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
At 2023-07-20 22:48:19, "Laurenz Albe" <laurenz.albe@cybertec.at> wrote:
>On Thu, 2023-07-20 at 22:14 +0800, gzh wrote:
>> The information I provided is incorrect, please see my previous reply.
>
>My question remains: I would like to see the table definitions.
>
>Also, did you ANALYZE the tables?
>
>Yours,
>Laurenz Albe