Re: Impact of With Clause on Redo Log
From: dombrooks <dombrooks_at_hotmail.com>
Date: Mon, 19 Mar 2012 10:39:04 -0700 (PDT)
Message-ID: <22558287.5524.1332178744764.JavaMail.geo-discussion-forums_at_vbut24>
If, by using the with clause, you end up with a TEMP TABLE TRANSFORMATION/LOAD AS SELECT step and a materialisation of some of the data then behind the scenes you will be creating and/or populating an internal temporary table, the undo for which should generate redo.
Date: Mon, 19 Mar 2012 10:39:04 -0700 (PDT)
Message-ID: <22558287.5524.1332178744764.JavaMail.geo-discussion-forums_at_vbut24>
If, by using the with clause, you end up with a TEMP TABLE TRANSFORMATION/LOAD AS SELECT step and a materialisation of some of the data then behind the scenes you will be creating and/or populating an internal temporary table, the undo for which should generate redo.
Depending on the execution plan, the materialisation of this data might be generating more redo than the previous explicit use of a temp table.
All guesswork without more information.
Cheers,
Dominic
Received on Mon Mar 19 2012 - 12:39:04 CDT