Re: Index compression on Oracle 9.2

> plus there'll be obvious CPU usage because it'll need to uncompress for
> every read and compress for every write. The few GBs of storage to be saved
I wouldn't say that CPU usage increasing is so obvious. Oracle actually doesn't do any compression
(oracle always toyed to avoid compression algorithms usage as Zip and other classical utilities are using).
In an "Index compression" feature case Oracle avoids duplicate records in leaf blocks. I would call the feature differently than Oracle did, because the name doesn't reflect the meaning of functionality.

By my opinion the feature is absolutely grate (whilst table compression is rubbish). If you are using it in right place it will not just save you a space on disk but reduce pressure on Memory and CPU. We have used it with grate success in different projects.

I would recommend you to test it on your test database. Then you would get an impression how many memory it will save you.

Jurijs
On 1/31/06, Jesse, Rich <Rich.Jesse_at_quadtechworld.com> wrote:
>
> Read up on MetaLink about it. I had looked into it too for some GB indexes,
> but I seem to remember that most/all of the ONLINE options no longer work,
> plus there'll be obvious CPU usage because it'll need to uncompress for
> every read and compress for every write. The few GBs of storage to be saved
> (in our case, a max of 1 GB) wasn't worth the hassle to me. YMMV
>
> GL!
>
> Rich
>
>
>
> -----Original Message-----
> From: oracle-l-bounce_at_freelists.org [mailto:oracle-l-bounce_at_freelists.org]
> On Behalf Of Luc Demanche
> Sent: Tuesday, January 31, 2006 9:15 AM
> To: oracle-l_at_freelists.org
> Subject: Index compression on Oracle 9.2
>
>
> Hi,
>
> Oracle 9.2
>
> We are looking to use the index compression.
> We have a table of 18Gigs of data, contening 42 millions of rows.
>
> One of the index is 19Gig, another one 17 Gigs, and so on ....
>
> We are looking to reduce the space used by the indexes, but all of the
> indexes are important.
>
> Will the compression on the indexes will help us ? Do you have good/bad
> stories about that.
>
> Thanks
> Luc
>
>
>
> --
> Luc Demanche
> Oracle DBA
> (514) 867-9977

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Jurijs
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