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RE: Table compression

From: Goulet, Dick <DGoulet_at_vicr.com>
Date: Fri, 19 Mar 2004 17:39:16 -0500
Message-ID: <4001DEAF7DF9BD498B58B45051FBEA656D82C9@25exch1.vicorpower.vicr.com>


Humm, that's interesting. Anyone have good commenst to make about index compression??

Dick Goulet
Senior Oracle DBA
Oracle Certified 8i DBA

-----Original Message-----

From: Khedr, Waleed [mailto:Waleed.Khedr_at_FMR.COM] Sent: Friday, March 19, 2004 4:05 PM
To: 'oracle-l_at_freelists.org'
Subject: RE: Table compression

Actually reading from compressed tables is faster than reading from non-compressed in systems that don't have their CPU's 100 percent busy.

Since the segment size becomes 30% of the original size, the system requires less IO to read the data.

There is a very little CPU overhead needed to decompress the data.

Compression is done by building lookup tables for repeating values on the block level.

Regards,

Waleed

-----Original Message-----

From: Goulet, Dick [mailto:DGoulet_at_vicr.com] Sent: Friday, March 19, 2004 3:52 PM
To: oracle-l_at_freelists.org
Subject: RE: Table compression

Yeah, but what's the penalty during reads???

Dick Goulet
Senior Oracle DBA
Oracle Certified 8i DBA

-----Original Message-----

From: Khedr, Waleed [mailto:Waleed.Khedr_at_FMR.COM] Sent: Friday, March 19, 2004 3:48 PM
To: 'oracle-l_at_freelists.org'
Subject: RE: Table compression

I use it, works great, 60% savings.

Once the table/partition gets flagged "compress", any direct load will be compressed.

You will get ora-600 if trying to do parallel direct load.

Also can't add a column to a compressed table.

Waleed

-----Original Message-----

From: LeRoy Kemnitz [mailto:lkemnitz_at_uwsa.edu] 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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Received on Fri Mar 19 2004 - 16:35:46 CST

Original text of this message

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