Oracle-L: RE: Partitioning

From: Meng, Dennis <Dennis.Meng_at_cardinal.com>
Date: Tue, 12 Aug 2003 14:24:34 -0800
Message-ID: <F001.005CA546.20030812142434@fatcity.com>

Thanks all who replied. The purpose of this excercise is mainly #1 mentioned in Dennis W.'s e-mail. Because of the size of this table, purging has been a challenge and we want to keep only 2 years data in the table and periodically drop partitions to save space.

Dennis

-----Original Message-----
Sent: Tuesday, August 12, 2003 4:19 PM
To: Multiple recipients of list ORACLE-L

Dennis

What are you trying to achieve by partitioning? Generally I've seen two common goals, 1) break a large table into more manageable pieces, 2) performance tuning, so a query only has to scan a small partition. Sometimes the two can be achieved simultaneously, sometimes they are at odds. If you had a year column, and partitioned on that column, you might have manageability, but if none of your queries included that column, Oracle would probably do a full table scan on all partitions (maybe in parallel if you have the partitions on separate devices). On the other hand, I've partitioned a table by week, which produces 52 partitions for each year. Not good for manageability, but it made the queries blazingly fast.

Dennis Williams
DBA, 80%OCP, 100% DBA
Lifetouch, Inc.
dwilliams_at_lifetouch.com

-----Original Message-----
Sent: Tuesday, August 12, 2003 11:04 AM
To: Multiple recipients of list ORACLE-L

I have worked with partitioning before but have yet encountered the following challenge -
The table we are trying to partition is a large table with hundreds of millions of rows, which is ok. But it does not have a month column, although it has dates. I would like to partition by month because this table contains years of data and partitioning by days will result in thousands of partitions. Of course we can add a month column but I think that will require extensive downtime which we can't afford and I suspect it will cause row-chaining as well. So anybody care to share with me any other options/suggestions?

TIA Dennis

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Author: Meng, Dennis
INET: Dennis.Meng_at_cardinal.com

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RE: Partitioning - followup