Re: temporary tablespace estimation.

Hatzistavrou Giannis wrote:
>
> Dear All,
>
> I have the following questions to make:
>
> a) In a select statement where there is no order by or group by clause but
> parallel query servers are used, do these servers use temporary tablespace
> segments?

  Quite likely, if the volume requires it. 'Temporary space', as the name indicates, holds data in the course of processing, before Oracle is able to reach the final result. With parallel query servers, each one fetches a partial result set, which has to be stored somewhere before everything is merged. Even if you have no 'sort', you have a 'merge' phase. If that's you were thinking of, I do not believe that you get results on the fly from each of the parallel query servers, it would make communications much too complicated between the client and the server side. When you issue a 'fetch' call, you expect it from a single source and everything needs to be streamlined somewhere.

> b) how can someone estimate the temporary space used having only the select
> statement?

 I wonder!

-- 
Regards,

Stephane Faroult
Oriole Ltd
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Author: Stephane Faroult
  INET: sfaroult_at_oriole.com

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