From: Mark D Powell <>
Date: Thu, 28 Feb 2008 07:31:47 -0800 (PST)
Message-ID: <>

On Feb 28, 9:14 am, "" <> wrote:
> To all,
> Have tar on this open, but support has been slow with updates.
> EE Sun 5.9 64 Bit.
> Anyway have this table, query is:
> SELECT record_key, t_id, '31-DEC-2099', 0
> FROM target_tab
> WHERE current_row = 'X'
> There is a bitmap index on current_row and it has two distinct values.
> For some reason (only in our prod) environment,
> DBMS_STATS.GATHER_SCHEMA_STATS (method_opt=> all indexed columns size
> 254) is generating the wrong data on that column. A quick check of
> dba_histograms shows an endpoint number of 0 and 1 after
> gather_Schema_stats. It does (properly according to 10053 trace and
> its stats) a full table scan.
> However, gather_table_Stats generates proper date (endpoints being
> 24035 and 5952162) and after it is run the query uses the index.
> I'm leaning towards this being a bug, but was wondering if anyone else
> had seen this behavior from DBMS_STATS before?
> Thanks

Have you compared the database parameters including underbar parameter settings to make sure there are no parameters set differently?

Are the patch levels 100% identical. Every dot patch potentially affects the CBO.

Lastly are you sure the sample size and sample method being used are the same?

If auto sample size is being used a difference in the data distribution could result in a different sample size which in turn could be resulting in significantly different statistics.

Also check if system statistics are in use as these will modify the cost calculations.

HTH -- Mark D Powell -- Received on Thu Feb 28 2008 - 09:31:47 CST

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