Проблема с PostgreSQL. При использовании LIMIT не используется индекс.

feeds=# \d facets
              Table "public.facets"
    Column    |  Type   |       Modifiers        
--------------+---------+------------------------
 product_id   | bigint  | not null
 warehouse_id | bigint  | not null
 field_id     | bigint  | not null
 value        | text    | not null
 locked       | boolean | not null default false
Indexes:
    "unique_facet" UNIQUE CONSTRAINT, btree (product_id, warehouse_id, field_id)
    "facets_value" gin (value gin_trgm_ops)
Check constraints:
    "facets_value_long_enough" CHECK (value <> ''::text)
    "facets_value_trimmed" CHECK (btrim(value) = value)
Foreign-key constraints:
    "facets_field_id_fkey" FOREIGN KEY (field_id) REFERENCES fields(id) ON DELETE CASCADE
    "facets_product_id_fkey" FOREIGN KEY (product_id) REFERENCES products(id) ON DELETE CASCADE
    "facets_warehouse_id_fkey" FOREIGN KEY (warehouse_id) REFERENCES warehouses(id) ON DELETE CASCADE

feeds=# SELECT DISTINCT facets.product_id FROM facets WHERE facets.value ILIKE '%0731304123538%' ORDER BY facets.product_id offset 0;
 product_id 
------------
    1767628
    1787052
    1787365
    2271634
(4 rows)

Time: 26.715 ms
feeds=# explain SELECT DISTINCT facets.product_id FROM facets WHERE facets.value ILIKE '%0731304123538%' ORDER BY facets.product_id offset 0;
                                         QUERY PLAN                                          
---------------------------------------------------------------------------------------------
 Unique  (cost=9759.46..9770.67 rows=2236 width=8)
   ->  Sort  (cost=9759.46..9765.07 rows=2242 width=8)
         Sort Key: product_id
         ->  Bitmap Heap Scan on facets  (cost=1269.37..9634.69 rows=2242 width=8)
               Recheck Cond: (value ~~* '%0731304123538%'::text)
               ->  Bitmap Index Scan on facets_value  (cost=0.00..1268.81 rows=2242 width=0)
                     Index Cond: (value ~~* '%0731304123538%'::text)
(7 rows)

Time: 0.824 ms

feeds=# explain SELECT DISTINCT facets.product_id FROM facets WHERE facets.value ILIKE '%0731304123538%' ORDER BY facets.product_id offset 0 limit 10;
                                           QUERY PLAN                                           
------------------------------------------------------------------------------------------------
 Limit  (cost=0.56..8557.31 rows=10 width=8)
   ->  Unique  (cost=0.56..1913289.72 rows=2236 width=8)
         ->  Index Scan using unique_facet on facets  (cost=0.56..1913284.12 rows=2242 width=8)
               Filter: (value ~~* '%0731304123538%'::text)
(4 rows)

Time: 1.523 ms
feeds=# SELECT DISTINCT facets.product_id FROM facets WHERE facets.value ILIKE '%0731304123538%' ORDER BY facets.product_id offset 0 limit 10;
 product_id 
------------
    1767628
    1787052
    1787365
    2271634
(4 rows)

Time: 27863.692 ms