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RE: Checking the rebuildability of an index

From: <Jared.Still_at_radisys.com>
Date: Tue, 06 Aug 2002 14:53:33 -0800
Message-ID: <F001.004ACDCD.20020806145333@fatcity.com>


The TK article mentions using metrics over time to determine if you are going to rebuild an index.

There are several things required to do so effectively

Oracle does not give the DBA these kind of metrics, they aren't available from the database. There are some third party tools that may give you this data, but they're expensive to buy, expensive to implement.

It's much easier to identify possible candidates for rebuilding, then rebuild them.

Jared

"Post, Ethan" <Ethan.Post_at_ps.net>
08/06/2002 01:55 PM  

        To:     Jared.Still_at_radisys.com, ORACLE-L_at_fatcity.com
        cc: 
        Subject:        RE: Checking the rebuildability of an index


I am no internals expert but even if the index has grown the access path should not be scanning the entire 68 meg or 30 meg for that matter. I guess
what I am getting at is maybe we need to see some real data here and see what we are getting for our money. Your points are well taken and I agree,
I have even probably been guilty of this myself at times :(

Ethan Post
perotdba (AIM), epost1 (Yahoo)


-----Original Message-----
Sent: Tuesday, August 06, 2002 3:47 PM
To: ORACLE-L_at_fatcity.com
Cc: Ethan.Post_at_ps.net

I don't do it often, but there are times that it's needed.

One I rebuilt recently went from 68 Meg to ~30 meg. This makes a significant reduction in time spent scanning that index, and reduces pressure on the cache buffer.

Most may not need rebuilt often, but you should be able to point at data telling you which ones should be rebuilt, which ones shouldn't be rebuilt, and why.

There's also the political CYA factor, such as the hot shot consultant that's checking out your systems and wants to know why your indexes haven't been rebuilt, or your buffer hit ratio is 65%, and then proceeds to report to management that you aren't doing your job.

You need to have convincing answers for these questions, backed up by data.

Jared

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Received on Tue Aug 06 2002 - 17:53:33 CDT

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