Re: Index compression on Oracle 9.2
- From: "Jonathan Lewis" <jonathan@xxxxxxxxxxxxxxxxxx>
- To: <j.velikanovs@xxxxxxxxx>
- Date: Fri, 3 Feb 2006 11:40:35 -0000
Jurijs,
The pctfree automatically switches to zero on compression,
and any updates require a row to be uncompressed - and
it isn't re-compressed (or rather re-tokenised) after update,
so it's almost guaranteed to become a migrated row.
The critical feature for table compression is that the
table should be made read-only once compressed.
As with so many things Oracle - once you work out WHY
a features exists, it's much easier to see HOW to use it.
Regards
Jonathan Lewis
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----- Original Message -----
From: "Jurijs Velikanovs" <j.velikanovs@xxxxxxxxx>
Cc: "ORACLE-L" <oracle-l@xxxxxxxxxxxxx>
Sent: Friday, February 03, 2006 11:26 AM
Subject: Re: Index compression on Oracle 9.2
Dave, Tanel,
Thank you very much for spotting the areas there the "compressed
table" feature can be used.
It still looks to me usable only for specific (DHW kind) areas.
Audit data is good one :)
I would like to make some testing of the feature in nearest time
(influence on CPU consumption the most interesting question).
I will update list on the results.
BTW: If some body have got results of that kind of testing, please do
not hesitate to share them with the list ;))))
Jurijs
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