| From: | Heikki Linnakangas <heikki(at)enterprisedb(dot)com> |
|---|---|
| To: | Ron Mayer <rm_pg(at)cheapcomplexdevices(dot)com> |
| Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, pgsql-hackers(at)postgreSQL(dot)org |
| Subject: | Re: Index AM change proposals, redux |
| Date: | 2008-04-14 14:08:31 |
| Message-ID: | 4803655F.90005@enterprisedb.com |
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| Lists: | pgsql-hackers |
Ron Mayer wrote:
> Then I wonder if I can conceive of yet another related
> index type that'd be useful for such clustered tables. If
> I had something like GIT that stored something like
> "values State='CA' can be found on pages 1000 through 10000
> and 20000 through 21000" would it be even more effective on
> such a table than GIT?
Yep, a bitmap index.
Bitmap indexes don't actually work quite like that, but the point is
that it is very efficient on a column with few distinct values, and even
more so if the table is clustered on that column.
--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com
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