On Fri, 2023-07-21 at 09:43 +0800, gzh wrote: > The definitions of the columns used in SQL are as follows. > > TBL_SHA > > ms_cd character(6) NOT NULL -- PRIMARY KEY > et_cd character(8) > etrys character(8) > > TBL_INF > > ms_cd character(6) NOT NULL -- PRIMARY KEY > ry_cd character(8) NOT NULL -- PRIMARY KEY > > I made some modifications to the data, and I realized that I should not change the length of the data. > The actual data and its corresponding execution plan are shown below. > > explain analyze > select COUNT(ET_CD) > from TBL_SHA > WHERE TBL_SHA.MS_CD = 'MLD009' > and TBL_SHA.ETRYS in > (select TBL_INF.RY_CD > from TBL_INF > WHERE TBL_INF.MS_CD = 'MLD009' > AND TBL_INF.RY_CD = '00000001' > ) > ----- Execution Plan ----- > Limit (cost=2738709.57..2738709.58 rows=1 width=8) (actual time=124168.769..124168.771 rows=1 loops=1) > -> Aggregate (cost=2738709.57..2738709.58 rows=1 width=8) (actual time=124168.767..124168.769 rows=1 loops=1) > -> Nested Loop (cost=0.29..2730702.63 rows=3202774 width=9) (actual time=97264.166..123920.769 rows=3200000 loops=1) > -> Index Only Scan using TBL_INF_pkc on TBL_INF (cost=0.29..8.31 rows=1 width=9) (actual time=0.025..0.030 rows=1 loops=1) > Index Cond: ((MS_CD = 'MLD009'::bpchar) AND (RY_CD = '00000001'::bpchar)) > Heap Fetches: 1 > -> Seq Scan on TBL_SHA (cost=0.00..2698666.58 rows=3202774 width=18) (actual time=97264.138..123554.792 rows=3200000 loops=1) > Filter: ((MS_CD = 'MLD009'::bpchar) AND (ETRYS = '00000001'::bpchar)) > Rows Removed by Filter: 32000325 > Planning Time: 0.162 ms > Execution Time: 124168.838 ms Thanks. That should definitely use a b-tree index defined on (ms_cd, etrsys). Did you change any parameters that have an impact on query planning? You can see that in the output of EXPLAIN (ANALYZE, BUFFERS, SETTINGS). Yours, Laurenz Albe
