RocksDB: Adds prefix bloom filters

lib/src/storage/fallback_backend.rs

@@ -11,6 +11,8 @@ pub struct ColumnFamilyDefinition {
     pub name: &'static str,
     pub merge_operator: Option<MergeOperator>,
     pub compaction_filter: Option<CompactionFilter>,
+    pub use_iter: bool,
+    pub min_prefix_size: usize,
 }
 
 #[derive(Clone)]

lib/src/storage/mod.rs

@@ -78,66 +78,77 @@ impl Storage {
                 merge_operator: Some(Self::str2id_merge()),
                 compaction_filter: Some(Self::str2id_filter()),
                 use_iter: false,
+                min_prefix_size: 0,
             },
             ColumnFamilyDefinition {
                 name: SPOG_CF,
                 merge_operator: None,
                 compaction_filter: None,
                 use_iter: true,
+                min_prefix_size: 17, // named or blank node start
             },
             ColumnFamilyDefinition {
                 name: POSG_CF,
                 merge_operator: None,
                 compaction_filter: None,
                 use_iter: true,
+                min_prefix_size: 17, // named node start
             },
             ColumnFamilyDefinition {
                 name: OSPG_CF,
                 merge_operator: None,
                 compaction_filter: None,
                 use_iter: true,
+                min_prefix_size: 0, // There are small literals...
             },
             ColumnFamilyDefinition {
                 name: GSPO_CF,
                 merge_operator: None,
                 compaction_filter: None,
                 use_iter: true,
+                min_prefix_size: 17, // named or blank node start
             },
             ColumnFamilyDefinition {
                 name: GPOS_CF,
                 merge_operator: None,
                 compaction_filter: None,
                 use_iter: true,
+                min_prefix_size: 17, // named or blank node start
             },
             ColumnFamilyDefinition {
                 name: GOSP_CF,
                 merge_operator: None,
                 compaction_filter: None,
                 use_iter: true,
+                min_prefix_size: 17, // named or blank node start
             },
             ColumnFamilyDefinition {
                 name: DSPO_CF,
                 merge_operator: None,
                 compaction_filter: None,
                 use_iter: true,
+                min_prefix_size: 17, // named or blank node start
             },
             ColumnFamilyDefinition {
                 name: DPOS_CF,
                 merge_operator: None,
                 compaction_filter: None,
                 use_iter: true,
+                min_prefix_size: 17, // named or blank node start
             },
             ColumnFamilyDefinition {
                 name: DOSP_CF,
                 merge_operator: None,
                 compaction_filter: None,
                 use_iter: true,
+                min_prefix_size: 0, // There are small literals...
             },
             ColumnFamilyDefinition {
                 name: GRAPHS_CF,
                 merge_operator: None,
                 compaction_filter: None,
                 use_iter: true,
+                min_prefix_size: 17, // named or blank node start
             },
         ]
     }

lib/src/storage/rocksdb_backend.rs

@@ -45,6 +45,7 @@ pub struct ColumnFamilyDefinition {
     pub merge_operator: Option<MergeOperator>,
     pub compaction_filter: Option<CompactionFilter>,
     pub use_iter: bool,
+    pub min_prefix_size: usize,
 }
 
 #[derive(Clone)]
@@ -169,6 +170,7 @@ impl Db {
                     merge_operator: None,
                     compaction_filter: None,
                     use_iter: true,
+                    min_prefix_size: 0,
                 })
             }
             let column_family_names = column_families.iter().map(|c| c.name).collect::<Vec<_>>();
@@ -185,6 +187,12 @@ impl Db {
                     if !cf.use_iter {
                         rocksdb_options_optimize_for_point_lookup(options, 128);
                     }
+                    if cf.min_prefix_size > 0 {
+                        rocksdb_options_set_prefix_extractor(
+                            options,
+                            rocksdb_slicetransform_create_fixed_prefix(cf.min_prefix_size),
+                        );
+                    }
                     if let Some(merge) = cf.merge_operator {
                         // mergeoperator delete is done automatically
                         let merge = rocksdb_mergeoperator_create(