Re: DWH : Index on Partition Key s

Stephane,

Thanks for your response.
Apparently in a partition for a month (uh oh !! : PARTITION_KEY='200910310000') , *all* the rows have the same PARTITION_KEY value.
Thus, a Month Partition has the same pseudo-date value stored in all the rows. So, the index is utterly useless.

As for multi-column indexes, so far (in this design) I've seen them only for the Primary Key.
Other indexes are single-column indexes. Not even BitMap indexes on the FACT table --- had they been BitMaps, Oracle could have been doing an AND on the BitMaps.

This is an absolutely non-Oracle design on an Oracle database. The database is just a "data store".
Ugh !

Hemant
Hemant K Chitale

http://hemantoracledba.blogspot.com

At 11:48 PM Friday, Stephane Faroult wrote:
>Hemant,
>
>I don't see the point if you have any prefixed local index, but if you
>have none, if you have one partition by month and most queries hit a
>single day or less, then this index *might*, depending on volume, etc,
>etc. benefit those queries.
>But then perhaps you could begin to question the partition grain ...
>
>By the way a lot of developers seem never to have been told that you
>could index several columns at once. Or it's just the developers that
>work on the applications I have to audit.
>
>S Faroult

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