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Home -> Community -> Mailing Lists -> Oracle-L -> RE: Table compression
I meant lookup areas in each block.
Waleed
-----Original Message-----
From: Khedr, Waleed
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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