Query Performance Issue
Date: Wed, 3 Nov 2021 00:48:15 +0530
Message-ID: <CAEjw_fiKr6uC6DHyNLwptnnyDTpdF1Jd1yJmC=J1HejW_Ca9JA_at_mail.gmail.com>
Hi , It's an oracle 19C database. We have the below query which runs ~7-10seconds per execution and we want to see if we can further make the improvement in run time someway. it's called thousands of times in a process because of certain design limitations of a third party app, so the number of executions can't be minimized to once per process. So we are trying to see what we can do to minimize the run time per execution for this query.
As per ASH the major amount of time spent in plan_line_id 12 and 13 i.e. scanning of table RFCER. And in sql monitor that shows ~4K+ executions for that line and its matching with the number of rows in table RTNI. Then the second highest time is spent on plan_line_id 14 and 15 which shows ~1million execution. Here table RTNI is a global temporary table which is populated during run time. So want to understand what we can do to improve the run time for this query?
SELECT RDC.SCD, RDC.SCDSC , RDC.DCC, RDC.DCDSC , ERATE FROM RFCER ,
( SELECT DISTINCT RDCH.CKEY
FROM RTNI , RDCH
WHERE TO_CHAR (RTNI.MCI) = RDCH.CID
AND RDCH.CT_CD = 'XX') RTNI,
RDC
WHERE RFCER.CKEY = RTNI.CKEY
AND RFCER.AFRI = 'ZZZZ'
AND CLKEY = 20211001
AND RFCER.CR_KEY = RDC.CR_KEY
AND RDC.SCD || '/' || RDC.DCC = 'AAAAAA';
Thinking if converting the Distinct inline query using below EXISTS operator will help anyway?
(SELECT RDCH.CKEY
FROM RDCH RDCH
WHERE RDCH.CT_CD = 'XX'
AND EXISTS
(SELECT 'X'
FROM RTNI RTNI
WHERE TO_CHAR (RTNI.MCI) = RDCH.CID)) RTNI
Global Information
Status : DONE (ALL ROWS) Instance ID : 2 SQL ID : 3dfmkcu292v30 SQL Execution ID : 33555042 Execution Started : 11/01/2021 22:11:49 First Refresh Time : 11/01/2021 22:11:55 Last Refresh Time : 11/01/2021 22:11:56 Duration : 7s Fetch Calls : 1
Global Stats
| Elapsed | Cpu | Other | Fetch | Buffer |
| Time(s) | Time(s) | Waits(s) | Calls | Gets |
| 6.95 | 6.85 | 0.10 | 1 | 3M |
SQL Plan Monitoring Details (Plan Hash Value=3330725745)
| Id | Operation | Name
| Rows | Cost | Time | Start | Execs | Rows | Mem |
Activity | Activity Detail |
| | |
| (Estim) | | Active(s) | Active | | (Actual) | (Max) | (%) | (# samples) |
| 0 | SELECT STATEMENT |
| | | | | 1 | | . |
| |
| 1 | VIEW | VM_NWVW_1
| 3 | 7616 | | | 1 | | . |
| |
| 2 | HASH UNIQUE |
| 3 | 7616 | | | 1 | | . |
| |
| 3 | NESTED LOOPS |
| 3 | 7615 | 2 | +6 | 1 | 0 | . |
| |
| 4 | NESTED LOOPS |
| 3 | 7615 | 2 | +6 | 1 | 1M | . |
| |
| 5 | NESTED LOOPS |
| 3 | 7612 | 2 | +6 | 1 | 1M | . |
| |
| 6 | HASH JOIN |
| 2080 | 3437 | 2 | +6 | 1 | 4007 | 3MB |
| |
| 7 | TABLE ACCESS STORAGE FULL | RTNI
| 4335 | 30 | 1 | +6 | 1 | 4007 | . |
| |
| 8 | VIEW | index$_join$_004
| 234K | 3406 | 2 | +6 | 1 | 50883 | . |
| |
| 9 | HASH JOIN |
| | | 2 | +6 | 1 | 50883 | 7MB |
| |
| 10 | INDEX RANGE SCAN | RDCH_IX1
| 234K | 857 | 1 | +6 | 1 | 50883 | . |
| |
| 11 | INDEX STORAGE FAST FULL SCAN | RDCH_PK
| 234K | 1779 | 2 | +6 | 1 | 702K | . |
| |
| 12 | TABLE ACCESS BY INDEX ROWID BATCHED | RFCER
| 1 | 6 | 5 | +3 | 4007 | 1M | . |
| |
| 13 | INDEX RANGE SCAN | RFCER_IX2
| 7 | 2 | 4 | +4 | 4007 | 1M | . |
| |
| 14 | INDEX UNIQUE SCAN | RDC_PK
| 1 | | 6 | +2 | 1M | 1M | . |
| |
| 15 | TABLE ACCESS BY INDEX ROWID | RDC
| 1 | 1 | 1 | +1 | 1M | 0 | . |
| |
==================================================================================================================================================================================
Predicate Information (identified by operation id):
6 - access("RDCH"."CID"=TO_CHAR("RTNI"."MCI"))
8 - filter("RDCH"."CT_CD"='XX')
9 - access(ROWID=ROWID)
10 - access("RDCH"."CT_CD"='XX')
12 - filter("RFCER"."AFRI"='ZZZZ')
13 - access("RFCER"."CKEY"="RDCH"."CKEY" AND "CLKEY"=20211001)
14 - access("RFCER"."CR_KEY"="RDC"."CR_KEY")
15 - filter("RDC"."SCD"||'/'||"RDC"."DCC"='AAAAAA')
-- http://www.freelists.org/webpage/oracle-lReceived on Tue Nov 02 2021 - 20:18:15 CET