diff --git a/src/database/document_key.rs b/src/database/document_key.rs
new file mode 100644
index 000000000..09eba8067
--- /dev/null
+++ b/src/database/document_key.rs
@@ -0,0 +1,96 @@
+use std::io::{Cursor, Read, Write};
+use std::mem::size_of;
+
+use byteorder::{NativeEndian, WriteBytesExt, ReadBytesExt};
+
+use crate::index::schema::SchemaAttr;
+use crate::DocumentId;
+
+const DOC_KEY_LEN:      usize = 4 + size_of::<u64>();
+const DOC_KEY_ATTR_LEN: usize = DOC_KEY_LEN + 1 + size_of::<u32>();
+
+#[derive(Copy, Clone)]
+pub struct DocumentKey([u8; DOC_KEY_LEN]);
+
+impl DocumentKey {
+    pub fn new(id: DocumentId) -> DocumentKey {
+        let mut buffer = [0; DOC_KEY_LEN];
+
+        let mut wtr = Cursor::new(&mut buffer[..]);
+        wtr.write_all(b"doc-").unwrap();
+        wtr.write_u64::<NativeEndian>(id).unwrap();
+
+        DocumentKey(buffer)
+    }
+
+    pub fn from_bytes(mut bytes: &[u8]) -> DocumentKey {
+        assert!(bytes.len() >= DOC_KEY_LEN);
+        assert_eq!(&bytes[..4], b"doc-");
+
+        let mut buffer = [0; DOC_KEY_LEN];
+        bytes.read_exact(&mut buffer).unwrap();
+
+        DocumentKey(buffer)
+    }
+
+    pub fn with_attribute(&self, attr: SchemaAttr) -> DocumentKeyAttr {
+        DocumentKeyAttr::new(self.document_id(), attr)
+    }
+
+    pub fn document_id(&self) -> DocumentId {
+        (&self.0[4..]).read_u64::<NativeEndian>().unwrap()
+    }
+}
+
+impl AsRef<[u8]> for DocumentKey {
+    fn as_ref(&self) -> &[u8] {
+        &self.0
+    }
+}
+
+#[derive(Copy, Clone)]
+pub struct DocumentKeyAttr([u8; DOC_KEY_ATTR_LEN]);
+
+impl DocumentKeyAttr {
+    pub fn new(id: DocumentId, attr: SchemaAttr) -> DocumentKeyAttr {
+        let mut buffer = [0; DOC_KEY_ATTR_LEN];
+        let DocumentKey(raw_key) = DocumentKey::new(id);
+
+        let mut wtr = Cursor::new(&mut buffer[..]);
+        wtr.write_all(&raw_key).unwrap();
+        wtr.write_all(b"-").unwrap();
+        wtr.write_u32::<NativeEndian>(attr.as_u32()).unwrap();
+
+        DocumentKeyAttr(buffer)
+    }
+
+    pub fn from_bytes(mut bytes: &[u8]) -> DocumentKeyAttr {
+        assert!(bytes.len() >= DOC_KEY_ATTR_LEN);
+        assert_eq!(&bytes[..4], b"doc-");
+
+        let mut buffer = [0; DOC_KEY_ATTR_LEN];
+        bytes.read_exact(&mut buffer).unwrap();
+
+        DocumentKeyAttr(buffer)
+    }
+
+    pub fn document_id(&self) -> DocumentId {
+        (&self.0[4..]).read_u64::<NativeEndian>().unwrap()
+    }
+
+    pub fn attribute(&self) -> SchemaAttr {
+        let offset = 4 + size_of::<u64>() + 1;
+        let value = (&self.0[offset..]).read_u32::<NativeEndian>().unwrap();
+        SchemaAttr::new(value)
+    }
+
+    pub fn into_document_key(self) -> DocumentKey {
+        DocumentKey::new(self.document_id())
+    }
+}
+
+impl AsRef<[u8]> for DocumentKeyAttr {
+    fn as_ref(&self) -> &[u8] {
+        &self.0
+    }
+}
diff --git a/src/database/mod.rs b/src/database/mod.rs
index 3d8e6e184..2cc38c72c 100644
--- a/src/database/mod.rs
+++ b/src/database/mod.rs
@@ -1,27 +1,24 @@
-use std::io::{Cursor, Read, Write};
 use std::{fmt, marker};
 use std::error::Error;
-use std::mem::size_of;
 use std::path::Path;
 
-use rocksdb::rocksdb::{DB, Snapshot, DBVector};
+use rocksdb::rocksdb::{DB, Snapshot};
 use rocksdb::rocksdb_options::ReadOptions;
-use byteorder::{NativeEndian, WriteBytesExt, ReadBytesExt};
 use serde::de::{DeserializeOwned, Visitor};
 use serde::de::value::MapDeserializer;
 use serde::forward_to_deserialize_any;
 
-use crate::index::schema::{Schema, SchemaAttr};
+use crate::index::schema::Schema;
 use crate::blob::positive::PositiveBlob;
 use crate::index::update::Update;
+use crate::database::document_key::{DocumentKey, DocumentKeyAttr};
 use crate::DocumentId;
 
+pub mod document_key;
+
 const DATA_INDEX:  &[u8] = b"data-index";
 const DATA_SCHEMA: &[u8] = b"data-schema";
 
-const DOC_KEY_LEN:      usize = 4 + size_of::<u64>();
-const DOC_KEY_ATTR_LEN: usize = DOC_KEY_LEN + 1 + size_of::<u32>();
-
 // FIXME Do not panic!
 fn retrieve_data_schema(snapshot: &Snapshot<&DB>) -> Result<Schema, Box<Error>> {
     match snapshot.get(DATA_SCHEMA)? {
@@ -37,92 +34,6 @@ fn retrieve_data_index(snapshot: &Snapshot<&DB>) -> Result<PositiveBlob, Box<Err
     }
 }
 
-#[derive(Copy, Clone)]
-pub struct DocumentKey([u8; DOC_KEY_LEN]);
-
-impl DocumentKey {
-    pub fn new(id: DocumentId) -> DocumentKey {
-        let mut buffer = [0; DOC_KEY_LEN];
-
-        let mut wtr = Cursor::new(&mut buffer[..]);
-        wtr.write_all(b"doc-").unwrap();
-        wtr.write_u64::<NativeEndian>(id).unwrap();
-
-        DocumentKey(buffer)
-    }
-
-    pub fn from_bytes(mut bytes: &[u8]) -> DocumentKey {
-        assert!(bytes.len() >= DOC_KEY_LEN);
-        assert_eq!(&bytes[..4], b"doc-");
-
-        let mut buffer = [0; DOC_KEY_LEN];
-        bytes.read_exact(&mut buffer).unwrap();
-
-        DocumentKey(buffer)
-    }
-
-    pub fn with_attribute(&self, attr: SchemaAttr) -> DocumentKeyAttr {
-        DocumentKeyAttr::new(self.document_id(), attr)
-    }
-
-    pub fn document_id(&self) -> DocumentId {
-        (&self.0[4..]).read_u64::<NativeEndian>().unwrap()
-    }
-}
-
-impl AsRef<[u8]> for DocumentKey {
-    fn as_ref(&self) -> &[u8] {
-        &self.0
-    }
-}
-
-#[derive(Copy, Clone)]
-pub struct DocumentKeyAttr([u8; DOC_KEY_ATTR_LEN]);
-
-impl DocumentKeyAttr {
-    pub fn new(id: DocumentId, attr: SchemaAttr) -> DocumentKeyAttr {
-        let mut buffer = [0; DOC_KEY_ATTR_LEN];
-        let DocumentKey(raw_key) = DocumentKey::new(id);
-
-        let mut wtr = Cursor::new(&mut buffer[..]);
-        wtr.write_all(&raw_key).unwrap();
-        wtr.write_all(b"-").unwrap();
-        wtr.write_u32::<NativeEndian>(attr.as_u32()).unwrap();
-
-        DocumentKeyAttr(buffer)
-    }
-
-    pub fn from_bytes(mut bytes: &[u8]) -> DocumentKeyAttr {
-        assert!(bytes.len() >= DOC_KEY_ATTR_LEN);
-        assert_eq!(&bytes[..4], b"doc-");
-
-        let mut buffer = [0; DOC_KEY_ATTR_LEN];
-        bytes.read_exact(&mut buffer).unwrap();
-
-        DocumentKeyAttr(buffer)
-    }
-
-    pub fn document_id(&self) -> DocumentId {
-        (&self.0[4..]).read_u64::<NativeEndian>().unwrap()
-    }
-
-    pub fn attribute(&self) -> SchemaAttr {
-        let offset = 4 + size_of::<u64>() + 1;
-        let value = (&self.0[offset..]).read_u32::<NativeEndian>().unwrap();
-        SchemaAttr::new(value)
-    }
-
-    pub fn into_document_key(self) -> DocumentKey {
-        DocumentKey::new(self.document_id())
-    }
-}
-
-impl AsRef<[u8]> for DocumentKeyAttr {
-    fn as_ref(&self) -> &[u8] {
-        &self.0
-    }
-}
-
 pub struct Database(DB);
 
 impl Database {