| From: | "Scott Marlowe" <scott(dot)marlowe(at)gmail(dot)com> |
|---|---|
| To: | "Vladimir Sitnikov" <sitnikov(dot)vladimir(at)gmail(dot)com> |
| Cc: | "Tomas Vondra" <tv(at)fuzzy(dot)cz>, Andrus <kobruleht2(at)hot(dot)ee>, pgsql-performance(at)postgresql(dot)org |
| Subject: | Re: Using index for IS NULL query |
| Date: | 2008-11-11 23:34:42 |
| Message-ID: | dcc563d10811111534x3957273aw8365cb497cc0c91c@mail.gmail.com |
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| Lists: | pgsql-performance |
On Tue, Nov 11, 2008 at 4:00 PM, Vladimir Sitnikov
<sitnikov(dot)vladimir(at)gmail(dot)com> wrote:
>
>> Yes, NULL values are not stored in the index, but you may create
>> functional index on
>
> Are you sure NULL values are not stored? btree, gist and bitmap index and
> search for NULL values.
It's not that they're not stored, it's that before 8.3 pg didn't know
how to compare to them I believe. The standard trick was to create a
partial index with "where x is null" on the table / column. 8.3 knows
how to compare them and doesn't need the partial index.
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