On R, 2004-10-08 at 12:45, Yann Michel wrote:
> Hi,
>
> On Fri, Oct 08, 2004 at 10:09:18AM +0100, Dave Page wrote:
> > I think what Reini was asking was why do you think you need bitmap
> > indexes as opposed to any existing type?
>
> due to I'm developing a datawarehousing application we have lots of
> fact-data in our central fact-table. As I know how to improve
> performance on Oracle based datawarehouses, I'm used to add bitmap
> indexes for atributes having only a few distinct values.
> So I was looking for any comparable indexing technology but didn't find
> any so far.
There is currently no suitable index type for this type of queries (huge
tables with a few distinct values).
You may try to optimise performance by partitioning your fact tables on
these few dimension values by using table inheritance or union all
views.
There was a discussion on partitioning postgres tables on
pgsql-performance list a few days ago.
-------------
Hannu
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TIP 9: the planner will ignore your desire to choose an index scan if your
joining column's datatypes do not match
