Hi everyone,
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);
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
Any suggestions for improving the performance of the query would be greatly appreciated.
Thanks in advance!