What is the impact if Stats Gather runs in business hours.

Question

Hi
I have a Production Database in which Stats gather is running every alternative day as per the business requirement.
This Stats gather job starts at 7 PM. As data growing in this Database Time taken for this Job also increasing.
Now a days, This job is taking more than 14 hours to Analyze the Production Schema! It is completing at
9 AM in next day by the time business time starts.
Below is the script which we are using.
EXEC DBMS_STATS.GATHER_SCHEMA_STATS(ownname=>'${schema_name}',estimate_percent=>'',method_opt => 'FOR ALL COLUMNS SIZE
AUTO',cascade => TRUE,options=>'GATHER');
1. Is it recommended to run the stats gather in business hours?
2. How can We tune this Schema gather, so that this will take less time.
Appreciate the help.
Thanks in Advance.

Answer 1

Hello,
Gathering statistics is an heavy operation which should be done out from the Business hours.
If you are in *10g* or *11g*, normally every night (after 10 PM) the statistics are gathered.
Else, you can also use the following option:
options            => 'GATHER STALE' By that way, You would speed up analyze by analyzing only tables with more than 10% data change. But the MONITORING option must be enabled first on each Table.
You may find here some tracks about GATHER_STALE option:
http://asktom.oracle.com/pls/asktom/f?p=100:11:0::::P11_QUESTION_ID:2453570168793
Hope this help.
Best regards,
Jean-Valentin