diff --git a/src/database/mod.rs b/src/database/mod.rs
index 701a7e23b..ddc7e128d 100644
--- a/src/database/mod.rs
+++ b/src/database/mod.rs
@@ -1,3 +1,5 @@
+use crate::DocumentId;
+use crate::database::schema::SchemaAttr;
 use std::sync::Arc;
 use std::error::Error;
 use std::ffi::OsStr;
@@ -12,6 +14,7 @@ use rocksdb::rocksdb::{Writable, Snapshot};
 use rocksdb::rocksdb_options::{DBOptions, ColumnFamilyOptions};
 use rocksdb::{DB, MergeOperands};
 use lockfree::map::Map;
+use hashbrown::HashMap;
 
 pub use self::document_key::{DocumentKey, DocumentKeyAttr};
 pub use self::view::{DatabaseView, DocumentIter};
@@ -20,8 +23,9 @@ pub use self::serde::SerializerError;
 pub use self::schema::Schema;
 pub use self::index::Index;
 
-const DATA_INDEX:  &[u8] = b"data-index";
-const DATA_SCHEMA: &[u8] = b"data-schema";
+const DATA_INDEX:      &[u8] = b"data-index";
+const DATA_RANKED_MAP: &[u8] = b"data-ranked-map";
+const DATA_SCHEMA:     &[u8] = b"data-schema";
 
 pub mod schema;
 pub(crate) mod index;
@@ -61,9 +65,17 @@ where D: Deref<Target=DB>
     Ok(index)
 }
 
-fn merge_indexes(key: &[u8], existing: Option<&[u8]>, operands: &mut MergeOperands) -> Vec<u8> {
-    assert_eq!(key, DATA_INDEX, "The merge operator only supports \"data-index\" merging");
+fn retrieve_data_ranked_map<D>(snapshot: &Snapshot<D>)
+-> Result<HashMap<(DocumentId, SchemaAttr), i64>, Box<Error>>
+where D: Deref<Target=DB>
+{
+    match snapshot.get(DATA_RANKED_MAP)? {
+        Some(vector) => Ok(bincode::deserialize(&*vector)?),
+        None => Ok(HashMap::new()),
+    }
+}
 
+fn merge_indexes(existing: Option<&[u8]>, operands: &mut MergeOperands) -> Vec<u8> {
     let mut index: Option<Index> = None;
     for bytes in existing.into_iter().chain(operands) {
         let operand = Index::from_bytes(bytes.to_vec()).unwrap();
@@ -81,6 +93,28 @@ fn merge_indexes(key: &[u8], existing: Option<&[u8]>, operands: &mut MergeOperan
     bytes
 }
 
+fn merge_ranked_maps(existing: Option<&[u8]>, operands: &mut MergeOperands) -> Vec<u8> {
+    let mut ranked_map: Option<HashMap<_, _>> = None;
+    for bytes in existing.into_iter().chain(operands) {
+        let operand: HashMap<(DocumentId, SchemaAttr), i64> = bincode::deserialize(bytes).unwrap();
+        match ranked_map {
+            Some(ref mut ranked_map) => ranked_map.extend(operand),
+            None => { ranked_map.replace(operand); },
+        };
+    }
+
+    let ranked_map = ranked_map.unwrap_or_default();
+    bincode::serialize(&ranked_map).unwrap()
+}
+
+fn merge_operator(key: &[u8], existing: Option<&[u8]>, operands: &mut MergeOperands) -> Vec<u8> {
+    match key {
+        DATA_INDEX      => merge_indexes(existing, operands),
+        DATA_RANKED_MAP => merge_ranked_maps(existing, operands),
+        key             => panic!("The merge operator does not support merging {:?}", key),
+    }
+}
+
 pub struct IndexUpdate {
     index: String,
     update: Update,
@@ -103,14 +137,14 @@ impl DerefMut for IndexUpdate {
 struct DatabaseIndex {
     db: Arc<DB>,
 
-    // This view is updated each time the DB ingests an update
+    // This view is updated each time the DB ingests an update.
     view: ArcCell<DatabaseView<Arc<DB>>>,
 
-    // This path is the path to the mdb folder stored on disk
+    // The path of the mdb folder stored on disk.
     path: PathBuf,
 
     // must_die false by default, must be set as true when the Index is dropped.
-    // It's used to erase the folder saved on disk when the user request to delete an index
+    // It is used to erase the folder saved on disk when the user request to delete an index.
     must_die: AtomicBool,
 }
 
@@ -128,7 +162,7 @@ impl DatabaseIndex {
         // opts.error_if_exists(true); // FIXME pull request that
 
         let mut cf_opts = ColumnFamilyOptions::new();
-        cf_opts.add_merge_operator("data-index merge operator", merge_indexes);
+        cf_opts.add_merge_operator("data merge operator", merge_operator);
 
         let db = DB::open_cf(opts, &path_lossy, vec![("default", cf_opts)])?;
 
@@ -156,7 +190,7 @@ impl DatabaseIndex {
         opts.create_if_missing(false);
 
         let mut cf_opts = ColumnFamilyOptions::new();
-        cf_opts.add_merge_operator("data-index merge operator", merge_indexes);
+        cf_opts.add_merge_operator("data merge operator", merge_operator);
 
         let db = DB::open_cf(opts, &path_lossy, vec![("default", cf_opts)])?;
 
diff --git a/src/database/schema.rs b/src/database/schema.rs
index 5b4b48731..3a8878ee3 100644
--- a/src/database/schema.rs
+++ b/src/database/schema.rs
@@ -13,8 +13,9 @@ use crate::database::serde::find_id::FindDocumentIdSerializer;
 use crate::database::serde::SerializerError;
 use crate::DocumentId;
 
-pub const STORED: SchemaProps = SchemaProps { stored: true, indexed: false };
-pub const INDEXED: SchemaProps = SchemaProps { stored: false, indexed: true };
+pub const STORED: SchemaProps  = SchemaProps { stored: true,  indexed: false, ranked: false };
+pub const INDEXED: SchemaProps = SchemaProps { stored: false, indexed: true,  ranked: false };
+pub const RANKED: SchemaProps  = SchemaProps { stored: false, indexed: false, ranked: true  };
 
 #[derive(Debug, Copy, Clone, PartialEq, Eq, Serialize, Deserialize)]
 pub struct SchemaProps {
@@ -23,6 +24,9 @@ pub struct SchemaProps {
 
     #[serde(default)]
     indexed: bool,
+
+    #[serde(default)]
+    ranked: bool,
 }
 
 impl SchemaProps {
@@ -33,6 +37,10 @@ impl SchemaProps {
     pub fn is_indexed(self) -> bool {
         self.indexed
     }
+
+    pub fn is_ranked(self) -> bool {
+        self.ranked
+    }
 }
 
 impl BitOr for SchemaProps {
@@ -42,6 +50,7 @@ impl BitOr for SchemaProps {
         SchemaProps {
             stored: self.stored | other.stored,
             indexed: self.indexed | other.indexed,
+            ranked: self.ranked | other.ranked,
         }
     }
 }
@@ -185,7 +194,8 @@ impl Schema {
     }
 }
 
-#[derive(Debug, Copy, Clone, PartialOrd, Ord, PartialEq, Eq)]
+#[derive(Serialize, Deserialize)]
+#[derive(Debug, Copy, Clone, PartialOrd, Ord, PartialEq, Eq, Hash)]
 pub struct SchemaAttr(pub(crate) u16);
 
 impl SchemaAttr {
diff --git a/src/database/serde/mod.rs b/src/database/serde/mod.rs
index 2f9415c25..50a3c619e 100644
--- a/src/database/serde/mod.rs
+++ b/src/database/serde/mod.rs
@@ -17,6 +17,7 @@ macro_rules! forward_to_unserializable_type {
 
 pub mod find_id;
 pub mod key_to_string;
+pub mod value_to_i64;
 pub mod serializer;
 pub mod indexer_serializer;
 pub mod deserializer;
diff --git a/src/database/serde/serializer.rs b/src/database/serde/serializer.rs
index d516be609..bc8b4d1ab 100644
--- a/src/database/serde/serializer.rs
+++ b/src/database/serde/serializer.rs
@@ -5,6 +5,7 @@ use serde::ser;
 
 use crate::database::serde::indexer_serializer::IndexerSerializer;
 use crate::database::serde::key_to_string::KeyToStringSerializer;
+use crate::database::serde::value_to_i64::ValueToI64Serializer;
 use crate::database::update::DocumentUpdate;
 use crate::database::serde::SerializerError;
 use crate::tokenizer::TokenizerBuilder;
@@ -155,8 +156,8 @@ where B: TokenizerBuilder
     {
         Ok(StructSerializer {
             schema: self.schema,
-            update: self.update,
             document_id: self.document_id,
+            update: self.update,
             tokenizer_builder: self.tokenizer_builder,
             stop_words: self.stop_words,
         })
@@ -229,6 +230,10 @@ where B: TokenizerBuilder
                 };
                 value.serialize(serializer)?;
             }
+            if props.is_ranked() {
+                let integer = value.serialize(ValueToI64Serializer)?;
+                self.update.register_ranked_attribute(attr, integer)?;
+            }
         }
 
         Ok(())
@@ -276,6 +281,10 @@ where B: TokenizerBuilder
                 };
                 value.serialize(serializer)?;
             }
+            if props.is_ranked() {
+                let integer = value.serialize(ValueToI64Serializer)?;
+                self.update.register_ranked_attribute(attr, integer)?;
+            }
         }
 
         Ok(())
diff --git a/src/database/serde/value_to_i64.rs b/src/database/serde/value_to_i64.rs
new file mode 100644
index 000000000..9c046d391
--- /dev/null
+++ b/src/database/serde/value_to_i64.rs
@@ -0,0 +1,169 @@
+use serde::Serialize;
+use serde::{ser, ser::Error};
+
+use crate::database::serde::SerializerError;
+
+pub struct ValueToI64Serializer;
+
+impl ser::Serializer for ValueToI64Serializer {
+    type Ok = i64;
+    type Error = SerializerError;
+    type SerializeSeq = ser::Impossible<Self::Ok, Self::Error>;
+    type SerializeTuple = ser::Impossible<Self::Ok, Self::Error>;
+    type SerializeTupleStruct = ser::Impossible<Self::Ok, Self::Error>;
+    type SerializeTupleVariant = ser::Impossible<Self::Ok, Self::Error>;
+    type SerializeMap = ser::Impossible<Self::Ok, Self::Error>;
+    type SerializeStruct = ser::Impossible<Self::Ok, Self::Error>;
+    type SerializeStructVariant = ser::Impossible<Self::Ok, Self::Error>;
+
+    forward_to_unserializable_type! {
+        bool => serialize_bool,
+        char => serialize_char,
+
+        f32 => serialize_f32,
+        f64 => serialize_f64,
+    }
+
+    fn serialize_i8(self, value: i8) -> Result<Self::Ok, Self::Error> {
+        Ok(i64::from(value))
+    }
+
+    fn serialize_i16(self, value: i16) -> Result<Self::Ok, Self::Error> {
+        Ok(i64::from(value))
+    }
+
+    fn serialize_i32(self, value: i32) -> Result<Self::Ok, Self::Error> {
+        Ok(i64::from(value))
+    }
+
+    fn serialize_i64(self, value: i64) -> Result<Self::Ok, Self::Error> {
+        Ok(i64::from(value))
+    }
+
+    fn serialize_u8(self, value: u8) -> Result<Self::Ok, Self::Error> {
+        Ok(i64::from(value))
+    }
+
+    fn serialize_u16(self, value: u16) -> Result<Self::Ok, Self::Error> {
+        Ok(i64::from(value))
+    }
+
+    fn serialize_u32(self, value: u32) -> Result<Self::Ok, Self::Error> {
+        Ok(i64::from(value))
+    }
+
+    fn serialize_u64(self, value: u64) -> Result<Self::Ok, Self::Error> {
+        // Ok(i64::from(value))
+        unimplemented!()
+    }
+
+    fn serialize_str(self, value: &str) -> Result<Self::Ok, Self::Error> {
+        i64::from_str_radix(value, 10).map_err(SerializerError::custom)
+    }
+
+    fn serialize_bytes(self, _v: &[u8]) -> Result<Self::Ok, Self::Error> {
+        Err(SerializerError::UnserializableType { name: "&[u8]" })
+    }
+
+    fn serialize_none(self) -> Result<Self::Ok, Self::Error> {
+        Err(SerializerError::UnserializableType { name: "Option" })
+    }
+
+    fn serialize_some<T: ?Sized>(self, _value: &T) -> Result<Self::Ok, Self::Error>
+    where T: Serialize,
+    {
+        Err(SerializerError::UnserializableType { name: "Option" })
+    }
+
+    fn serialize_unit(self) -> Result<Self::Ok, Self::Error> {
+        Err(SerializerError::UnserializableType { name: "()" })
+    }
+
+    fn serialize_unit_struct(self, _name: &'static str) -> Result<Self::Ok, Self::Error> {
+        Err(SerializerError::UnserializableType { name: "unit struct" })
+    }
+
+    fn serialize_unit_variant(
+        self,
+        _name: &'static str,
+        _variant_index: u32,
+        _variant: &'static str
+    ) -> Result<Self::Ok, Self::Error>
+    {
+        Err(SerializerError::UnserializableType { name: "unit variant" })
+    }
+
+    fn serialize_newtype_struct<T: ?Sized>(
+        self,
+        _name: &'static str,
+        value: &T
+    ) -> Result<Self::Ok, Self::Error>
+    where T: Serialize,
+    {
+        value.serialize(self)
+    }
+
+    fn serialize_newtype_variant<T: ?Sized>(
+        self,
+        _name: &'static str,
+        _variant_index: u32,
+        _variant: &'static str,
+        _value: &T
+    ) -> Result<Self::Ok, Self::Error>
+    where T: Serialize,
+    {
+        Err(SerializerError::UnserializableType { name: "newtype variant" })
+    }
+
+    fn serialize_seq(self, _len: Option<usize>) -> Result<Self::SerializeSeq, Self::Error> {
+        Err(SerializerError::UnserializableType { name: "sequence" })
+    }
+
+    fn serialize_tuple(self, _len: usize) -> Result<Self::SerializeTuple, Self::Error> {
+        Err(SerializerError::UnserializableType { name: "tuple" })
+    }
+
+    fn serialize_tuple_struct(
+        self,
+        _name: &'static str,
+        _len: usize
+    ) -> Result<Self::SerializeTupleStruct, Self::Error>
+    {
+        Err(SerializerError::UnserializableType { name: "tuple struct" })
+    }
+
+    fn serialize_tuple_variant(
+        self,
+        _name: &'static str,
+        _variant_index: u32,
+        _variant: &'static str,
+        _len: usize
+    ) -> Result<Self::SerializeTupleVariant, Self::Error>
+    {
+        Err(SerializerError::UnserializableType { name: "tuple variant" })
+    }
+
+    fn serialize_map(self, _len: Option<usize>) -> Result<Self::SerializeMap, Self::Error> {
+        Err(SerializerError::UnserializableType { name: "map" })
+    }
+
+    fn serialize_struct(
+        self,
+        _name: &'static str,
+        _len: usize
+    ) -> Result<Self::SerializeStruct, Self::Error>
+    {
+        Err(SerializerError::UnserializableType { name: "struct" })
+    }
+
+    fn serialize_struct_variant(
+        self,
+        _name: &'static str,
+        _variant_index: u32,
+        _variant: &'static str,
+        _len: usize
+    ) -> Result<Self::SerializeStructVariant, Self::Error>
+    {
+        Err(SerializerError::UnserializableType { name: "struct variant" })
+    }
+}
diff --git a/src/database/update.rs b/src/database/update.rs
index 616c070e5..0c165550d 100644
--- a/src/database/update.rs
+++ b/src/database/update.rs
@@ -17,7 +17,7 @@ use crate::data::{DocIds, DocIndexes};
 use crate::database::schema::Schema;
 use crate::database::index::Index;
 use crate::{DocumentId, DocIndex};
-use crate::database::DATA_INDEX;
+use crate::database::{DATA_INDEX, DATA_RANKED_MAP};
 
 pub type Token = Vec<u8>; // TODO could be replaced by a SmallVec
 
@@ -78,6 +78,7 @@ use UpdateType::{Updated, Deleted};
 
 pub struct RawUpdateBuilder {
     documents_update: HashMap<DocumentId, UpdateType>,
+    documents_ranked_fields: HashMap<(DocumentId, SchemaAttr), i64>,
     indexed_words: BTreeMap<Token, Vec<DocIndex>>,
     batch: WriteBatch,
 }
@@ -86,6 +87,7 @@ impl RawUpdateBuilder {
     pub fn new() -> RawUpdateBuilder {
         RawUpdateBuilder {
             documents_update: HashMap::new(),
+            documents_ranked_fields: HashMap::new(),
             indexed_words: BTreeMap::new(),
             batch: WriteBatch::new(),
         }
@@ -137,9 +139,12 @@ impl RawUpdateBuilder {
         let index = Index { negative, positive };
 
         // write the data-index
-        let mut bytes = Vec::new();
-        index.write_to_bytes(&mut bytes);
-        self.batch.merge(DATA_INDEX, &bytes)?;
+        let mut bytes_index = Vec::new();
+        index.write_to_bytes(&mut bytes_index);
+        self.batch.merge(DATA_INDEX, &bytes_index)?;
+
+        let bytes_ranked_map = bincode::serialize(&self.documents_ranked_fields).unwrap();
+        self.batch.merge(DATA_RANKED_MAP, &bytes_ranked_map)?;
 
         Ok(self.batch)
     }
@@ -195,4 +200,23 @@ impl<'a> DocumentUpdate<'a> {
 
         Ok(())
     }
+
+    pub fn register_ranked_attribute(
+        &mut self,
+        attr: SchemaAttr,
+        integer: i64,
+    ) -> Result<(), SerializerError>
+    {
+        use serde::ser::Error;
+
+        if let Deleted = self.inner.documents_update.entry(self.document_id).or_insert(Updated) {
+            return Err(SerializerError::custom(
+                "This document has already been deleted, ranked attributes cannot be added in the same update"
+            ));
+        }
+
+        self.inner.documents_ranked_fields.insert((self.document_id, attr), integer);
+
+        Ok(())
+    }
 }
diff --git a/src/database/view.rs b/src/database/view.rs
index b9144a281..6f04ac4b1 100644
--- a/src/database/view.rs
+++ b/src/database/view.rs
@@ -1,3 +1,4 @@
+use hashbrown::HashMap;
 use std::error::Error;
 use std::path::Path;
 use std::ops::Deref;
@@ -7,12 +8,13 @@ use rocksdb::rocksdb_options::{ReadOptions, EnvOptions, ColumnFamilyOptions};
 use rocksdb::rocksdb::{DB, DBVector, Snapshot, SeekKey, SstFileWriter};
 use serde::de::DeserializeOwned;
 
-use crate::database::{DocumentKey, DocumentKeyAttr};
-use crate::database::{retrieve_data_schema, retrieve_data_index};
+use crate::database::{retrieve_data_schema, retrieve_data_index, retrieve_data_ranked_map};
 use crate::database::serde::deserializer::Deserializer;
+use crate::database::{DocumentKey, DocumentKeyAttr};
+use crate::rank::{QueryBuilder, FilterFunc};
+use crate::database::schema::SchemaAttr;
 use crate::database::schema::Schema;
 use crate::database::index::Index;
-use crate::rank::{QueryBuilder, FilterFunc};
 use crate::DocumentId;
 
 pub struct DatabaseView<D>
@@ -20,6 +22,7 @@ where D: Deref<Target=DB>
 {
     snapshot: Snapshot<D>,
     index: Index,
+    ranked_map: HashMap<(DocumentId, SchemaAttr), i64>,
     schema: Schema,
 }
 
@@ -29,7 +32,8 @@ where D: Deref<Target=DB>
     pub fn new(snapshot: Snapshot<D>) -> Result<DatabaseView<D>, Box<Error>> {
         let schema = retrieve_data_schema(&snapshot)?;
         let index = retrieve_data_index(&snapshot)?;
-        Ok(DatabaseView { snapshot, index, schema })
+        let ranked_map = retrieve_data_ranked_map(&snapshot)?;
+        Ok(DatabaseView { snapshot, index, ranked_map, schema })
     }
 
     pub fn schema(&self) -> &Schema {
@@ -40,6 +44,10 @@ where D: Deref<Target=DB>
         &self.index
     }
 
+    pub fn ranked_map(&self) -> &HashMap<(DocumentId, SchemaAttr), i64> {
+        &self.ranked_map
+    }
+
     pub fn into_snapshot(self) -> Snapshot<D> {
         self.snapshot
     }
diff --git a/src/lib.rs b/src/lib.rs
index bfa0b3cd9..9c0641090 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -7,6 +7,8 @@ pub mod rank;
 pub mod tokenizer;
 mod common_words;
 
+use serde_derive::{Serialize, Deserialize};
+
 pub use rocksdb;
 
 pub use self::tokenizer::Tokenizer;
@@ -16,6 +18,7 @@ pub use self::common_words::CommonWords;
 ///
 /// It is used to inform the database the document you want to deserialize.
 /// Helpful for custom ranking.
+#[derive(Serialize, Deserialize)]
 #[derive(Debug, Copy, Clone, Eq, PartialEq, PartialOrd, Ord, Hash)]
 pub struct DocumentId(u64);