On Thu, Jul 20, 2023 at 7:36 PM gzh <gzhcoder@xxxxxxx> wrote: > > > Thank you very much for taking the time to reply to my question. > > > Sorry, I provided incorrect information. > > The index also does not work in the following query statement. > > > > select COUNT(ET_CD) > > > from TBL_SHA > > > WHERE MS_CD = '009' > > > AND ETRYS = '000001' > > > QUERY PLAN > > Limit (cost=2419643.47..2419643.48 rows=1 width=8) (actual time=128667.439..128668.250 rows=1 loops=1) > > -> Finalize Aggregate (cost=2419643.47..2419643.48 rows=1 width=8) (actual time=128667.437..128668.246 rows=1 loops=1) > > -> Gather (cost=2419643.25..2419643.46 rows=2 width=8) (actual time=128664.108..128668.233 rows=3 loops=1) > > Workers Planned: 2 > > Workers Launched: 2 > > -> Partial Aggregate (cost=2418643.25..2418643.26 rows=1 width=8) (actual time=128655.256..128655.258 rows=1 loops=3) > > -> Parallel Seq Scan on TBL_SHA (cost=0.00..2415548.85 rows=1237762 width=9) (actual time=75357.455..128531.615 rows=1066667 loops=3) > > Filter: ((MS_CD = '009'::bpchar) AND (ETRYS = '000001'::bpchar)) > > Rows Removed by Filter: 11833442 > > Planning Time: 0.118 ms > > Execution Time: 128668.290 ms > > > The TBL_SHA table has another index, as shown below. > > > CREATE INDEX index_search_02 ON mdb.TBL_SHA USING btree (ET_CD, ETRYS) > > CREATE INDEX index_search_03 ON mdb.TBL_SHA USING btree (MS_CD, ET_DAY, BK_CD, FR_CD, RM_CD) > > Rows Removed by Filter: 11833442 select (38700325 - 11833442) /38700325.0; is 0.69 approx. So I think it says around 69% of rows satisfy the query condition. but I am not sure in the following 2 cases, whether the actual rows are noisy or not. I can not find the doc explaining it. > Partial Aggregate (actual time=128655.256..128655.258 rows=1 loops=3) > Finalize Aggregate (actual time=128667.437..128668.246 rows=1 loops=1)
