Re: Compressing data in a lob column in Oracle9i

"Tanel Põder" <change_to_my_first_name_at_integrid.info> wrote in message news:<40938f68_1_at_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.

Thanks a lot for various reponses. Looking at Oracle9i documentation, it seems that various restrictions regarding use of lob inside a trigger have bene removed,
so it should be posisble to do compression inside a trigger and then do uncompress using a view.

Disk space at my site is quite epensive, our server has lots of CPU cycles, so
compression/uncompress should be useful.

Prem Received on Sat May 01 2004 - 19:38:36 CDT