RE: optimize hash join between 2 large tables

  • From: <Paula_Stankus@xxxxxxxxxxxxxxx>
  • To: <mgogala@xxxxxxxxxxxxxxxxxxxx>
  • Date: Fri, 21 Jan 2005 10:03:55 -0500

Don't think I would do this for a batch process that runs in 2 hours
when the OLTP system is working smoothly.  Sounds like a lot of
complexity and not worth the issues it might bring up.  However, an
interesting exercise to do in a test environment.

Thanks Mladen.

-----Original Message-----
From: Mladen Gogala [mailto:mgogala@xxxxxxxxxxxxxxxxxxxx]=20
Sent: Friday, January 21, 2005 9:58 AM
To: Stankus, Paula G
Cc: oracle-l@xxxxxxxxxxxxx
Subject: Re: optimize hash join between 2 large tables

Paula_Stankus@xxxxxxxxxxxxxxx wrote:

>Other then use sort_area_size to sort in memory and parallel query what

>can be done to optimize a pull of 2 large tables joined together where=20
>most of the rows from both tables are selected???
> =20
You can put them in a 16K blocksize tablespace. That will speed up the
full table scan, but may also have some undesired consequences as Oracle
will need to maintain another buffer pool, another set of LRU latches,
probably another DBWR and it can be quite an interesting thing in
conjunction with workarea_size_policy set to auto.

Mladen Gogala
Oracle DBA
Ext. 121

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