Oracle-L: Re: Oracle Compress Option

From: Tanel Poder <tanel.poder.003_at_mail.ee>
Date: Thu, 25 Sep 2003 06:49:47 -0800
Message-ID: <F001.005D10C5.20030925064947@fatcity.com>

RE: Oracle Compress OptionHi!

I think in DW style environments, compressed fact tables and indexes on them can give more benefit than just saved disk storage -> if you save 50% in space due compression, then 100% more data can be read in single IO as well.

Tanel.

Original Message ----- From: Khedr, Waleed To: Multiple recipients of list ORACLE-L Sent: Thursday, September 25, 2003 4:34 PM Subject: RE: Oracle Compress Option

Disk is not cheap if you pay for high availability configuration. I compress historical data on daily basis and was able to save 70 percent of the disk space. Imagine the amount of savings for five TB.

Two major issues:

Oracle says updates will be slow on compressed tables, but I say don't even try to update a compressed table, uncompress first otherwise you will end up with a segment that is not good at all for scattered reads.
You can not add columns to the table when it's compressed, so if you compressed a big table and need a new column you need to recreate the table without compression. So adding many extra columns before compression is a good idea.

It's mainly good for data warehouses applications.

Regards,

Waleed

-----Original Message-----
From: Jamadagni, Rajendra [mailto:Rajendra.Jamadagni_at_espn.com] Sent: Thursday, September 25, 2003 9:05 AM To: Multiple recipients of list ORACLE-L Subject: RE: Oracle Compress Option

I think 9202 doesn't like to export compressed tables in direct mode .. so watch out for that ... I implemented, tested and next day reverted back to regular tables due to this export issue. Disk is cheap.

A BAARF party member wannabe !!
Raj

Rajendra dot Jamadagni at nospamespn dot com All Views expressed in this email are strictly personal. QOTD: Any clod can have facts, having an opinion is an art !

-----Original Message-----
From: Mogens Nørgaard [mailto:mln_at_miracleas.dk] Sent: Wednesday, September 24, 2003 10:05 PM To: Multiple recipients of list ORACLE-L Subject: Re: Oracle Compress Option

"Compress to impress?" by Julian Dyke is a good presentation on this topic (see for instance http://www.ukoug.org/calendar/jan03/jan30ab.htm).

I do have the article - 202 K with no compression, 147 K with compression :).

Let me know if you're interested, and I'll email it directly to you.

Mogens

Avnish.Rastogi_at_providence.org wrote:

>Does anybody has any experience with Oracle 9I compression option. I did some test on 9202 with a table of more 14 million rows. Table has total 7 indexes. Surprising both table and indexes are using more space after compression. Before compression space used is 13064MB and after compression 13184MB. In both the cases I did export from source table and stored in two different tablespaces. Any insight on that and any disadvantages of using that.

>
>Thanks

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Author: Tanel Poder
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Received on Thu Sep 25 2003 - 09:49:47 CDT