Re: Storing old stats
- From: breitliw@xxxxxxxxxxxxx
- To: "oracle-l@xxxxxxxxxxxxx" <oracle-l@xxxxxxxxxxxxx>, Orlando L <oralrnr@xxxxxxxxx>
- Date: Tue, 07 May 2013 13:00:57 -0600
If you use dbms_stats to gather statistics the prior statistics are
automatically save in statistics history tables and kept for n days (
31 by default, is configurable ). I am not a big fan of this - if
statistics for a table / index do not get gathered for more than 31
days ( e.g. because of too little activity ) the entire statistics
history is purged and if the next gather results in an undesirable plan
you can't revert back. I much prefer creating a stattab table and
exporting statistics "manually" either at regular intervals, i.e. prior
to a dbms_stats.gather, or prior to/after certain events.
On Tue, 7 May 2013 13:45:45 -0500, Orlando L <oralrnr@xxxxxxxxx> wrote:
List,
> One of our colleagues is suggesting that we create a backup table for
> exporting and storing statistics, in all databases, many of them 10g. The
> purpose of this backup table would be to store existing statistics when we
> have to tune queries; just save off the existing statistics of the tables
> involved in case if we have to revert back after new stats are collected.
> This sounds like a good idea to me, but I want to know how people here do
> it.
>
> I think in 11g there is a way to revert back the statistics within 24 hours.
>
> Orlando.
>
>
> --
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>
>
>
--
Wolfgang Breitling
Centrex Consulting Corporation
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