Re: Understanding how partial indexes work?

"Chris Velevitch" <chris(dot)velevitch(at)gmail(dot)com> writes:
> On Dec 7, 2007 2:39 AM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> Is it worth the trouble? You didn't mention the statistics involved,
>> but ordinarily I'd think a non-equal condition is too nonselective
>> to justify the cost of maintaining an extra index.

> Yes, I did neglect to mention the stats. Y is the status of the record
> which represents the life cycle of the record starting at zero and
> ending up at k3. So basically the query would retrieving and the
> partial index will indexing records which aren't at their end of life.
> So the number of records where Y <> k3 will be low and the number of
> records where Y = k3 will be growing over time.

OK, in that case the partial index might be worth trying.

regards, tom lane