Re: Is there any good optimization solution to improve the query efficiency?

Thank you very much for taking the time to reply to my question.

I followed your suggestion and rewrote the SQL using Common Table Expression (CTE).

Unfortunately, there was no significant improvement in performance.

At 2023-06-05 17:47:25, "Lorusso Domenico" <domenico(dot)l76(at)gmail(dot)com> wrote:

Hello,
In many case a formal writing and usage of with statement could solve the issue.
If you need join, use always join:
where T_POV2.RSNO = T_CUST.RSNO
and T_POV2.KNO = T_CUST.KNO
and T_POV2.GSTSEQ = T_CUST.GSTSEQ)

this is an inner join.

I mean something like this
with t_pov2 as (
select T_CUST.RSNO ,
T_CUST.KNO ,
MIN(T_CUST.GSTSEQ) GSTSEQ
from TBL_CUST T_CUST ,
TBL_POV T_POV ,
TBL_RES T_RES
where T_CUST.STSFLG = 'T'
and T_CUST.DISPSEQ <> 9999
AND T_CUST.KFIX = '0'
and T_POV.CRSNO = T_RES.CRSNO
and T_RES.RSNO = T_CUST.RSNO
group by T_CUST.RSNO , T_CUST.KNO
), t_pov3 as (
select T_CUST.RSNO RSNO2 ,
T_CUST.KNO ,
T_CUST.AGE ,
T_CUST.GST
from TBL_CUST T_CUST
inner join t_pov2 on T_POV2.RSNO = T_CUST.RSNO
and T_POV2.KNO = T_CUST.KNO
and T_POV2.GSTSEQ = T_CUST.GSTSEQ
)

select *
from TBL_RES
left outer join t_pov3 on TBL_RES.RSNO = T_POV3.RSNO2
and TBL_RES.KNO = T_POV3.KNO
where TBL_RES.CID >= to_date('2022/07/01', 'YYYY/MM/DD')
and TBL_RES.CID <= to_date('2022/07/31', 'YYYY/MM/DD')
and TBL_RES.COD >= to_date('2022/07/01', 'YYYY/MM/DD')
and TBL_RES.COD <= to_date('2022/07/31', 'YYYY/MM/DD')

but if tbl_res contain lessere record a good idea is start from this table and use in join with other

Il giorno lun 5 giu 2023 alle ore 08:57 gzh <gzhcoder(at)126(dot)com> ha scritto:

Hi everyone,

I'm running into some performance issues with my SQL query.
The following SQL query is taking a long time to execute.

Execution Plan：
explain analyse
select * from TBL_RES
left outer join(select T_CUST.RSNO RSNO2 ,
T_CUST.KNO ,
T_CUST.AGE ,
T_CUST.GST
from TBL_CUST T_CUST ,
(select T_CUST.RSNO ,
T_CUST.KNO ,
MIN(T_CUST.GSTSEQ) GSTSEQ
from TBL_CUST T_CUST ,
TBL_POV T_POV ,
TBL_RES T_RES
where T_CUST.STSFLG = 'T'
and T_CUST.DISPSEQ <> 9999
AND T_CUST.KFIX = '0'
and T_POV.CRSNO = T_RES.CRSNO
and T_RES.RSNO = T_CUST.RSNO
group by T_CUST.RSNO , T_CUST.KNO) T_POV2
where T_POV2.RSNO = T_CUST.RSNO
and T_POV2.KNO = T_CUST.KNO
and T_POV2.GSTSEQ = T_CUST.GSTSEQ) T_POV3 on TBL_RES.RSNO = T_POV3.RSNO2
and TBL_RES.KNO = T_POV3.KNO
where TBL_RES.CID >= to_date('2022/07/01', 'YYYY/MM/DD')
and TBL_RES.CID <= to_date('2022/07/31', 'YYYY/MM/DD')
and TBL_RES.COD >= to_date('2022/07/01', 'YYYY/MM/DD')
and TBL_RES.COD <= to_date('2022/07/31', 'YYYY/MM/DD')
----- Execution Plan -----
Nested Loop Left Join (cost=254388.44..452544.70 rows=473 width=3545) (actual time=3077.312..996048.714 rows=15123 loops=1)
Join Filter: ((TBL_RES.RSNO = T_CUST.RSNO) AND ((TBL_RES.KNO)::text = (T_CUST.KNO)::text))
Rows Removed by Join Filter: 4992268642
-> Gather (cost=1000.00..58424.35 rows=473 width=3489) (actual time=0.684..14.158 rows=15123 loops=1)
Workers Planned: 2
Workers Launched: 2
-> Parallel Seq Scan on TBL_RES (cost=0.00..57377.05 rows=197 width=3489) (actual time=0.096..279.504 rows=5041 loops=3)
Filter: ((CID >= to_date('2022/07/01'::text, 'YYYY/MM/DD'::text)) AND (CID <= to_date('2022/07/31'::text, 'YYYY/MM/DD'::text)) AND (COD >= to_date('2022/07/01'::text, 'YYYY/MM/DD'::text)) AND (COD <= to_date('2022/07/31'::text, 'YYYY/MM/DD'::text)))
Rows Removed by Filter: 161714
-> Materialize (cost=253388.44..394112.08 rows=1 width=56) (actual time=0.081..26.426 rows=330111 loops=15123)
-> Hash Join (cost=253388.44..394112.07 rows=1 width=56) (actual time=1197.484..2954.084 rows=330111 loops=1)
Hash Cond: ((T_CUST.RSNO = T_CUST_1.RSNO) AND ((T_CUST.KNO)::text = (T_CUST_1.KNO)::text) AND (T_CUST.gstseq = (min(T_CUST_1.gstseq))))
-> Seq Scan on TBL_CUST T_CUST (cost=0.00..79431.15 rows=2000315 width=61) (actual time=0.015..561.005 rows=2000752 loops=1)
-> Hash (cost=246230.90..246230.90 rows=262488 width=50) (actual time=1197.025..1209.957 rows=330111 loops=1)
Buckets: 65536 Batches: 8 Memory Usage: 2773kB
-> Finalize GroupAggregate (cost=205244.84..243606.02 rows=262488 width=50) (actual time=788.552..1116.074 rows=330111 loops=1)
Group Key: T_CUST_1.RSNO, T_CUST_1.KNO
-> Gather Merge (cost=205244.84..238964.80 rows=268846 width=50) (actual time=788.547..982.479 rows=330111 loops=1)
Workers Planned: 2
Workers Launched: 1
-> Partial GroupAggregate (cost=204244.81..206933.27 rows=134423 width=50) (actual time=784.032..900.979 rows=165056 loops=2)
Group Key: T_CUST_1.RSNO, T_CUST_1.KNO
-> Sort (cost=204244.81..204580.87 rows=134423 width=23) (actual time=784.019..833.791 rows=165061 loops=2)
Sort Key: T_CUST_1.RSNO, T_CUST_1.KNO
Sort Method: external merge Disk: 5480kB
Worker 0: Sort Method: external merge Disk: 5520kB
-> Parallel Hash Join (cost=111758.80..190036.38 rows=134423 width=23) (actual time=645.302..716.247 rows=165061 loops=2)
Hash Cond: (T_CUST_1.RSNO = T_RES.RSNO)
-> Parallel Seq Scan on TBL_CUST T_CUST_1 (cost=0.00..74013.63 rows=204760 width=23) (actual time=0.018..264.390 rows=165058 loops=2)
Filter: ((dispseq <> '9999'::numeric) AND ((stsflg)::text = 'T'::text) AND ((KFIX)::text = '0'::text))
Rows Removed by Filter: 835318
-> Parallel Hash (cost=109508.52..109508.52 rows=137142 width=8) (actual time=343.593..343.896 rows=165058 loops=2)
Buckets: 131072 Batches: 8 Memory Usage: 3008kB
-> Parallel Hash Join (cost=51834.70..109508.52 rows=137142 width=8) (actual time=256.732..314.368 rows=165058 loops=2)
Hash Cond: ((T_RES.crsno)::text = (T_POV.crsno)::text)
-> Parallel Seq Scan on TBL_RES T_RES (cost=0.00..53199.02 rows=208902 width=17) (actual time=0.007..100.510 rows=250132 loops=2)
-> Parallel Hash (cost=49450.42..49450.42 rows=137142 width=9) (actual time=122.308..122.309 rows=165054 loops=2)
Buckets: 131072 Batches: 8 Memory Usage: 2976kB
-> Parallel Seq Scan on TBL_POV T_POV (cost=0.00..49450.42 rows=137142 width=9) (actual time=0.037..89.470 rows=165054 loops=2)
Planning Time: 1.064 ms
Execution Time: 996062.382 ms
--------------------------------------------------------------------------------

The amount of data in the table is as follows.
TBL_RES 500265
TBL_CUST 2000752
TBL_POV 330109

Any suggestions for improving the performance of the query would be greatly appreciated.

Thanks in advance!

--

Domenico L.

per stupire mezz'ora basta un libro di storia,
io cercai di imparare la Treccani a memoria... [F.d.A.]