Oracle-L: RE: Oracle Compress Option

From: Jamadagni, Rajendra <Rajendra.Jamadagni_at_espn.com>
Date: Thu, 25 Sep 2003 07:19:40 -0800
Message-ID: <F001.005D10C9.20030925071940@fatcity.com>

we have 2 gbit private interconnects of which only one is used at any given time. Everyone else talks to the dbs using public network. Both are active/active. On one instance luckily we have application partitioning one side manages the feeds that come from every foot/bast/basketball, hockey and scores of other games and processes them and sends it out to customers. Another side takes this data plus people sitting to make corrections if any before it is fed to video generators and goes on espn network broadcast. So it works fine.

Other instances are legacy ... the active/active is more like a HA configuration, lots of people connected on either side all the time lots of DML activity going around all the time. We see more of a GC traffic ... but we are experimenting with _fairness_threshold parameter to see if that will help. As for performance issues, we encounter lots of BBW but unfortunately that is due to business logic and can't be easily changed.

Otherwise we do fine.
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-----
Sent: Thursday, September 25, 2003 10:35 AM To: Multiple recipients of list ORACLE-L

Hm, interesting...

How does your active-active config work, do you have write activity on all nodes?
I'd be interested in any performance issues you had or currently have... Have you partitioned your application or data usage somehow? What kind of interconnect you're using?

Tanel.

Original Message ----- To: Multiple recipients of list ORACLE-L <mailto:ORACLE-L_at_fatcity.com> Sent: Thursday, September 25, 2003 4:49 PM

Waleed, I get your point ...

We have 6 RAC instances that run active-active ... and compared to availability requirements, we (incl management) decided that disk is cheap.

I guess it is relative ...

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-----
Sent: Thursday, September 25, 2003 9:35 AM To: Multiple recipients of list ORACLE-L

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-----
Sent: Thursday, September 25, 2003 9:05 AM To: Multiple recipients of list ORACLE-L

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-----
Sent: Wednesday, September 24, 2003 10:05 PM To: Multiple recipients of list ORACLE-L

"Compress to impress?" by Julian Dyke is a good presentation on this topic (see for instance http://www.ukoug.org/calendar/jan03/jan30ab.htm <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: Jamadagni, Rajendra
  INET: Rajendra.Jamadagni_at_espn.com

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Received on Thu Sep 25 2003 - 10:19:40 CDT