RE: Table compression

  • From: "Koivu, Lisa" <Lisa.Koivu@xxxxxxxxxxxxxxx>
  • To: <oracle-l@xxxxxxxxxxxxx>, <lkemnitz@xxxxxxxx>
  • Date: Sat, 20 Mar 2004 06:30:06 -0500

Hi Leroy, 

I use compression.  Beware that adding a column requires uncompressing
the table, adding the column, and re-compressing.   Also, the percentage
of compression you achieve can vary.  If you do not use bulk insert, you
will only receive nominal compression. If you do use bulk, you can get
up to 40-50% compression.  Even then it's not consistent, at least with
the way I use it. .

I do not see my insert times increased with bulk loading and compressed
tables as a target.  Then again I am using pl/sql tables and insert
into.. select from.  The reponse time is reasonable and is still faster
than non-direct.

I don't have any compressed indexes.  I know it's possible, I just never
implemented it.

HTH

Lisa Koivu
Oracle Database Monkey Mama
Orlando, FL, USA

-----Original Message-----
From: LeRoy Kemnitz [mailto:lkemnitz@xxxxxxxx] 
Sent: Friday, March 19, 2004 3:41 PM
To: Oracle List
Subject: Table compression


I am looking into doing some table compression on my warehouse database 
to free up some space on the os.  I am running 9.2.0.4 on Unix 5.1.  The

compression is about 2.5:1 on my tables.  The documentation says the 
bulk insert time will be doubled  but the single inserts, updates, and 
deletes are going to be a wash.  Does anyone use compression?  Are there

any problems you notice in the use of it?     I have also read that the 
table will need to be re-compressed after the bulk inserts.  Any 
alternative ideas about getting this done? 

Thanks in advance,

LeRoy

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