Re: plans for bitmap indexes?

Josh Berkus wrote:
> Chris,
> 
> 
>>The most nearly comparable thing is be the notion of "partial
>>indexes," where, supposing you had 60 region codes (e.g. - 50 US
>>states, 10 Canadian provinces), you might set up indices thus:
> 
> 
> I'm afraid that you're mistaken about the functionality of bitmap indexes.   
> The purpose of a bitmap index is not to partition an index, but to allow 
> multiple indexes to be used in the same operation.
> 
> For example, imagine you have a table on a dating website with 18 columns 
> representing 18 different characteristics for matching.  Imagine that you 
> index each of those columns seperately. If you do:
> 
> SELECT * FROM people WHERE orientation = 'gay' AND gender = 'male' AND city = 
> 'San Francisco';

> ... then the planner can use an index on orientation OR on gender OR on city, 
> but not all three.   Multicolumn indexes are no solution for this use case 
> because you'd have to create a multicolumn index for each possible combo of 
> two or three columns ( 18! ).    

I'm wondering if in some cases the following query could be more efficient

select * from people where orientation = 'gay'
intersect
select * from people where gender = 'male'
intersect
select * from people where city =





Regards
Gaetano Mendola