diff --git a/src/rank/criterion/document_id.rs b/src/rank/criterion/document_id.rs
index 2d8ca34c2..a388cf2de 100644
--- a/src/rank/criterion/document_id.rs
+++ b/src/rank/criterion/document_id.rs
@@ -1,19 +1,14 @@
 use std::cmp::Ordering;
 use std::ops::Deref;
 
-use rocksdb::DB;
-
 use crate::rank::criterion::Criterion;
-use crate::database::DatabaseView;
-use crate::rank::Document;
+use crate::rank::RawDocument;
 
 #[derive(Debug, Clone, Copy)]
 pub struct DocumentId;
 
-impl<D> Criterion<D> for DocumentId
-where D: Deref<Target=DB>
-{
-    fn evaluate(&self, lhs: &Document, rhs: &Document, _: &DatabaseView<D>) -> Ordering {
+impl Criterion for DocumentId {
+    fn evaluate(&self, lhs: &RawDocument, rhs: &RawDocument) -> Ordering {
         lhs.id.cmp(&rhs.id)
     }
 }
diff --git a/src/rank/criterion/mod.rs b/src/rank/criterion/mod.rs
index c7c547851..46b41ea0f 100644
--- a/src/rank/criterion/mod.rs
+++ b/src/rank/criterion/mod.rs
@@ -19,60 +19,51 @@ pub use self::{
     sum_of_words_attribute::SumOfWordsAttribute,
     sum_of_words_position::SumOfWordsPosition,
     exact::Exact,
-    sort_by::SortBy,
+    // sort_by::SortBy,
     document_id::DocumentId,
 };
 
-pub trait Criterion<D>
-where D: Deref<Target=DB>
-{
-    fn evaluate(&self, lhs: &Document, rhs: &Document, view: &DatabaseView<D>) -> Ordering;
+pub trait Criterion: Send + Sync {
+    fn evaluate(&self, lhs: &RawDocument, rhs: &RawDocument) -> Ordering;
 
     #[inline]
-    fn eq(&self, lhs: &Document, rhs: &Document, view: &DatabaseView<D>) -> bool {
-        self.evaluate(lhs, rhs, view) == Ordering::Equal
+    fn eq(&self, lhs: &RawDocument, rhs: &RawDocument) -> bool {
+        self.evaluate(lhs, rhs) == Ordering::Equal
     }
 }
 
-impl<'a, D, T: Criterion<D> + ?Sized> Criterion<D> for &'a T
-where D: Deref<Target=DB>
-{
-    fn evaluate(&self, lhs: &Document, rhs: &Document, view: &DatabaseView<D>) -> Ordering {
-        (**self).evaluate(lhs, rhs, view)
+impl<'a, T: Criterion + ?Sized + Send + Sync> Criterion for &'a T {
+    fn evaluate(&self, lhs: &RawDocument, rhs: &RawDocument) -> Ordering {
+        (**self).evaluate(lhs, rhs)
     }
 
-    fn eq(&self, lhs: &Document, rhs: &Document, view: &DatabaseView<D>) -> bool {
-        (**self).eq(lhs, rhs, view)
+    fn eq(&self, lhs: &RawDocument, rhs: &RawDocument) -> bool {
+        (**self).eq(lhs, rhs)
     }
 }
 
-impl<D, T: Criterion<D> + ?Sized> Criterion<D> for Box<T>
-where D: Deref<Target=DB>
-{
-    fn evaluate(&self, lhs: &Document, rhs: &Document, view: &DatabaseView<D>) -> Ordering {
-        (**self).evaluate(lhs, rhs, view)
+impl<T: Criterion + ?Sized> Criterion for Box<T> {
+    fn evaluate(&self, lhs: &RawDocument, rhs: &RawDocument) -> Ordering {
+        (**self).evaluate(lhs, rhs)
     }
 
-    fn eq(&self, lhs: &Document, rhs: &Document, view: &DatabaseView<D>) -> bool {
-        (**self).eq(lhs, rhs, view)
+    fn eq(&self, lhs: &RawDocument, rhs: &RawDocument) -> bool {
+        (**self).eq(lhs, rhs)
     }
 }
 
 #[derive(Default)]
-pub struct CriteriaBuilder<D>
-where D: Deref<Target=DB>
-{
-    inner: Vec<Box<dyn Criterion<D>>>
+pub struct CriteriaBuilder {
+    inner: Vec<Box<dyn Criterion>>
 }
 
-impl<D> CriteriaBuilder<D>
-where D: Deref<Target=DB>
+impl CriteriaBuilder
 {
-    pub fn new() -> CriteriaBuilder<D> {
+    pub fn new() -> CriteriaBuilder {
         CriteriaBuilder { inner: Vec::new() }
     }
 
-    pub fn with_capacity(capacity: usize) -> CriteriaBuilder<D> {
+    pub fn with_capacity(capacity: usize) -> CriteriaBuilder {
         CriteriaBuilder { inner: Vec::with_capacity(capacity) }
     }
 
@@ -80,33 +71,29 @@ where D: Deref<Target=DB>
         self.inner.reserve(additional)
     }
 
-    pub fn add<C>(mut self, criterion: C) -> CriteriaBuilder<D>
-    where C: 'static + Criterion<D>,
+    pub fn add<C>(mut self, criterion: C) -> CriteriaBuilder
+    where C: 'static + Criterion,
     {
         self.push(criterion);
         self
     }
 
     pub fn push<C>(&mut self, criterion: C)
-    where C: 'static + Criterion<D>,
+    where C: 'static + Criterion,
     {
         self.inner.push(Box::new(criterion));
     }
 
-    pub fn build(self) -> Criteria<D> {
+    pub fn build(self) -> Criteria {
         Criteria { inner: self.inner }
     }
 }
 
-pub struct Criteria<D>
-where D: Deref<Target=DB>
-{
-    inner: Vec<Box<dyn Criterion<D>>>,
+pub struct Criteria {
+    inner: Vec<Box<dyn Criterion>>,
 }
 
-impl<D> Default for Criteria<D>
-where D: Deref<Target=DB>
-{
+impl Default for Criteria {
     fn default() -> Self {
         CriteriaBuilder::with_capacity(7)
             .add(SumOfTypos)
@@ -120,10 +107,8 @@ where D: Deref<Target=DB>
     }
 }
 
-impl<D> AsRef<[Box<dyn Criterion<D>>]> for Criteria<D>
-where D: Deref<Target=DB>
-{
-    fn as_ref(&self) -> &[Box<dyn Criterion<D>>] {
+impl AsRef<[Box<dyn Criterion>]> for Criteria {
+    fn as_ref(&self) -> &[Box<dyn Criterion>] {
         &self.inner
     }
 }
diff --git a/src/rank/criterion/sort_by.rs b/src/rank/criterion/sort_by.rs
index 53b8bcac1..1604a492a 100644
--- a/src/rank/criterion/sort_by.rs
+++ b/src/rank/criterion/sort_by.rs
@@ -66,7 +66,7 @@ impl<T, D> Criterion<D> for SortBy<T>
 where D: Deref<Target=DB>,
       T: DeserializeOwned + Ord,
 {
-    fn evaluate(&self, lhs: &Document, rhs: &Document, view: &DatabaseView<D>) -> Ordering {
+    fn evaluate(&self, lhs: &RawDocument, rhs: &RawDocument, view: &DatabaseView<D>) -> Ordering {
         let lhs = match view.document_by_id::<T>(lhs.id) {
             Ok(doc) => Some(doc),
             Err(e) => { eprintln!("{}", e); None },
diff --git a/src/rank/query_builder.rs b/src/rank/query_builder.rs
index 11fc75498..ff160da7f 100644
--- a/src/rank/query_builder.rs
+++ b/src/rank/query_builder.rs
@@ -43,7 +43,7 @@ pub struct QueryBuilder<'a, D, FI>
 where D: Deref<Target=DB>
 {
     view: &'a DatabaseView<D>,
-    criteria: Criteria<D>,
+    criteria: Criteria,
     filter: Option<FI>,
 }
 
@@ -58,7 +58,7 @@ where D: Deref<Target=DB>
 impl<'a, D, FI> QueryBuilder<'a, D, FI>
 where D: Deref<Target=DB>,
 {
-    pub fn with_criteria(view: &'a DatabaseView<D>, criteria: Criteria<D>) -> Result<Self, Box<Error>> {
+    pub fn with_criteria(view: &'a DatabaseView<D>, criteria: Criteria) -> Result<Self, Box<Error>> {
         Ok(QueryBuilder { view, criteria, filter: None })
     }
 
@@ -165,12 +165,12 @@ where D: Deref<Target=DB>,
                     continue;
                 }
 
-                let (elapsed, ()) = elapsed::measure_time(|| {
-                    group.sort_unstable_by(|a, b| criterion.evaluate(a, b, view));
+                let (elapsed, _) = measure_time(|| {
+                    group.par_sort_unstable_by(|a, b| criterion.evaluate(a, b));
                 });
                 info!("criterion {} sort took {}", ci, elapsed);
 
-                for group in group.binary_group_by_mut(|a, b| criterion.eq(a, b, view)) {
+                for group in group.binary_group_by_mut(|a, b| criterion.eq(a, b)) {
                     documents_seen += group.len();
                     groups.push(group);