Re: Statistics for CBO

Re: Statistics for CBO

 

  

Hi Deepesh,

ANALYZE actually put a shared lock on the object so that its structure can
not be alted during execution. Also it invalidates all the SQLs on that
object cached in the shared pool. But it does not prevent any DMLs.

ANALYZE with COMPUTE option will be a time consuming (depend on ur table
size). ESTIMATE will be fast and generate accurate statistics.

Rgds

Jomon


----- Original Message -----
From: "Deepesh Turkar" <Deepesh.[Email Address Removed] "LazyDBA.com Discussion" <[Email Address Removed] Friday, February 27, 2004 7:04 PM
Subject: RE: Statistics for CBO


> hi Deepak,
>
> To generate statistics for a table with analyze is used and analyze give
> the overhead. Analyzing a table is equivalent to building an index. An
> exclusive lock is taken on the table, preventing any DML updates until the
> ANALYZE has completed.More suprising is the amount of temporary disk space
> required.
>
> SO if frequently you generate the statistics it will effect the
performance
> of your database only becuase analyze commmand.
>
> it is depend you table size. If it is small then you can generate
> statistics.
>
> with regards
>
> Deepesh
>
> Agilisys
>
> -----Original Message-----
> From: Deepak Panda [mailto:[Email Address Removed] Sent: Friday, February 27, 2004 6:34 PM
> To: LazyDBA.com Discussion
> Subject: Statistics for CBO
>
>
> Hi Gurus,
>
> Will it be benificial if I collect statistics for a table which grows at
> a very faster rate?
>
> I am asking this because if i do this then i may need to collect the
> statistics quite frequently, so that the CBO can take the right
> decission while executing any query on the table.
>
> Can someone please throw some light on it?
>
> Thanks & Regards
>
> Deepak
>
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