diff --git a/src/ffi.rs b/src/ffi.rs
index d727556..dfca528 100644
--- a/src/ffi.rs
+++ b/src/ffi.rs
@@ -112,26 +112,28 @@ extern {
         options: RocksDBOptions, path: *const i8, err: *mut i8);
     pub fn rocksdb_repair_db(
         options: RocksDBOptions, path: *const i8, err: *mut i8);
-
-    // Merge Operator
+    // Merge
+    pub fn rocksdb_merge(db: RocksDBInstance, writeopts: RocksDBWriteOptions,
+        k: *const u8, kLen: size_t,
+        v: *const u8, vLen: size_t, err: *mut i8);
     pub fn rocksdb_mergeoperator_create(
         state: *mut c_void,
         destroy: extern fn(*mut c_void) -> (),
         full_merge: extern fn (
-            arg: *mut c_void, key: *const c_char, key_len: *mut size_t,
-            existing_value: *const c_char, existing_value_len: *mut size_t,
-            operands_list: &[*const c_char], operands_list_len: *const size_t,
+            arg: *mut c_void, key: *const c_char, key_len: size_t,
+            existing_value: *const c_char, existing_value_len: size_t,
+            operands_list: *const *const c_char, operands_list_len: *const size_t,
             num_operands: c_int,
             success: *mut u8, new_value_length: *mut size_t
         ) -> *const c_char,
         partial_merge: extern fn(
-            *mut c_void, key: *const c_char, key_len: *mut size_t,
-            operands_list: &[*const c_char], operands_list_len: *const size_t,
+            arg: *mut c_void, key: *const c_char, key_len: size_t,
+            operands_list: *const *const c_char, operands_list_len: *const size_t,
             num_operands: c_int,
             success: *mut u8, new_value_length: *mut size_t
         ) -> *const c_char,
-        delete_value: extern fn(*mut c_void, value: *const c_char,
-            value_len: *mut size_t) -> (),
+        delete_value: Option<extern "C" fn(*mut c_void, value: *const c_char,
+            value_len: *mut size_t) -> ()>,
         name_fn: extern fn(*mut c_void) -> *const c_char,
     ) -> RocksDBMergeOperator;
     pub fn rocksdb_mergeoperator_destroy(mo: RocksDBMergeOperator);
@@ -152,14 +154,13 @@ fn internal() {
         rocksdb_options_optimize_level_style_compaction(opts, 0);
         rocksdb_options_set_create_if_missing(opts, 1);
 
-        let rustpath = "internaltest";
+        let rustpath = "_rust_rocksdb_internaltest";
         let cpath = rustpath.to_c_str();
         let cpath_ptr = cpath.as_ptr();
 
         let err = 0 as *mut i8;
         let db = rocksdb_open(opts, cpath_ptr, err);
         assert!(err.is_null());
-        libc::free(err as *mut c_void);
 
         let writeopts = rocksdb_writeoptions_create();
         let RocksDBWriteOptions(write_opt_ptr) = writeopts;
@@ -170,18 +171,17 @@ fn internal() {
 
         rocksdb_put(db, writeopts, key.as_ptr(), 4, val.as_ptr(), 8, err);
         assert!(err.is_null());
-        libc::free(err as *mut c_void);
 
         let readopts = rocksdb_readoptions_create();
         let RocksDBReadOptions(read_opts_ptr) = readopts;
         assert!(read_opts_ptr.is_not_null());
-        libc::free(err as *mut c_void);
 
         let val_len: size_t = 0;
         let val_len_ptr = &val_len as *const size_t;
         rocksdb_get(db, readopts, key.as_ptr(), 4, val_len_ptr, err);
         assert!(err.is_null());
-        libc::free(err as *mut c_void);
         rocksdb_close(db);
+        rocksdb_destroy_db(opts, cpath_ptr, err);
+        assert!(err.is_null());
     }
 }
diff --git a/src/rocksdb.rs b/src/rocksdb.rs
index fb3006b..b732955 100644
--- a/src/rocksdb.rs
+++ b/src/rocksdb.rs
@@ -1,9 +1,13 @@
 extern crate libc;
-use self::libc::{c_void, size_t};
+use self::libc::{c_char, c_int, c_void, size_t};
 use std::io::{IoError};
 use std::c_vec::CVec;
 use std::c_str::CString;
 use std::str::from_utf8;
+use std::string::raw::from_buf_len;
+use std::ptr;
+use std::mem;
+use std::slice;
 
 use rocksdb_ffi;
 
@@ -50,8 +54,20 @@ impl RocksDBOptions {
         }
     }
 
-    pub fn set_merge_operator(&self, mo: rocksdb_ffi::RocksDBMergeOperator) {
+    pub fn add_merge_operator<'a>(&self, name: &str, merge_fn: for <'a> fn (&[u8], Option<&[u8]>, &mut MergeOperands) -> Vec<u8>) {
+        let cb = box MergeOperatorCallback {
+            name: name.to_c_str(),
+            merge_fn: merge_fn,
+        };
+
         unsafe {
+            let mo = rocksdb_ffi::rocksdb_mergeoperator_create(
+                mem::transmute(cb),
+                destructor_callback,
+                full_merge_callback,
+                partial_merge_callback,
+                None,
+                name_callback);
             rocksdb_ffi::rocksdb_options_set_merge_operator(self.inner, mo);
         }
     }
@@ -94,6 +110,29 @@ impl RocksDB {
             Ok(RocksDB{inner: db})
         }
     }
+    
+    pub fn destroy(opts: RocksDBOptions, path: &str) -> Result<(), String> {
+        unsafe {
+            let cpath = path.to_c_str();
+            let cpath_ptr = cpath.as_ptr();
+
+            //TODO test path here, as if rocksdb fails it will just crash the
+            //     process currently
+
+            let err = 0 as *mut i8;
+            let result = rocksdb_ffi::rocksdb_destroy_db(opts.inner, cpath_ptr, err);
+            if err.is_not_null() {
+                let cs = CString::new(err as *const i8, true);
+                match cs.as_str() {
+                    Some(error_string) =>
+                        return Err(error_string.to_string()),
+                    None =>
+                        return Err("Could not initialize database.".to_string()),
+                }
+            }
+            Ok(())
+        }
+    }
 
     pub fn put(&self, key: &[u8], value: &[u8]) -> Result<(), String> {
         unsafe {
@@ -121,6 +160,33 @@ impl RocksDB {
         }
     }
 
+    pub fn merge(&self, key: &[u8], value: &[u8]) -> Result<(), String> {
+        unsafe {
+            let writeopts = rocksdb_ffi::rocksdb_writeoptions_create();
+            let err = 0 as *mut i8;
+            rocksdb_ffi::rocksdb_merge(self.inner, writeopts, key.as_ptr(),
+                        key.len() as size_t, value.as_ptr(),
+                        value.len() as size_t, err);
+            if err.is_not_null() {
+                let cs = CString::new(err as *const i8, true);
+                match cs.as_str() {
+                    Some(error_string) =>
+                        return Err(error_string.to_string()),
+                    None => {
+                        let ie = IoError::last_error();
+                        return Err(format!(
+                                "ERROR: desc:{}, details:{}",
+                                ie.desc,
+                                ie.detail.unwrap_or_else(
+                                    || {"none provided by OS".to_string()})))
+                    }
+                }
+            }
+            return Ok(())
+        }
+    }
+
+
     pub fn get<'a>(&self, key: &[u8]) ->
         RocksDBResult<'a, RocksDBVector, String> {
         unsafe {
@@ -288,7 +354,8 @@ impl <'a,T,E> RocksDBResult<'a,T,E> {
 #[allow(dead_code)]
 #[test]
 fn external() {
-    let db = RocksDB::open_default("externaltest").unwrap();
+    let path = "_rust_rocksdb_externaltest";
+    let db = RocksDB::open_default(path).unwrap();
     let p = db.put(b"k1", b"v1111");
     assert!(p.is_ok());
     let r: RocksDBResult<RocksDBVector, String> = db.get(b"k1");
@@ -296,4 +363,168 @@ fn external() {
     assert!(db.delete(b"k1").is_ok());
     assert!(db.get(b"k1").is_none());
     db.close();
+    let opts = RocksDBOptions::new();
+    assert!(RocksDB::destroy(opts, path).is_ok());
+}
+
+pub struct MergeOperands<'a> {
+    operands_list: *const *const c_char,
+    operands_list_len: *const size_t,
+    num_operands: uint,
+    cursor: uint,
+}
+
+impl <'a> MergeOperands<'a> {
+    fn new<'a>(operands_list: *const *const c_char, operands_list_len: *const size_t,
+        num_operands: c_int) -> MergeOperands<'a> {
+        assert!(num_operands >= 0);
+        MergeOperands {
+            operands_list: operands_list,
+            operands_list_len: operands_list_len,
+            num_operands: num_operands as uint,
+            cursor: 0,
+        }
+    }
+}
+
+impl <'a> Iterator<&'a [u8]> for &'a mut MergeOperands<'a> {
+    fn next(&mut self) -> Option<&'a [u8]> {
+        use std::raw::Slice;
+        match self.cursor == self.num_operands {
+            true => None,
+            false => {
+                unsafe {
+                    let base = self.operands_list as uint;
+                    let base_len = self.operands_list_len as uint;
+                    let spacing = mem::size_of::<*const *const u8>();
+                    let spacing_len = mem::size_of::<*const size_t>();
+                    let len_ptr = (base_len + (spacing_len * self.cursor)) as *const size_t;
+                    let len = *len_ptr as uint;
+                    let ptr = base + (spacing * self.cursor);
+                    let op = from_buf_len(*(ptr as *const *const u8), len);
+                    let des: Option<uint> = from_str(op.as_slice());
+                    self.cursor += 1;
+                    Some(mem::transmute(Slice{data:*(ptr as *const *const u8) as *const u8, len: len}))
+                }
+            }
+        }
+    }
+
+    fn size_hint(&self) -> (uint, Option<uint>) {
+        let remaining = self.num_operands - self.cursor;
+        (remaining, Some(remaining))
+    }
+}
+
+struct MergeOperatorCallback {
+    name: CString,
+    merge_fn: for <'b> fn (&[u8], Option<&[u8]>, &mut MergeOperands) -> Vec<u8>,
+}
+
+extern "C" fn destructor_callback(raw_cb: *mut c_void) {
+    // turn this back into a local variable so rust will reclaim it
+    let _: Box<MergeOperatorCallback> = unsafe {mem::transmute(raw_cb)};
+    
+}
+
+extern "C" fn name_callback(raw_cb: *mut c_void) -> *const c_char {
+    unsafe {
+        let cb: &mut MergeOperatorCallback = &mut *(raw_cb as *mut MergeOperatorCallback);
+        let ptr = cb.name.as_ptr();
+        ptr as *const c_char
+    }
+}
+
+extern "C" fn full_merge_callback(
+    raw_cb: *mut c_void, key: *const c_char, key_len: size_t,
+    existing_value: *const c_char, existing_value_len: size_t,
+    operands_list: *const *const c_char, operands_list_len: *const size_t,
+    num_operands: c_int,
+    success: *mut u8, new_value_length: *mut size_t) -> *const c_char {
+    unsafe {
+        let cb: &mut MergeOperatorCallback = &mut *(raw_cb as *mut MergeOperatorCallback);
+        let operands = &mut MergeOperands::new(operands_list, operands_list_len, num_operands);
+        let key = from_buf_len(key as *const u8, key_len as uint);
+        let oldval = from_buf_len(existing_value as *const u8, existing_value_len as uint);
+        let mut result = (cb.merge_fn)(key.as_bytes(), Some(oldval.as_bytes()), operands);
+        result.shrink_to_fit();
+        //TODO(tan) investigate zero-copy techniques to improve performance
+        let buf = libc::malloc(result.len() as size_t);
+        assert!(buf.is_not_null());
+        *new_value_length = result.len() as size_t;
+        *success = 1 as u8;
+        ptr::copy_memory(&mut *buf, result.as_ptr() as *const c_void, result.len());
+        buf as *const c_char
+    }
+}
+
+extern "C" fn partial_merge_callback(
+    raw_cb: *mut c_void, key: *const c_char, key_len: size_t,
+    operands_list: *const *const c_char, operands_list_len: *const size_t,
+    num_operands: c_int,
+    success: *mut u8, new_value_length: *mut size_t) -> *const c_char {
+    unsafe {
+        let cb: &mut MergeOperatorCallback = &mut *(raw_cb as *mut MergeOperatorCallback);
+        let operands = &mut MergeOperands::new(operands_list, operands_list_len, num_operands);
+        let key = from_buf_len(key as *const u8, key_len as uint);
+        let mut result = (cb.merge_fn)(key.as_bytes(), None, operands);
+        result.shrink_to_fit();
+        //TODO(tan) investigate zero-copy techniques to improve performance
+        let buf = libc::malloc(result.len() as size_t);
+        assert!(buf.is_not_null());
+        *new_value_length = 1 as size_t;
+        *success = 1 as u8;
+        ptr::copy_memory(&mut *buf, result.as_ptr() as *const c_void, result.len());
+        buf as *const c_char
+    }
+}
+
+fn test_provided_merge<'a>(new_key: &[u8], existing_val: Option<&[u8]>,
+    mut operands: &mut MergeOperands) -> Vec<u8> {
+    let mut result: Vec<u8> = Vec::with_capacity(operands.size_hint().val0());
+    match existing_val {
+        Some(v) => result.push_all(v),
+        None => (),
+    }
+    for op in operands {
+        result.push_all(op);
+    }
+    result
+}
+
+#[allow(dead_code)]
+#[test]
+fn mergetest() {
+    let path = "_rust_rocksdb_mergetest";
+    unsafe {
+        let opts = RocksDBOptions::new();
+        opts.create_if_missing(true);
+        opts.add_merge_operator("test operator", test_provided_merge);
+        let db = RocksDB::open(opts, path).unwrap();
+        let p = db.put(b"k1", b"a");
+        assert!(p.is_ok());
+        db.merge(b"k1", b"b");
+        db.merge(b"k1", b"c");
+        db.merge(b"k1", b"d");
+        db.merge(b"k1", b"efg");
+        let m = db.merge(b"k1", b"h");
+        assert!(m.is_ok());
+        db.get(b"k1").map( |value| {
+            match value.to_utf8() {
+                Some(v) =>
+                    println!("retrieved utf8 value: {}", v),
+                None =>
+                    println!("did not read valid utf-8 out of the db"),
+            }
+        }).on_absent( || { println!("value not present!") })
+          .on_error( |e| { println!("error reading value")}); //: {}", e) });
+
+        assert!(m.is_ok());
+        let r: RocksDBResult<RocksDBVector, String> = db.get(b"k1");
+        assert!(r.unwrap().to_utf8().unwrap() == "abcdefgh");
+        assert!(db.delete(b"k1").is_ok());
+        assert!(db.get(b"k1").is_none());
+        db.close();
+        assert!(RocksDB::destroy(opts, path).is_ok());
+    }
 }