Thank you for your reply. The information I provided is incorrect, please see my previous reply.
>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"? For information security reasons, I can't provide the table definition, these columns are defined as "character". At 2023-07-20 19:58:59, "Laurenz Albe" <laurenz.a...@cybertec.at> wrote: >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
