Re: Inherited indexes.

Well, I never said unique, but you're correct, it's pretty undesirable
to put a global index on your partitioning key.

On Tue, Oct 04, 2005 at 06:16:21PM +0200, Zeugswetter Andreas DAZ SD wrote:
>
> > Another possibility is optimizing for the special case of
> > indexing on a partitioning key. In this case, index values
> > would be very localized to one table, so just storing the
> > table info on each index page (or something similar) would work well.
>
> If you have the partitioning key in the index and the partitions don't
> overlap, it is better to create separate [unique] indexes on the
> subtables.
> Building separate indexes per partition is usually preferred because of:
> 1. performance of dropping a partition
> 2. smaller index for CE
>
> Only if you need an "order by" without a sort step, that spawns more
> than one partition
> things usually get ugly. Imho the best solution would be a merge node,
> that merges results of
> several index accesses to avoid a sort and still use separate indexes.
> Such
> a merge node could probably also detect the case where accessing
> partitions in a certain
> order still produces ordered results.
>
> Usually you will only want the "one big unique index" when the
> partitioning is not
> reflectable in the index keys, and then (also in other db's) such an
> index is usually a pain ...
>
> Andreas
>
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