RE: How to speed up an update
- From: <genegurevich@xxxxxxxxxxxx>
- To: "Stephens, Chris" <chris_stephens@xxxxxxxxxxxx>
- Date: Thu, 5 Mar 2009 15:42:06 -0600
Chris,
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"
<chris_stephens@a
dmworld.com> To
<genegurevich@xxxxxxxxxxxx>,
03/05/2009 12:59 <oracle-l@xxxxxxxxxxxxx>
PM cc
Subject
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-----
From: oracle-l-bounce@xxxxxxxxxxxxx
[mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of
genegurevich@xxxxxxxxxxxx
Sent: Thursday, March 05, 2009 12:23 PM
To: oracle-l@xxxxxxxxxxxxx
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 10.2.0.2
thank you
Gene Gurevich
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