RE: ON DELETE CASCADE causing problems
- From: "Igor Neyman" <ineyman@xxxxxxxxxxxxxx>
- To: <sol.beach@xxxxxxxxx>, "Oracle-L" <oracle-l@xxxxxxxxxxxxx>
- Date: Wed, 9 Jul 2008 15:28:39 -0400
This design is fine.
"on delete cascade" is the right way to do it (instead of doing it
through application code).
As for performance - do you have indexes for your FKs?
Igor
________________________________
From: oracle-l-bounce@xxxxxxxxxxxxx
[mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of sol beach
Sent: Wednesday, July 09, 2008 2:12 PM
To: Oracle-L
Subject: ON DELETE CASCADE causing problems
Oracle V10.2 on RHAS4
I am supporting an custom, inhouse application which has many FKs;
which utilize ON DELETE CASCADE capability.
Typically the database very low (1-3) active sessions.
The following SQL results in the database tying itself into knots.
DELETE FROM USERPROFILE WHERE ORG_ID IN
( Select ont.orgnodeId from OrgNode ont where ont.fullyQualifiedName
like '/SOME/RANDOM/PREFIX/%');
The USERPROFILE table has 3 FK with ON DELETE CASCADE.
Two of these tables have at least 1FK with ON DELETE CASCADE.
These 2 tables have at least 1FK with ON DELETE CASCADE each;
one of which points back to USERPROFILE.
When the DELETE above is invoked, the number of active sessions
soars to 40 & the DELETE took 5239 seconds to complete.
SELECT statements continued to work, but many DML statements
"hung" while this hairball got digested.
Needless to say, folks were not pleased.
Even though I had no part of designed this "capability",
I have been tasked with reducing the impact across the application.
Which VIEW & COLUMN indicates the "ON DELETE CASCADE" exists?
What would be the SQL that reports all tables impacted by the
DELETE statement above?
Any & all suggestions are welcomed.
Thanks In Advance
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