RE: How to speed up an update

From: <>
Date: Thu, 5 Mar 2009 15:42:06 -0600
Message-ID: <>


I want to do it as fast as possible and yes the column being modified is part of the primary key. CTAS would
be my preferred approach, but I am not able to do it. I did get a good result after I dropped the index.

thank you

Gene Gurevich

             "Stephens, Chris"                                             
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             03/05/2009 12:59          <>            
             PM                                                         cc 
                                       RE: How to speed up an update       

Are you wanting this to run as fastest possible or would you like other operations to be capable of getting on the cpu while doing this?

Is the column you are updating the primary key? If not, why would dropping the pk make a difference?

If there are very few columns (I guess more specifically bytes other than the bytes affected by the update) and you are updating each row as indicated by the vague update statement, you may be better off with ctas + drop original table + rename existing table.

Hopefully you have a test system to verify which option is more efficient.

-----Original Message-----

[] On Behalf Of
Sent: Thursday, March 05, 2009 12:23 PM
Subject: How to speed up an update

Hi everyone:

I am trying to tune the following update:

update TABLE set column = decode (column, vlaue1..);

The TABLE has about 13mil rows and a primary key. I am thinking of dropping
the PK and running the update
with higher degree of parallelism and rebuilding the PK after the update.
Is there anything else I should consider? I am running oracle

thank you

Gene Gurevich

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-- Received on Thu Mar 05 2009 - 15:42:06 CST

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