Re: long runtimes cured by cutting hash_area_size by 90% - ???

Yes - at least in some cases.

I don't think there is any way around problems of excessive disc activity, but v9 is much less profligate with memory.

In a 6 table hash, for example, one possible path is to hash 5 tables in memory at once, then run the 6th through them. In this case, Oracle 8 MAY allocated 5 x hash_area_size - even if the five tables are very small. Oracle 9 will use a more appropriate allocation of memory, whether or not you are using the pga_aggregate_target.

In a silly example, I saw Oracle 8 use something like 12MB of memory to hash a 4 row table - in circumstances where Oracle 9 used about 100K.

(I assume this is a bug)

Regards

Jonathan Lewis
http://www.jlcomp.demon.co.uk

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  who can answer the questions, but the
  person who can question the answers -- T. Schick Jr

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The Co-operative Oracle Users' FAQ
http://www.jlcomp.demon.co.uk/faq/ind_faq.html

• Original Message ----- To: "Multiple recipients of list ORACLE-L" <ORACLE-L_at_fatcity.com> Sent: 15 April 2003 04:08 ???

> You specifically mentioned Oracle 8 (inclusive of 8i I assume?).
Does your
> mention of 8 imply that 9i does a better job of exercising "damage
> limitation"?
>
> Regards,
>
> Larry G. Elkins
> elkinsl_at_flash.net
> 214.954.1781
>

-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.net
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Author: Jonathan Lewis
  INET: jonathan_at_jlcomp.demon.co.uk

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