On Thu, 2023-07-20 at 15:09 +0800, gzh wrote: > I'm running into some performance issues with my SQL query. > The following SQL query is taking a long time to execute. > > explain analyze > select COUNT(ET_CD) > from TBL_SHA > WHERE TBL_SHA.MS_CD = '009' > and TBL_SHA.ETRYS in > (select TBL_INF.RY_CD > from TBL_INF > WHERE TBL_INF.MS_CD = '009' > AND TBL_INF.RY_CD = '000001' > ) > ----- 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 = '009'::bpchar) AND (RY_CD = '000001'::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 = '009'::bpchar) AND (ETRYS = '000001'::bpchar)) > Rows Removed by Filter: 32000325 > Planning Time: 0.162 ms > Execution Time: 124168.838 ms > -------------------------------------------------------------------------------- > > The index is defined as follows. > > CREATE INDEX index_search_01 ON mdb.TBL_SHA USING btree (MS_CD, ETRYS); Actual rows = 3200000, rows removed by filter is ten times as much. It should use an index. > When I take the following sql statement, the index works fine and the query is fast. > > select COUNT(ET_CD) > from TBL_SHA > WHERE MS_CD = '009' > AND ETRYS = '000001' > > The amount of data in the table is as follows. > TBL_SHA 38700325 > TBL_INF 35546 This looks very much like it is a problem with the data types. I see that you are using "character", which you shouldn't do. What I cannot see is if the columns are defined as "character" or whether you bind the parameters as "character". Can you show us the table definition of "TBL_SHA" and "TBL_INF"? Yours, Laurenz Albe
