UPDATE - bitmap conversion on a index that is not bitmapped ???

 OK. How about this .... I checked the script for the index rebuilds. It did an 'alter index rebuild .... parallel 10 ...' After the rebuilds, we thought parallel 10 was not good, since Oracle cannot use PQO for a index read. We set the degree back to 1. Once a analyze was done, performance dropped.

So as a test, I just set the degree 10 on the index, did an estimate statistics. Ran a plan, and it is now using the BITMAP conversion - which is great for performance. 2 questions remain:

1. This is not a bitmapped index! So how does this work?
2. How does the degree affect all of this? Obviously it does.

Sorry for the rants, but this is very crazy in my opinion.

TIA. John  

-----Original Message-----
Sent: Wednesday, October 15, 2003 3:39 PM To: Multiple recipients of list ORACLE-L

Missed one important point. You can disable that by setting _b_tree_bitmap_plans to FALSE. Deleting the stats may not be a right apporach as that may screwup some other plans.

Sorry for missing the important one..

KG

• Original Message ----- To: "Multiple recipients of list ORACLE-L" <ORACLE-L_at_fatcity.com> Sent: Wednesday, October 15, 2003 10:39 PM

> John:
>
> Optimizer is a smart boy!!! He knows the column has few distinct values
> and decides the BITMAP access would be appropriate and making BITMAP
> plans from the BTree indexes. If you delete the stats for that index,
> you will get the old behavior.
>
> KG
>
>
>
> =====
> Have a nice day !!
> ------------------------------------------------------------
> Best Regards,
> K Gopalakrishnan,
> Bangalore, INDIA.
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> Please see the official ORACLE-L FAQ: http://www.orafaq.net
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