diff --git a/CHANGELOG b/CHANGELOG
index 9ad08464eb..528e3be317 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,3 +1,4 @@
+* Add sql_id method to Reference field
 * Use declarative index definition for ModelSQL
 * Add configuration entries for unaccent and similarity functions
 * Add authentication services
diff --git a/doc/ref/fields.rst b/doc/ref/fields.rst
index b2c1a9fe07..0cfd87e6d1 100644
--- a/doc/ref/fields.rst
+++ b/doc/ref/fields.rst
@@ -684,6 +684,10 @@ Instance methods:
    Same as :meth:`~Selection.translated` but for the translated name of the
    target model.
 
+.. method:: Reference.sql_id(column, Model)
+
+   Return the SQL expression that extract the record ID of the column.
+
 
 Many2One
 --------
diff --git a/trytond/model/fields/many2many.py b/trytond/model/fields/many2many.py
index 54ccf3c0c3..b3e66e04f6 100644
--- a/trytond/model/fields/many2many.py
+++ b/trytond/model/fields/many2many.py
@@ -3,9 +3,8 @@
 from collections import defaultdict
 from itertools import chain
 
-from sql import Cast, Literal, Null
+from sql import Literal, Null
 from sql.conditionals import Coalesce
-from sql.functions import Position, Substring
 
 from trytond.pool import Pool
 from trytond.pyson import PYSONEncoder
@@ -379,9 +378,7 @@ class Many2Many(Field):
         origin_where = None
         if origin_field._type == 'reference':
             origin_where = origin.like(Model.__name__ + ',%')
-            origin = Cast(Substring(origin,
-                    Position(',', origin) + Literal(1)),
-                Relation.id.sql_type().base)
+            origin = origin_field.sql_id(origin, Relation)
 
         target = getattr(Relation, self.target).sql_column(relation)
         if '.' not in name:
diff --git a/trytond/model/fields/one2many.py b/trytond/model/fields/one2many.py
index 1f8604163e..711202988f 100644
--- a/trytond/model/fields/one2many.py
+++ b/trytond/model/fields/one2many.py
@@ -3,9 +3,7 @@
 from collections import defaultdict
 from itertools import chain
 
-from sql import Cast, Literal
 from sql.conditionals import Coalesce
-from sql.functions import Position, Substring
 
 from trytond.pool import Pool
 from trytond.pyson import PYSONEncoder
@@ -332,9 +330,7 @@ class One2Many(Field):
         origin_where = None
         if origin_field._type == 'reference':
             origin_where = origin.like(Model.__name__ + ',%')
-            origin = Cast(Substring(origin,
-                    Position(',', origin) + Literal(1)),
-                Target.id.sql_type().base)
+            origin = origin_field.sql_id(origin, Target)
 
         if '.' not in name:
             if value is None:
diff --git a/trytond/model/fields/reference.py b/trytond/model/fields/reference.py
index 33b44569fb..2aa9c6a96e 100644
--- a/trytond/model/fields/reference.py
+++ b/trytond/model/fields/reference.py
@@ -187,6 +187,12 @@ class Reference(SelectionMixin, Field):
                 value = str(value)
         return super(Reference, self).sql_format(value)
 
+    def sql_id(self, column, Model):
+        "Return SQL expression for the id part of the field"
+        return Cast(Substring(
+                column, Position(',', column) + Literal(1)),
+            Model.id.sql_type().base)
+
     @with_inactive_records
     def convert_domain(self, domain, tables, Model):
         if '.' not in domain[0]:
@@ -203,9 +209,8 @@ class Reference(SelectionMixin, Field):
         if 'active' in Target._fields:
             target_domain.append(('active', 'in', [True, False]))
         query = Target.search(target_domain, order=[], query=True)
-        return (Cast(Substring(column,
-                    Position(',', column) + Literal(1)),
-                Model.id.sql_type().base).in_(query)
+        return (
+            self.sql_id(column, Model).in_(query)
             & column.like(target + ',%'))
 
     def definition(self, model, language):
diff --git a/trytond/model/modelsql.py b/trytond/model/modelsql.py
index 66bc79f18e..18687fcead 100644
--- a/trytond/model/modelsql.py
+++ b/trytond/model/modelsql.py
@@ -318,6 +318,8 @@ class ModelSQL(ModelStorage):
                             Index(
                                 target,
                                 (column, Index.Similarity(begin=True)),
+                                (target_field.sql_id(column, Target),
+                                    Index.Range()),
                                 where=where),
                             })
                 else: