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Update vs CTAS [message #199865]

Thu, 26 October 2006 08:31

a_developer
Messages: 194
Registered: January 2006

Senior Member

I have to update 46M rows of a table which has 219M rows. Is it better to update it or just recreate? Recreating using CTAS (then table renaming) should be fine, but I have to recreate the indexes also.. and I have 12 indexes (9 bitmap and 3 b-tree)?? Any suggestion before I begin my tedious testing.?? Thanks!

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Re: Update vs CTAS [message #199879 is a reply to message #199865]

Thu, 26 October 2006 09:44

Mahesh Rajendran
Messages: 10708
Registered: March 2002
Location: oracleDocoVille

Senior Member
Account Moderator

We are having too many discussions around the same topic recently Smile

.
http://asktom.oracle.com/pls/ask/f?p=4950:8:::NO::F4950_P8_DISPLAYID:6407993912330

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Re: Update vs CTAS [message #199884 is a reply to message #199879]

Thu, 26 October 2006 10:02

Kevin Meade
Messages: 2103
Registered: December 1999
Location: Connecticut USA

Senior Member

a couple of things to keep in mind:

1) make sure you have enough space for a second copy. If you have to keep the old table in place till the new one is ready, then you need to essentially have enough disk space for two copies of the table and each index. This may sound obvious but so many people don't check.

2) along the same lines, make sure you have sufficient sort area space in memory if possible. Index creation will take much less time if it can all be done in memory.

Good luck, Kevin

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