Re: ANALYZE - Currupting Index

Hans Forbrich wrote:
>
> Are you sure that you are corrupting the index? Or is the
> system just running slower after analyze?
>
> Personally I've never run across Analyze corrupting an
> index (doesn't mean it can't hapopen - just never seen it).
>
> However, if your database allows 'COST' based optimization,
> I understand that running analyze provides the stats that
> are required for that kind of optimization. After analyze
> is run, the COST optimizer will kick in. In older versions
> (7.0, 7.1), the COST optimizer was not necessarily the best,
> and my experience was that it usually slowed down the runs.
> (With 7.2, COST seems to be OK).
>
> After analyzing, try dropping the stats to see if you
> get improvements.
>
> /hans

True!

The CBO will kick in if ANY table in the query has stats.

If you have a multi-table join and analyze only one index Oracle will have to estimate stats for everything else.

If you are going to use the CBO you should make sure ALL stats are up to date. Received on Mon Oct 07 1996 - 00:00:00 CEST