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Re: Bundle of patches

From: Teodor Sigaev <teodor(at)sigaev(dot)ru>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: pgsql-hackers(at)postgresql(dot)org, Patches <pgsql-patches(at)postgresql(dot)org>
Subject: Re: Bundle of patches
Date: 2006-12-04 20:03:37
Message-ID: 45747F19.3080506@sigaev.ru (view raw or flat)
Thread:
Lists: pgsql-hackerspgsql-patches
> And what happens when we implement NULLS FIRST/LAST correctly?  This is
> really a poor choice of representation.

If it's just appending of indexscan's it's not a problem...

> 
> One thing I find questionable about this is the assumption that indexes
> can support "foo IS NULL" and "foo IS NOT NULL" searches equally
> conveniently.  This is demonstrably false for, say, hash.  (Hash could
> store null keys by assigning them a fixed hashcode, say 0.  Then it
> would be able to handle IS NULL searches, but not IS NOT NULL, because
> it can't do full-index scans.)

Is there a guarantee that hash value of some not-null keys doesn't equal to 
special hash code?

> 
> the patch to do IS NULL only.  But if we are going areto support both,
> we probably have to have two pg_am flags not one.

GiST isn't effective with single NOT NULL condition ... So, using two flags may 
be useful.

-- 
Teodor Sigaev                                   E-mail: teodor(at)sigaev(dot)ru
                                                    WWW: http://www.sigaev.ru/

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