To: Michael Glaesmann <grzm@myrealbox.com>
Cc: pgsql-novice@postgresql.org
Subject: Re: Functional index problems. (Was: Many joins: monthly summaries
	S-L--O--W)
In-reply-to: <7141E2A2-04BE-11D8-81AE-0005029FC1A7@myrealbox.com> 
References: <7141E2A2-04BE-11D8-81AE-0005029FC1A7@myrealbox.com>
Comments: In-reply-to Michael Glaesmann <grzm@myrealbox.com>
	message dated "Thu, 23 Oct 2003 03:34:59 +0900"
Date: Wed, 22 Oct 2003 15:17:58 -0400
Message-ID: <18109.1066850278@sss.pgh.pa.us>
From: Tom Lane <tgl@sss.pgh.pa.us>

Michael Glaesmann <grzm@myrealbox.com> writes:
> On Thursday, Oct 23, 2003, at 02:44 Asia/Tokyo, Tom Lane wrote:
>> 7.4 is more flexible though --- it will take the above as long as you
>> put an extra set of parentheses in there...

> I took a gander at the documentation for 7.4beta. I can tell it's been 
> reorganized. There's no longer a specific section on functional indexes 
> that I can see, though there is mention of it in the SQL CREATE INDEX 
> entry 
> <http://developer.postgresql.org/docs/postgres/sql-createindex.html> 
> The 7.3.2 documents I have say that there cannot be multicolumn 
> functional indexes, though there's no mention of this in the new 
> documentation. Does this mean this proscription has been lifted?

Yes.  Any column of an index can now be an expression; the former
functional-index capability is now just a special case of "expressional
indexes".  For syntactic reasons we had to require an extra pair of
parens around expressions in the CREATE INDEX statement --- although
it proved possible to not require these when the expression looks like
a standard-syntax function call, thus providing backwards compatibility
with the old functional-index syntax.  See
http://developer.postgresql.org/docs/postgres/indexes-expressional.html
as well as the CREATE INDEX reference page.

I'm not particularly happy with the phrase "expressional index", and
would like to think of something else to use before the 7.4 docs go
final.  Any ideas?

			regards, tom lane