Daniel Castro wrote:
> Hi,
>
> I want to know the % of rows to be used as sample_rows for a
> table, because
> I get the following message:
>
> I 1 tables contain > 1.000.000 records but only 20.000 rows
> will be sampled
> for statistics
> CON: NUM_TABS_FEW_SAMPLE_ROWS > 0
> VAL: 1
>
> Is there any pattern?
> How I change this value?
>
> Best Regards,
Hi Daniel,
our recommendation is to use a sample rate of 5% for at least all tables with more than
1000000 rows.
But from my point of view you could also use it for smaller tables as long as the runtime
of the
update statistic command doesn't influence your system to much.
You could change the sample rate with "alter table <table name> sample <unsigned
int> percent | rows".
To check the actual sample rate use "select schemaname, tablename , sample_percent,
sample_rows from tables".
Kind regards
Holger
Holger Becker
MaxDB&liveCache
SAP AG
www.sap.com
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