Re: Oracle doesn't want to use bitmap index on partitioned table

You need to add some detail to this.
If you are partitioned by MONTH, is this by month number, with the month number as the partition key, or is the partition key the DATE with a month-based date range

When you 'pick a month', do you mean 'pick the whole month' or just 'pick a day in the month'.

Whatever the answer, the stats of your query are probably acting against you - if the partition is a date truncated to day, then picking one day from a month will mean ca. 3% of the partition, and there is a fairly low probability that Oracle will evaluate an index as being useful in this case.

Note: given the partition definition, Oracle does not need to examine the index to determine which partition to read.

Jonathan Lewis
Yet another Oracle-related web site: www.jlcomp.demon.co.uk

SV wrote in message <5H7w2.3833$fz.13505466_at_storm.twcol.com>...

>
>Here is the problem I ran into with 64-bit Oracle on HP-UX 11.0 640bit
>I have a partitioned table and I created a local bitmap index
>on that table. The table is partitioned by (month).
>The index works fine as long as I do not specify partition key (month)
>in the WHERE clause. But as soon as I pick particular
>month using WHERE clause, Oracle never uses bitmap
>index on that partition.
>Why is that?
>
>Thanks,
>Serge
>
>
Received on Wed Feb 10 1999 - 02:44:03 CST