Re: Query with rightmost function does not use index - Mailing list pgsql-general

Here are the EXPLAIN ANALYZE outputs:


explain analyze select * from filter_item where filter_hash = MD5('');

                                                      QUERY PLAN                                                      
-----------------------------------------------------------------------------------------------------------------------
 Seq Scan on filter_item  (cost=0.00..424644.96 rows=86108 width=49) (ac tual time=8177.807..12421.921 rows=77 loops=1)
   Filter: ((filter_hash)::text = 'd41d8cd98f00b204e9800998ecf8427e'::text)
 Total runtime: 12421.959 ms
(3 rows)


explain analyze select * from filter_item where filter_hash = 'd41d8cd98f00b204e9800998ecf8427e'

                                                             QUERY PLAN                                                              
--------------------------------------------------------------------------------------------------------------------------------------
 Bitmap Heap Scan on filter_item  (cost=77.92..6609.02 rows=3534 width=49) (actual time=0.055..0.100 rows=77 loops=1)
   Recheck Cond: (filter_hash = 'd41d8cd98f00b204e9800998ecf8427e'::bpchar)
   ->  Bitmap Index Scan on filter_item__filter_hash  (cost=0.00..77.04 rows=3534 width=0) (actual time=0.049..0.049 rows=77 loops=1)
         Index Cond: (filter_hash = 'd41d8cd98f00b204e9800998ecf8427e'::bpchar)
 Total runtime: 0.130 ms
(5 rows)