From: | Ben <midfield(at)gmail(dot)com> |
---|---|
To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
Cc: | pgsql-performance(at)postgresql(dot)org |
Subject: | Re: encourging bitmap AND |
Date: | 2010-12-23 21:01:48 |
Message-ID: | 2879498D-E897-4FD0-8A73-52BF85B65D1C@gmail.com |
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Lists: | pgsql-performance |
On Dec 23, 2010, at 12:52 PM, Tom Lane wrote:
> Ben <midfield(at)gmail(dot)com> writes:
>> i have a schema similar to the following
>
>> create index foo_s_idx on foo using btree (s);
>> create index foo_e_idx on foo using btree (e);
>
>> i want to do queries like
>
>> select * from foo where 150 between s and e;
>
> That index structure is really entirely unsuited to what you want to do,
> so it's not surprising that the planner isn't impressed with the idea of
> a bitmap AND.
>
> I'd suggest setting up something involving a gist index over an
> interval-ish datatype. The PERIOD datatype that Jeff Davis is fooling
> with would do what you want --- see
> http://pgfoundry.org/projects/temporal
> http://thoughts.j-davis.com/2009/11/08/temporal-keys-part-2/
> If you don't want any add-on parts involved, you could fake it by using
> a box or possibly lseg.
Thanks for the quick response. I've already played a lot with the PERIOD datatype and GIST, it works pretty good, but I found that the lack of statistics and real selectivity functions hurt me. I was experimenting with the two column setup as an alternative, but if you think this is a dead end I'll look elsewhere.
Best regards, Ben
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