here is test2 table with only one column id erp_test=> \d test2 Table "public.test2" Column | Type | Modifiers --------+---------+----------- id | integer |
I insert 10,000,000 entries in this table. erp_test=> INSERT INTO test2 VALUES (generate_series(1,10000000)); INSERT 0 10000000
then i delete all the entries erp_test=> delete from test2; DELETE 10000000
and i insert only 10 entries erp_test=> INSERT INTO test2 VALUES (generate_series(1,10)); INSERT 0 10
now i try to count no of rows in this table which take long time for this 10 rows only (about 2-3 second) erp_test=> SELECT count(*) from test2; count ------- 10 (1 row)
this is the output of explain analyze query of the same
erp_test=> EXPLAIN ANALYZE SELECT count(*) from test2; QUERY PLAN ------------------------------------------------------------------------------------------------------------------------ Aggregate (cost=198652.13..198652.14 rows=1 width=0) (actual time=2123.471..2123.472 rows=1 loops=1) -> Seq Scan on test2 (cost=0.00..169732.70 rows=11567770 width=0) (actual time=2123.454..2123.454 rows=10 loops=1) Total runtime: 2123.609 ms (3 rows)
can any one solve my problem to speed up my select count query.
