From: | Dima Tkach <dmitry(at)openratings(dot)com> |
---|---|
To: | Stephan Szabo <sszabo(at)megazone23(dot)bigpanda(dot)com> |
Cc: | pgsql-general(at)postgresql(dot)org |
Subject: | Re: Index not used with IS NULL |
Date: | 2003-02-17 14:43:02 |
Message-ID: | 3E50F4F6.5000704@openratings.com |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-general |
>
>
>Yes, this solution does double index the NULLs, but if you have alot of
>NULLs you probably should be doing a seqscan to find them anyway and don't
>need the index. High update frequency costs you the NULL check, which is
>a little annoying, and if you've got a small number of NULL rows or the
>data is clustered in some fashion (so that the index is a win) that have
>lots of updates this may become significant.
>
>
Yeah... But imagine the real-life condition, when I have a *moderate*
number of nulls (not enough to justify a seq.scan, but still a lot) in
*several* different columns - so that, instead of creating a single
multi-column index, I would have to create a whole bunch of them with
different predcates - where this is null and that is not null, where
this is null and tha is null etc, etc...
That's what annoys me a lot here :-(
From | Date | Subject | |
---|---|---|---|
Next Message | Tom Lane | 2003-02-17 15:10:28 | Re: Index not used with IS NULL |
Previous Message | Dima Tkach | 2003-02-17 14:39:55 | Re: Index not used with IS NULL |