RE: performance when inserting into child tables

From: Justin Cave (DDBC) <jcave_at_ddbcinc.com>
Date: Wed, 21 Apr 2004 12:55:38 -0600
Message-ID: <87E9F113CEF1D211A4C30090273018741BBCBC@ddbcinc.ddbc.local>

Tom Kyte has a couple of discussions on the mechanics of the 9i change. One such discussion:
http://asktom.oracle.com/pls/ask/f?p=3D4950:8:::::F4950_P8_DISPLAYID:2920= 1
6138754#12042176336306=20

Justin Cave
Distributed Database Consulting, Inc.
http://www.ddbcinc.com/askDDBC

-----Original Message-----
From: oracle-l-bounce_at_freelists.org
[mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Mladen Gogala Sent: Wednesday, April 21, 2004 12:45 PM To: oracle-l_at_freelists.org
Subject: Re: performance when inserting into child tables

Lock is released before commit? That would be something! So, what is to prevent child from inserting a record with an old value of the foreign key, the only one that it can see? It looks like a slight violation of the ACID property. What, exactly, do they mean by "immediately"? If it is "immediately after the transaction ends", then it's not so new. If the lock is released before the transaction modifying the parent key ends, there are quite few nasty possibilities for breaking the integrity. Do you have any Metalink note? Was the instructor a former second hand car salesman or a real estate agent?

On 04/21/2004 02:22:51 PM, "Mercadante, Thomas F" wrote:
> Jared, =20

>=20

> you said:

>=20

> "The lack of indexes for the FK's will cause a share lock to be taken=20
> out on the child table when ever the parent is deleted or updated."
>=20
> The most recent Oracle class I took said that in 9i, this lock on the
child
> table is taken and released immediately. Supposedly to speed the
process up
> a bit.

--=20
Mladen Gogala
Oracle DBA

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Received on Wed Apr 21 2004 - 13:49:33 CDT