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Re: Do I need to rebuild my indexes?

From: Eric Lansu <eric.lansu_at_quicknet.nl>
Date: Wed, 27 Sep 2000 15:47:17 +0200
Message-Id: <10632.117982@fatcity.com>


A truncated tables has empty indexes. When filling the table up again, the indexes are filled too. No worries there. Of what I haven't got any evidence yet is the following;

Is the index faster when rebuild AFTER the table fill, or is the internal structure exactly the same as when filled WHILE filling the table. Someone told me there's no difference, even when creating the index AFTER the table is filled, the records are inserted one by one in the index, someone else told me Oracle can make a better index from a filled table.

Is this what you mean by your question?

Eric Lansu

> One of our databases has a table with 22 million rows
> in it that got corrupted data in it. In order to fix the corrupted
> data, a temporary table was created, the data was written
> to the temp table, cleansed, the original table was truncated,
> and the clean data was written back to the original table
> pretty much in primary key order.
>
> I think we need to drop and recreate or at least rebuild
> the indexes now that the table has been truncated
> and the data rewritten. A fellow DBA maintains that there
> is no value in doing so. Surely performance will suffer
> if we don't rebuild the indexes. Is this not true? How
> much benefit will be get in dropping and recreating
> the indexes as opposed to rebuilding them as opposed
> to leaving them as is?
>
> Thanks,
Received on Wed Sep 27 2000 - 08:47:17 CDT

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