &g,
-                                                &qt::ENDPOINT,
-                                            ),
-                                            object_for_subject_predicate(
-                                                &self.graph,
-                                                &g,
-                                                &qt::DATA,
+                                                qt::ENDPOINT,
                                             ),
+                                            object_for_subject_predicate(&self.graph, &g, qt::DATA),
                                         ) {
                                             Some((endpoint.into_string(), data.into_string()))
                                         } else {
@@ -148,18 +137,15 @@ impl Iterator for TestManifest {
                         }
                         Some(_) => return Some(Err(anyhow!("invalid action"))),
                         None => {
-                            return Some(Err(anyhow!(
-                                "action not found for test {}",
-                                test_subject
-                            )));
+                            return Some(Err(anyhow!("action not found for test {}", test_node)));
                         }
                     };
-                let result =
-                    match object_for_subject_predicate(&self.graph, &test_subject, &*mf::RESULT) {
-                        Some(Term::NamedNode(n)) => Some(n.into_string()),
-                        Some(_) => return Some(Err(anyhow!("invalid result"))),
-                        None => None,
-                    };
+                let result = match object_for_subject_predicate(&self.graph, &test_node, mf::RESULT)
+                {
+                    Some(Term::NamedNode(n)) => Some(n.into_string()),
+                    Some(_) => return Some(Err(anyhow!("invalid result"))),
+                    None => None,
+                };
                 Some(Ok(Test {
                     id: test_node,
                     kind,
@@ -177,7 +163,8 @@ impl Iterator for TestManifest {
             None => {
                 match self.manifests_to_do.pop() {
                     Some(url) => {
-                        let manifest = NamedOrBlankNode::from(NamedNode::new(url.clone()).unwrap());
+                        let manifest =
+                            NamedOrBlankNodeRef::from(NamedNodeRef::new(url.as_str()).unwrap());
                         if let Err(error) =
                             load_to_store(&url, &self.graph, &&GraphName::DefaultGraph)
                         {
@@ -185,7 +172,7 @@ impl Iterator for TestManifest {
                         }
 
                         // New manifests
-                        match object_for_subject_predicate(&self.graph, &manifest, &*mf::INCLUDE) {
+                        match object_for_subject_predicate(&self.graph, manifest, mf::INCLUDE) {
                             Some(Term::BlankNode(list)) => {
                                 self.manifests_to_do.extend(
                                     RdfListIterator::iter(&self.graph, list.into()).filter_map(
@@ -201,7 +188,7 @@ impl Iterator for TestManifest {
                         }
 
                         // New tests
-                        match object_for_subject_predicate(&self.graph, &manifest, &*mf::ENTRIES) {
+                        match object_for_subject_predicate(&self.graph, manifest, mf::ENTRIES) {
                             Some(Term::BlankNode(list)) => {
                                 self.tests_to_do
                                     .extend(RdfListIterator::iter(&self.graph, list.into()));
@@ -240,10 +227,10 @@ impl<'a> Iterator for RdfListIterator<'a> {
     fn next(&mut self) -> Option<Term> {
         match self.current_node.clone() {
             Some(current) => {
-                let result = object_for_subject_predicate(&self.graph, &current, &rdf::FIRST);
+                let result = object_for_subject_predicate(&self.graph, &current, rdf::FIRST);
                 self.current_node =
-                    match object_for_subject_predicate(&self.graph, &current, &rdf::REST) {
-                        Some(Term::NamedNode(ref n)) if *n == *rdf::NIL => None,
+                    match object_for_subject_predicate(&self.graph, &current, rdf::REST) {
+                        Some(Term::NamedNode(n)) if n == rdf::NIL => None,
                         Some(Term::NamedNode(n)) => Some(n.into()),
                         Some(Term::BlankNode(n)) => Some(n.into()),
                         _ => None,
@@ -255,20 +242,20 @@ impl<'a> Iterator for RdfListIterator<'a> {
     }
 }
 
-fn object_for_subject_predicate(
+fn object_for_subject_predicate<'a>(
     store: &MemoryStore,
-    subject: &NamedOrBlankNode,
-    predicate: &NamedNode,
+    subject: impl Into<NamedOrBlankNodeRef<'a>>,
+    predicate: impl Into<NamedNodeRef<'a>>,
 ) -> Option<Term> {
     objects_for_subject_predicate(store, subject, predicate).next()
 }
 
-fn objects_for_subject_predicate(
+fn objects_for_subject_predicate<'a>(
     store: &MemoryStore,
-    subject: &NamedOrBlankNode,
-    predicate: &NamedNode,
+    subject: impl Into<NamedOrBlankNodeRef<'a>>,
+    predicate: impl Into<NamedNodeRef<'a>>,
 ) -> impl Iterator<Item = Term> {
     store
-        .quads_for_pattern(Some(subject), Some(predicate), None, None)
+        .quads_for_pattern(Some(subject.into()), Some(predicate.into()), None, None)
         .map(|t| t.object)
 }
diff --git a/testsuite/src/sparql_evaluator.rs b/testsuite/src/sparql_evaluator.rs
index cf37e461..586d9ae6 100644
--- a/testsuite/src/sparql_evaluator.rs
+++ b/testsuite/src/sparql_evaluator.rs
@@ -200,13 +200,13 @@ fn to_dataset(result: QueryResult, with_order: bool) -> Result<MemoryStore> {
             let result_set = BlankNode::default();
             store.insert(Quad::new(
                 result_set.clone(),
-                rdf::TYPE.clone(),
-                rs::RESULT_SET.clone(),
+                rdf::TYPE,
+                rs::RESULT_SET,
                 None,
             ));
             store.insert(Quad::new(
                 result_set,
-                rs::BOOLEAN.clone(),
+                rs::BOOLEAN,
                 Literal::from(value),
                 None,
             ));
@@ -217,14 +217,14 @@ fn to_dataset(result: QueryResult, with_order: bool) -> Result<MemoryStore> {
             let result_set = BlankNode::default();
             store.insert(Quad::new(
                 result_set.clone(),
-                rdf::TYPE.clone(),
-                rs::RESULT_SET.clone(),
+                rdf::TYPE,
+                rs::RESULT_SET,
                 None,
             ));
             for variable in solutions.variables() {
                 store.insert(Quad::new(
                     result_set.clone(),
-                    rs::RESULT_VARIABLE.clone(),
+                    rs::RESULT_VARIABLE,
                     Literal::new_simple_literal(variable.as_str()),
                     None,
                 ));
@@ -234,7 +234,7 @@ fn to_dataset(result: QueryResult, with_order: bool) -> Result<MemoryStore> {
                 let solution_id = BlankNode::default();
                 store.insert(Quad::new(
                     result_set.clone(),
-                    rs::SOLUTION.clone(),
+                    rs::SOLUTION,
                     solution_id.clone(),
                     None,
                 ));
@@ -242,19 +242,14 @@ fn to_dataset(result: QueryResult, with_order: bool) -> Result<MemoryStore> {
                     let binding = BlankNode::default();
                     store.insert(Quad::new(
                         solution_id.clone(),
-                        rs::BINDING.clone(),
+                        rs::BINDING,
                         binding.clone(),
                         None,
                     ));
-                    store.insert(Quad::new(
-                        binding.clone(),
-                        rs::VALUE.clone(),
-                        value.clone(),
-                        None,
-                    ));
+                    store.insert(Quad::new(binding.clone(), rs::VALUE, value.clone(), None));
                     store.insert(Quad::new(
                         binding,
-                        rs::VARIABLE.clone(),
+                        rs::VARIABLE,
                         Literal::new_simple_literal(variable.as_str()),
                         None,
                     ));
@@ -262,7 +257,7 @@ fn to_dataset(result: QueryResult, with_order: bool) -> Result<MemoryStore> {
                 if with_order {
                     store.insert(Quad::new(
                         solution_id,
-                        rs::INDEX.clone(),
+                        rs::INDEX,
                         Literal::from((i + 1) as i128),
                         None,
                     ));
@@ -374,92 +369,75 @@ impl StaticQueryResults {
 
     fn from_dataset(dataset: MemoryStore) -> StaticQueryResults {
         if let Some(result_set) = dataset
-            .quads_for_pattern(
-                None,
-                Some(&rdf::TYPE),
-                Some(&rs::RESULT_SET.clone().into()),
-                None,
-            )
+            .quads_for_pattern(None, Some(rdf::TYPE), Some(rs::RESULT_SET.into()), None)
             .map(|q| q.subject)
             .next()
         {
-            if let Some(bool) = dataset
-                .quads_for_pattern(Some(&result_set), Some(&rs::BOOLEAN), None, None)
-                .map(|q| q.object)
-                .next()
-            {
+            if let Some(bool) = object_for_subject_predicate(&dataset, &result_set, rs::BOOLEAN) {
                 // Boolean query
                 StaticQueryResults::Boolean(bool == Literal::from(true).into())
             } else {
                 // Regular query
-                let mut variables: Vec<Variable> = dataset
-                    .quads_for_pattern(Some(&result_set), Some(&rs::RESULT_VARIABLE), None, None)
-                    .filter_map(|q| {
-                        if let Term::Literal(l) = q.object {
-                            Some(Variable::new(l.value()))
-                        } else {
-                            None
-                        }
-                    })
-                    .collect();
+                let mut variables: Vec<Variable> =
+                    objects_for_subject_predicate(&dataset, &result_set, rs::RESULT_VARIABLE)
+                        .filter_map(|object| {
+                            if let Term::Literal(l) = object {
+                                Some(Variable::new(l.value()))
+                            } else {
+                                None
+                            }
+                        })
+                        .collect();
                 variables.sort();
 
-                let mut solutions: Vec<_> = dataset
-                    .quads_for_pattern(Some(&result_set), Some(&rs::SOLUTION), None, None)
-                    .filter_map(|q| {
-                        if let Term::BlankNode(solution) = q.object {
-                            let solution = solution.into();
-                            let mut bindings = dataset
-                                .quads_for_pattern(Some(&solution), Some(&rs::BINDING), None, None)
-                                .filter_map(|q| {
-                                    if let Term::BlankNode(binding) = q.object {
-                                        let binding = binding.into();
-                                        if let (Some(Term::Literal(variable)), Some(value)) = (
-                                            dataset
-                                                .quads_for_pattern(
-                                                    Some(&binding),
-                                                    Some(&rs::VARIABLE),
-                                                    None,
-                                                    None,
-                                                )
-                                                .map(|q| q.object)
-                                                .next(),
-                                            dataset
-                                                .quads_for_pattern(
-                                                    Some(&binding),
-                                                    Some(&rs::VALUE),
-                                                    None,
-                                                    None,
-                                                )
-                                                .map(|q| q.object)
-                                                .next(),
-                                        ) {
-                                            Some((Variable::new(variable.value()), value))
-                                        } else {
-                                            None
-                                        }
-                                    } else {
-                                        None
-                                    }
-                                })
-                                .collect::<Vec<_>>();
-                            bindings.sort_by(|(a, _), (b, _)| a.cmp(&b));
-                            let index = dataset
-                                .quads_for_pattern(Some(&solution), Some(&rs::INDEX), None, None)
-                                .filter_map(|q| {
-                                    if let Term::Literal(l) = q.object {
-                                        u64::from_str(l.value()).ok()
-                                    } else {
-                                        None
-                                    }
-                                })
-                                .next();
-                            Some((bindings, index))
-                        } else {
-                            None
-                        }
-                    })
-                    .collect();
+                let mut solutions: Vec<_> =
+                    objects_for_subject_predicate(&dataset, &result_set, rs::SOLUTION)
+                        .filter_map(|object| {
+                            if let Term::BlankNode(solution) = object {
+                                let mut bindings =
+                                    objects_for_subject_predicate(&dataset, &solution, rs::BINDING)
+                                        .filter_map(|object| {
+                                            if let Term::BlankNode(binding) = object {
+                                                if let (
+                                                    Some(Term::Literal(variable)),
+                                                    Some(value),
+                                                ) = (
+                                                    object_for_subject_predicate(
+                                                        &dataset,
+                                                        &binding,
+                                                        rs::VARIABLE,
+                                                    ),
+                                                    object_for_subject_predicate(
+                                                        &dataset,
+                                                        &binding,
+                                                        rs::VALUE,
+                                                    ),
+                                                ) {
+                                                    Some((Variable::new(variable.value()), value))
+                                                } else {
+                                                    None
+                                                }
+                                            } else {
+                                                None
+                                            }
+                                        })
+                                        .collect::<Vec<_>>();
+                                bindings.sort_by(|(a, _), (b, _)| a.cmp(&b));
+                                let index =
+                                    object_for_subject_predicate(&dataset, &solution, rs::INDEX)
+                                        .and_then(|object| {
+                                            if let Term::Literal(l) = object {
+                                                u64::from_str(l.value()).ok()
+                                            } else {
+                                                None
+                                            }
+                                        });
+                                Some((bindings, index))
+                            } else {
+                                None
+                            }
+                        })
+                        .collect();
                 solutions.sort_by(|(_, index_a), (_, index_b)| index_a.cmp(index_b));
 
                 let ordered = solutions.iter().all(|(_, index)| index.is_some());
@@ -478,3 +456,21 @@ impl StaticQueryResults {
         }
     }
 }
+
+fn object_for_subject_predicate<'a>(
+    store: &MemoryStore,
+    subject: impl Into<NamedOrBlankNodeRef<'a>>,
+    predicate: impl Into<NamedNodeRef<'a>>,
+) -> Option<Term> {
+    objects_for_subject_predicate(store, subject, predicate).next()
+}
+
+fn objects_for_subject_predicate<'a>(
+    store: &MemoryStore,
+    subject: impl Into<NamedOrBlankNodeRef<'a>>,
+    predicate: impl Into<NamedNodeRef<'a>>,
+) -> impl Iterator<Item = Term> {
+    store
+        .quads_for_pattern(Some(subject.into()), Some(predicate.into()), None, None)
+        .map(|t| t.object)
+}
diff --git a/testsuite/src/vocab.rs b/testsuite/src/vocab.rs
index 97e0797e..9f3a4e92 100644
--- a/testsuite/src/vocab.rs
+++ b/testsuite/src/vocab.rs
@@ -1,73 +1,64 @@
 pub mod rs {
-    use lazy_static::lazy_static;
-    use oxigraph::model::NamedNode;
+    use oxigraph::model::NamedNodeRef;
 
-    lazy_static! {
-        pub static ref RESULT_SET: NamedNode =
-            NamedNode::new("http://www.w3.org/2001/sw/DataAccess/tests/result-set#ResultSet")
-                .unwrap();
-        pub static ref RESULT_VARIABLE: NamedNode =
-            NamedNode::new("http://www.w3.org/2001/sw/DataAccess/tests/result-set#resultVariable")
-                .unwrap();
-        pub static ref SOLUTION: NamedNode =
-            NamedNode::new("http://www.w3.org/2001/sw/DataAccess/tests/result-set#solution")
-                .unwrap();
-        pub static ref BINDING: NamedNode =
-            NamedNode::new("http://www.w3.org/2001/sw/DataAccess/tests/result-set#binding")
-                .unwrap();
-        pub static ref VALUE: NamedNode =
-            NamedNode::new("http://www.w3.org/2001/sw/DataAccess/tests/result-set#value").unwrap();
-        pub static ref VARIABLE: NamedNode =
-            NamedNode::new("http://www.w3.org/2001/sw/DataAccess/tests/result-set#variable")
-                .unwrap();
-        pub static ref INDEX: NamedNode =
-            NamedNode::new("http://www.w3.org/2001/sw/DataAccess/tests/result-set#index").unwrap();
-        pub static ref BOOLEAN: NamedNode =
-            NamedNode::new("http://www.w3.org/2001/sw/DataAccess/tests/result-set#boolean")
-                .unwrap();
-    }
+    pub const RESULT_SET: NamedNodeRef<'_> = NamedNodeRef::new_unchecked(
+        "http://www.w3.org/2001/sw/DataAccess/tests/result-set#ResultSet",
+    );
+    pub const RESULT_VARIABLE: NamedNodeRef<'_> = NamedNodeRef::new_unchecked(
+        "http://www.w3.org/2001/sw/DataAccess/tests/result-set#resultVariable",
+    );
+    pub const SOLUTION: NamedNodeRef<'_> = NamedNodeRef::new_unchecked(
+        "http://www.w3.org/2001/sw/DataAccess/tests/result-set#solution",
+    );
+    pub const BINDING: NamedNodeRef<'_> = NamedNodeRef::new_unchecked(
+        "http://www.w3.org/2001/sw/DataAccess/tests/result-set#binding",
+    );
+    pub const VALUE: NamedNodeRef<'_> =
+        NamedNodeRef::new_unchecked("http://www.w3.org/2001/sw/DataAccess/tests/result-set#value");
+    pub const VARIABLE: NamedNodeRef<'_> = NamedNodeRef::new_unchecked(
+        "http://www.w3.org/2001/sw/DataAccess/tests/result-set#variable",
+    );
+    pub const INDEX: NamedNodeRef<'_> =
+        NamedNodeRef::new_unchecked("http://www.w3.org/2001/sw/DataAccess/tests/result-set#index");
+    pub const BOOLEAN: NamedNodeRef<'_> = NamedNodeRef::new_unchecked(
+        "http://www.w3.org/2001/sw/DataAccess/tests/result-set#boolean",
+    );
 }
 
 pub mod mf {
-    use lazy_static::lazy_static;
-    use oxigraph::model::NamedNode;
+    use oxigraph::model::NamedNodeRef;
 
-    lazy_static! {
-        pub static ref INCLUDE: NamedNode =
-            NamedNode::new("http://www.w3.org/2001/sw/DataAccess/tests/test-manifest#include")
-                .unwrap();
-        pub static ref ENTRIES: NamedNode =
-            NamedNode::new("http://www.w3.org/2001/sw/DataAccess/tests/test-manifest#entries")
-                .unwrap();
-        pub static ref NAME: NamedNode =
-            NamedNode::new("http://www.w3.org/2001/sw/DataAccess/tests/test-manifest#name")
-                .unwrap();
-        pub static ref ACTION: NamedNode =
-            NamedNode::new("http://www.w3.org/2001/sw/DataAccess/tests/test-manifest#action")
-                .unwrap();
-        pub static ref RESULT: NamedNode =
-            NamedNode::new("http://www.w3.org/2001/sw/DataAccess/tests/test-manifest#result")
-                .unwrap();
-    }
+    pub const INCLUDE: NamedNodeRef<'_> = NamedNodeRef::new_unchecked(
+        "http://www.w3.org/2001/sw/DataAccess/tests/test-manifest#include",
+    );
+    pub const ENTRIES: NamedNodeRef<'_> = NamedNodeRef::new_unchecked(
+        "http://www.w3.org/2001/sw/DataAccess/tests/test-manifest#entries",
+    );
+    pub const NAME: NamedNodeRef<'_> = NamedNodeRef::new_unchecked(
+        "http://www.w3.org/2001/sw/DataAccess/tests/test-manifest#name",
+    );
+    pub const ACTION: NamedNodeRef<'_> = NamedNodeRef::new_unchecked(
+        "http://www.w3.org/2001/sw/DataAccess/tests/test-manifest#action",
+    );
+    pub const RESULT: NamedNodeRef<'_> = NamedNodeRef::new_unchecked(
+        "http://www.w3.org/2001/sw/DataAccess/tests/test-manifest#result",
+    );
 }
 
 pub mod qt {
-    use lazy_static::lazy_static;
-    use oxigraph::model::NamedNode;
+    use oxigraph::model::NamedNodeRef;
 
-    lazy_static! {
-        pub static ref QUERY: NamedNode =
-            NamedNode::new("http://www.w3.org/2001/sw/DataAccess/tests/test-query#query").unwrap();
-        pub static ref DATA: NamedNode =
-            NamedNode::new("http://www.w3.org/2001/sw/DataAccess/tests/test-query#data").unwrap();
-        pub static ref GRAPH_DATA: NamedNode =
-            NamedNode::new("http://www.w3.org/2001/sw/DataAccess/tests/test-query#graphData")
-                .unwrap();
-        pub static ref SERVICE_DATA: NamedNode =
-            NamedNode::new("http://www.w3.org/2001/sw/DataAccess/tests/test-query#serviceData")
-                .unwrap();
-        pub static ref ENDPOINT: NamedNode =
-            NamedNode::new("http://www.w3.org/2001/sw/DataAccess/tests/test-query#endpoint")
-                .unwrap();
-    }
+    pub const QUERY: NamedNodeRef<'_> =
+        NamedNodeRef::new_unchecked("http://www.w3.org/2001/sw/DataAccess/tests/test-query#query");
+    pub const DATA: NamedNodeRef<'_> =
+        NamedNodeRef::new_unchecked("http://www.w3.org/2001/sw/DataAccess/tests/test-query#data");
+    pub const GRAPH_DATA: NamedNodeRef<'_> = NamedNodeRef::new_unchecked(
+        "http://www.w3.org/2001/sw/DataAccess/tests/test-query#graphData",
+    );
+    pub const SERVICE_DATA: NamedNodeRef<'_> = NamedNodeRef::new_unchecked(
+        "http://www.w3.org/2001/sw/DataAccess/tests/test-query#serviceData",
+    );
+    pub const ENDPOINT: NamedNodeRef<'_> = NamedNodeRef::new_unchecked(
+        "http://www.w3.org/2001/sw/DataAccess/tests/test-query#endpoint",
+    );
 }
diff --git a/wikibase/src/loader.rs b/wikibase/src/loader.rs
index f17d7587..393ccda3 100644
--- a/wikibase/src/loader.rs
+++ b/wikibase/src/loader.rs
@@ -6,7 +6,7 @@ use http_client::h1::H1Client;
 use http_client::HttpClient;
 use http_types::{headers, Method, Request, Result};
 use oxigraph::io::GraphFormat;
-use oxigraph::model::NamedNode;
+use oxigraph::model::NamedNodeRef;
 use oxigraph::RocksDbStore;
 use serde_json::Value;
 use std::collections::{HashMap, HashSet};
@@ -230,11 +230,11 @@ impl WikibaseLoader {
     }
 
     fn load_entity_data(&self, uri: &str, data: impl Read) -> Result<()> {
-        let graph_name = NamedNode::new(uri)?.into();
+        let graph_name = NamedNodeRef::new(uri)?.into();
         self.store.transaction(|transaction| {
             let to_remove = self
                 .store
-                .quads_for_pattern(None, None, None, Some(&graph_name))
+                .quads_for_pattern(None, None, None, Some(graph_name))
                 .collect::<std::result::Result<Vec<_>, _>>()?;
             for q in to_remove {
                 transaction.remove(&q)?;
@@ -243,7 +243,7 @@ impl WikibaseLoader {
             transaction.load_graph(
                 BufReader::new(data),
                 GraphFormat::NTriples,
-                &NamedNode::new(uri)?.into(),
+                NamedNodeRef::new(uri)?,
                 None,
             )?;
             Ok(())