RE: query performance - getting started

  • From: "Jorgensen, Finn" <Finn.Jorgensen@xxxxxxxxxxxxxxxxx>
  • To: "'Joel.Patterson@xxxxxxxxxxx'" <Joel.Patterson@xxxxxxxxxxx>, "'oracle-l@xxxxxxxxxxxxx'" <oracle-l@xxxxxxxxxxxxx>
  • Date: Thu, 7 Apr 2011 13:47:47 -0400

Last time I looked into MV refreshes (in 10gR2) they did not do truncates. They 
do a delete of all rows. I assume this is so running queries aren't interrupted 
by the refresh.

So, if you have the luxury of doing a truncate and then insert (append) or 
better yet, drop table and CTAS, and the table is large, then that would be 
faster.

Thanks,
Finn

From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx] On 
Behalf Of Joel.Patterson@xxxxxxxxxxx
Sent: Thursday, April 07, 2011 8:51 AM
To: Joel.Patterson@xxxxxxxxxxx; oracle-l@xxxxxxxxxxxxx
Cc: kylelf@xxxxxxxxx
Subject: RE: query performance - getting started


Query performance continued.

We have a very complicated Materialized view, and a view that utilizes the MV.  
 We cannot use Fast refresh - a complete refresh is necessary.   The app can 
decide when the view is refreshed, and can execute dbms_refresh when necessary.

Essentially all records are truncated, and the view is rebuilt as part of the 
complete refresh.    So, is this just as easy, efficient as any other method 
such as Temp tables, Truncating a permanent table and re-inserting, or other?


Moving forward,

JP

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