Re: does anybody recomends using dbms_stats.gather_schema_stats with for columnns size skewonly
- From: Mladen Gogala <gogala@xxxxxxxxxxxxx>
- To: aleon68@xxxxxxxxx
- Date: Mon, 17 Jan 2005 00:39:33 +0000
On 01/16/2005 05:15:54 PM, Alfonso Le?n wrote:
> Hello:
>=20
> What is the recomended aproach to collect the statistics?
>=20
> Thanks in advance for your suggestions
My advice is to collect statistics in two passes:
1) Estimate (compute) statistics for tables and indexes.
2) Collect column histograms
Two passes are necessary, because collecting column histograms misses =20
row statistics for the table. Here is how a typical "COMPUTE" script =20
would look like, in my world:
DBMS_STATS.GATHER_DATABASE_STATS (
estimate_percent =3D> NULL,
block_sample =3D> FALSE,
method_opt =3D> 'FOR TABLE',
granularity =3D> 'DEFAULT',
cascade =3D> TRUE,
options =3D> 'GATHER');
DBMS_STATS.GATHER_DATABASE_STATS (
estimate_percent =3D> NULL,
block_sample =3D> FALSE,
method_opt =3D> 'FOR COLUMNS SIZE SKEWONLY',
degree =3D> NULL,
granularity =3D> 'DEFAULT',
cascade =3D> FALSE,
options =3D> 'GATHER');
--=20
Mladen Gogala
Oracle DBA
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