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From: Joe Conway <mail@joeconway.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Christopher Kings-Lynne <chris.kings-lynne@calorieking.com>
Cc: Hackers (PostgreSQL) <pgsql-hackers@postgresql.org>
Cc: Andrew Dunstan <andrew@dunslane.net>
Cc: Bernd Helmle <mailings@oopsware.de>
Cc: Peter Eisentraut <peter_e@gmx.net>
Cc: Susanne Ebrecht <susanne.ebrecht@credativ.de>
Subject: Re: Values list-of-targetlists patch for comments (was Re: [PATCHES]
Date: Sat, 29 Jul 2006 18:24:54 -0700
Message-ID: <44CC0A66.6070903@joeconway.com> (raw)
In-Reply-To: <12029.1153760969@sss.pgh.pa.us>
References: <44B69778.5050104@dunslane.net>
	<50461.84.63.113.55.1152832991.squirrel@pezone.net>
	<ECCAAC0A3182895D3D12B0E8@[172.26.14.247]>
	<44B7ADFC.90205@dunslane.net>
	<44BC0432.3040509@joeconway.com>
	<44BC661F.80609@joeconway.com>
	<44BCD06C.3060409@calorieking.com>
	<44BCF1D4.3010807@dunslane.net>
	<5842.1153246741@sss.pgh.pa.us>
	<44BD8854.9060506@calorieking.com>
	<15212.1153279954@sss.pgh.pa.us>
	<44BDB2F5.7080003@joeconway.com>
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	<44C4F625.2050304@joeconway.com>
	<12029.1153760969@sss.pgh.pa.us>

Tom Lane wrote:
> If I'm reading the spec correctly, VALUES is exactly parallel to SELECT
> in the grammar, which means that to use it in FROM you would need
> parentheses and an alias:
> 
> 	SELECT ... FROM (SELECT ...) AS foo
> 
> 	SELECT ... FROM (VALUES ...) AS foo

One of the things I'm struggling with is lack of column aliases. Would 
it be reasonable to require something like this?

	SELECT ... FROM (VALUES ...) AS foo(col1, col2, ...)

The other issue is how to determine column type. Even better would be to 
require (similar to SRF returning record):

	SELECT ... FROM (VALUES ...) AS foo(col1 type1, col2 type2, ...)

This would unambiguously identify the column aliases and types. Assuming 
we stick with the spec:
	SELECT ... FROM (VALUES ...) AS foo

1. How should we assign column names?
      values1, values2, ...?
    or
      col1, col2, ...?
    or
      ???

2. How should we assign datatypes? Use the first "row" and try to coerce
    the rest to that type?

Joe



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