Is it correct to say that the full outer join logic implementation just
can't be rewritten to make it any better path. And then it looks like usage
of full outer join is riskier.
So the only way would be make available required amount of memory so that
temp/disk read won't impact the run time. Or else ensure same amount of
rows to persist on the base table all the time and not let them grow
overtime , so that the hash join will happen fully in memory?
On Thu, 24 Dec 2020, 9:14 pm Lok P, <loknath.73@xxxxxxxxx> wrote:
Attached is the sql monitor with Right Outer join path. And I do see the
estimation of plan_line_id- 3 is deviating by a large number.
But the issue , i see is the number of rows does match with the original
one, but i see the values getting mismatched, some of the columns are
coming as null in the modified query whereas those are having not null
values in the original query result for those three rows. And also the
total execution time is close to ~5minutes .
On Thu, Dec 24, 2020 at 8:24 PM Sayan Malakshinov <xt.and.r@xxxxxxxxx>
wrote:
Also you need to help CBO with predicates like this:
SELECT ....~58 columns projected...
FROM (SELECT ....~60 columns projected
FROM "USER1"."BOS" "A2"
RIGHT OUTER JOIN
(SELECT ...~41 columns projected from A4 and A5
FROM "USER1"."CS" "A4"
RIGHT OUTER JOIN "USER1"."COX" "A5"
ON "A5"."EID" = "A4"."EID"
-- added a copy of the predicates:
where
"A5"."BI0" = :b1
OR "A5"."BI0" IS NOT NULL AND "A5"."CT1" = 'XXX'
OR "A5"."BI0" IS NULL AND "A5"."CT1" = 'YYY'
-- end
) "A3"
ON "A2"."BI" = "A3"."BID1"
AND "A2"."OID" = TO_NUMBER ("A3"."OID2")) "A1"
WHERE "COX"."BI0" = :b1
OR "BOS"."COl1" = :b2
AND "BOS"."I_DT" IS NULL
AND ( "COX"."BI0" IS NOT NULL
AND "COX"."CT1" = 'XXX'
OR "COX"."BI0" IS NULL AND "COX"."CT1" = 'YYY')
On Thu, Dec 24, 2020 at 5:46 PM Sayan Malakshinov <xt.and.r@xxxxxxxxx>
wrote:
Ok, I see the problem, you just need to replace both left joins to
'right join', because as I said previously, all rows of the final resultset
should contain rows from COX.
Best regards,
Sayan Malakshinov
Oracle performance tuning expert
Oracle Database Developer Choice Award winner
Oracle ACE Associate
http://orasql.org
чт, 24 дек. 2020 г., 17:43 Lok P <loknath.73@xxxxxxxxx>:
I have just simply , replaced the FULL OUTER join with LEFT OUTER Join
, something as below(with actual aliases) and ran it.
I am sensing like, i did something wrong , and not the way which you
thought of perhaps. Can you guide me here please, how you want me to test
it.
SELECT ....~58 columns projected...
FROM (SELECT ....~60 columns projected
FROM "USER1"."BOS" "A2"
*LEFT OUTER JOIN*
(SELECT ...~41 columns projected from A4 and A5
FROM "USER1"."CS" "A4"
*LEFT OUTER JOIN* "USER1"."COX" "A5"
ON "A5"."EID" = "A4"."EID") "A3"
ON "A2"."BI" = "A3"."BID1"
AND "A2"."OID" = TO_NUMBER ("A3"."OID2")) "A1"
WHERE "COX"."BI0" = :b1
OR "BOS"."COl1" = :b2
AND "BOS"."I_DT" IS NULL
AND ( "COX"."BI0" IS NOT NULL
AND "COX"."CT1" = 'XXX'
OR "COX"."BI0" IS NULL AND "COX"."CT1" = 'YYY')
On Thu, Dec 24, 2020 at 8:03 PM Sayan Malakshinov <xt.and.r@xxxxxxxxx>
wrote:
Can you show both original and modified queries?
--
Best regards,
Sayan Malakshinov
Oracle performance tuning engineer
Oracle ACE Associate
http://orasql.org
