I believe an import will populate the number of rows column in DBA_TABLES by
default, so unless you want histograms, I believe it's already analyzed
after an import.
michael_bialik_at_my-deja.com wrote in message <7q9aqq$ko8$1_at_nnrp1.deja.com>...
>In article <37C7854E.BCD1E518_at_synergy-infotech.com>,
> Anurag Minocha <anurag_at_synergy-infotech.com> wrote:
>> Hi,
>> I am a little confused about Cost Based Optimization.Please help me
>out.
>>
>> 1.Does the cost based optimization work on those sql queries which
>dont
>> have hints specified in them.?
>>
>> 2. How frequently should the tables be analysed.
>>
>> Any help will be greatly appreciated.
>>
>> Thanks
>> anurag
>>
>> also reply to
>> anurag_at_synergy-infotech.com
>>
>>
> Hi.
>
> 1. Yes. CBO works for queries accessing any of the
> analyzed tables.
> If you are making a join of n tables and only one of them
> is analyzed - CBO assumes that all other tables have 0 rows
> and usually uses FULL access for them.
> 2. Analyze your table after EXP/IMP, initial load and any data load
> that may affect data distribution.
> Consider using "ESTIMATE STATISTICS" instead of "COMPUTE"
> for large tables.
>
> Good luck. Michael.
>
>
>Sent via Deja.com http://www.deja.com/
>Share what you know. Learn what you don't.
Received on Sun Aug 29 1999 - 00:25:27 CDT
