RE: Oracle Compress Option

[Khedr, Waleed]

Title: 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:

 

1) 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.

 

2) 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:[EMAIL PROTECTED]
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
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Rajendra dot Jamadagni at nospamespn dot com
All Views expressed in this email are strictly personal.
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-----Original Message-----
From: Mogens Nørgaard [mailto:[EMAIL PROTECTED]]
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

[EMAIL PROTECTED] 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