Reducing CPU Impact of DML's on LOB Segments.

From: Fmhabash <>
Date: Thu, 21 May 2009 22:51:07 -0400
Message-ID: <>

We have a case where an application using a JMS (Java messeging) involving a high frequent DML operational set of LOB insert, update, and delete statements. When this set runs against the db, we see an increase in system CPU which, in the past, had some undesirable effects on overall application performance.

We are looking into ways we can optimize the DML work run agaist the db and specifically on these LOB segments. I have done some research today using ML, developer guides and db admin guide and came up with some potential ideas.

  1. Enable caching for these lob segments and to avoid buffer interferance with application data, we can dedicate a separate block size for this data in the sga.
  2. disable 'logging' on the lob segments, but this will affect our standby configuration.
  3. Not sure if changing the chuncksize (is 8k now) will have any effect on performance and reducing IO load.

If you have experienced a lob related performance issues, please comment on the above and share.

Thank You.
-- Received on Thu May 21 2009 - 21:51:07 CDT

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