Re: performance profit after reorganisation

"Joachim Misselbeck" <joachim.misselbeck_at_gmx.net> wrote in message news:<9sgad3$rpc$01$1_at_news.t-online.com>...
> Hi to all,
>
> have any body experince about table/tablespace reorg and the profit ( I/O,
> CPU Util., etc. ) ? Or a link to more information about this ?
>
>
> Thanks for all answers
>
> Joe
>
> p.s.
> I know the orginal Statment of Oracle ( You don't need this at any time ,
> but it's not really true )

The performance benefit from performing table and index reorganizations is totally dependent on the environment in question and the changes applied to the environment by the reorgaization.

Example - There is generally no benefit from unloading and reloading a table that has had no deletes executed against it unless it is relocated to a different less busy disk or if it had been built with an excessive and unneeded pctfree, say 50%, and the blocks are half empty and it is rebuild with say a pctfree of 5% so that the rebuilt table is now 45% smaller than it was and full table scans are ran against the table. If all the access is single row retrieval by PK then the rebuild would not help performance-wise except to make space available for other objects, which is a valid reasone to re-org.

• Mark D Powell --