Re: Compressing data in a lob column in Oracle9i

From: Tanel Põder <change_to_my_first_name_at_integrid.info>
Date: Sat, 1 May 2004 14:52:06 +0300
Message-ID: <40938f68_1@news.estpak.ee>

"Prem K Mehrotra" <premmehrotra_at_hotmail.com> wrote in message news:43441e77.0404281816.35e301f9_at_posting.google.com...
> I had read about the compression feature added in Oracle9i, i.e., a
> table can be compressed. However, when I found an application to use
> compression, I was terribly disappointed that Oracle compression does
> not work on LOB data types.

Terribly disappointed?

Where did you read from Oracle9i documentation that it will automatically compress your LOB data? You were disappointed because of your own false assumptions.

Oracle doesn't compress LOBs nor table data with regular compression methods (like zip and similar). The compress clause in create table syntax just allows Oracle to use space more efficiently within a datablock by storing similar values of columns of rows inside a datablock only once.

Btw, if you start compressing & uncompressing inside a database (no matter how), you need really lots of extra CPU there and if you have CPU based licensing, it will get very expensive.

I'd rather leave the (un)compression to application servers...

Tanel. Received on Sat May 01 2004 - 06:52:06 CDT