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RE: Index Rebuilds

From: LoughMiller, Gregory <>
Date: Fri, 9 Jun 2000 09:26:37 -0400
Message-Id: <>

we have ran in cost based mode since the beginning(723,734,806, and 815)

We analyze ALL objects once a week. We perform this on a Sunday evening to run most of the evening and thru the Monday early AM hours.. It's the least offensive time in our shop to run this. We will typically perform a compute on most of the objects. But on some of the objects-we will use "estimate" due to their size or processing at that time of day. We have found on the large objects that the estimate of 20% is really accurate when we compared the results to a "compute"..

But whenever you rebuild a table, rebuild the indexes--perform an analyze.. We bit the big one a couple of times by forgetting to run the analyze. We would start digging into performance problems-see full table scans.. And it would hit us-NO STATS!

We got in the habit of running the analyze 1x/week, and storing the results in a secondary table afterwards. We would use that data to trend objects for capacity planning, inconsistencies(1 week-10k rows, the next week 1k, etc..), and tuning..

But I would run a test of your environment with the applications where there are no stats on the objects. And repeat the test after you have analyzed all of the objects.. I have seen some environments where RULE base worked better...


-----Original Message-----
From: cyril [] Sent: Friday, June 09, 2000 9:25 AM
To: Multiple recipients of list ORACLE-L Subject: Re: Index Rebuilds


 I am 'really surprised' that the solution 'commonly' provided for 'such problems' is analyze the table..

 Do people really analyze tables? ( I mean do u get so much down time! if not how do u manage it!)
 Do people really run their applications in COST BASED mode...  cos our organisation has been using Oracle6 onwards and since then the applications have been tuned
 for rule based and recently we tried to move to COST BASED and since all the programs gave a huge problem
 we cried off...

 Has anyone gone from RULE BASED to COST BASED.. can u help!

Author: cyril

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Received on Fri Jun 09 2000 - 08:26:37 CDT

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