I have some query: EXPLAIN ANALYZE select id from sometable where fkey IS NOT DISTINCT FROM 21580; QUERY PLAN ---------------------------------------------------------------------------------------------------------------------------- Gather (cost=10.00..39465.11 rows=1 width=4) (actual time=0.512..129.625 rows=1 loops=1) Workers Planned: 4 Workers Launched: 4 -> Parallel Seq Scan on sometable (cost=0.00..39455.01 rows=1 width=4) (actual time=77.995..103.806 rows=0 loops=5) Filter: (NOT (fkey IS DISTINCT FROM 21580)) Rows Removed by Filter: 675238 Planning time: 0.101 ms Execution time: 148.517 ms Other Query: EXPLAIN ANALYZE select id from table where fkey=21580; QUERY PLAN ---------------------------------------------------------------------------------------------------------------------------------- Index Scan using sometable_index1 on sometable (cost=0.43..8.45 rows=1 width=4) (actual time=0.075..0.076 rows=1 loops=1) Index Cond: (fkey = 21580) Planning time: 0.117 ms Execution time: 0.101 ms (4 rows) There is unique index on sometable(fkey); Is there any reason that „NOT DISTINCT FROM” can’t be autotransformed to „=” when value on right side of _expression_ is not NULL or is this any way to use index with „IS NOT DISTINCT FROM” statement? Artur Zajac |
