Re: GATHER_STATS_JOB
- From: Adric Norris <spikey.mcmarbles@xxxxxxxxx>
- To: oracle-l <oracle-l@xxxxxxxxxxxxx>
- Date: Thu, 20 Aug 2009 08:42:16 -0500
On Thu, Aug 20, 2009 at 04:44, John Kanagaraj <john.kanagaraj@xxxxxxxxx>wrote:
> Gene,
>
> A larger problem with the default GATHER_STATS_JOB is that it creates
> Histograms by default on columns that it thinks are skewed. This can
> cause all sorts of issues. Further, the default for various options
> changed in 10g (including the out-of-box capability to collect stats).
> This causes enough headaches if you are not aware that it does this!
>
A standard part of my 10g database post-creation tasks is to change this
default using:
exec dbms_stats.set_param('METHOD_OPT','FOR ALL COLUMNS SIZE REPEAT')
This way, the GATHER_STATS_JOB will only generate histograms for columns
which already have them in place.
I'll probably revisit this strategy for our 11g databases, as I understand
that it handles histograms (and bind peeking) much better than previous
releases. Need to test it first, of course.
--
"I'm too sexy for my code." - Awk Sed Fred.
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