To: pgsql-sql@postgresql.org
From: =?UTF-8?B?SmFubiBSw7ZkZXI=?= <roederja@ethz.ch>
Subject: Table returning functions
Date: Wed, 08 Sep 2010 15:35:24 +0200
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Message-ID: <i683es$v8b$1@dough.gmane.org>
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Hi,
I have a question which does not seem to be covered in the
documentation: I have a function f(i) that returns a table with three
columns (a, b, c).

In the documentation
(http://www.postgresql.org/docs/8.4/interactive/xfunc-sql.html#XFUNC-SQL-FUNCTIONS-RETURNING-SET)
it says that (even though deprecated) you can call such functions in a
SELECT clause like so:

SELECT id, f(id) FROM some_table .

This will give me a two column table that looks like this:

id | (a, b, c)

However since I want a 4 column table like this
id | a | b | c

, I do this instead:

SELECT id, (f(id)).a, (f(id)).b, (f(id)).c FROM some_table.

However I'm not quite sure if this really gives me what I want (i.e. the
same as in the first query only with the tuple elements as separate
columns).

Of course I'm open to suggestions on how to do this more elegantly and
also how one can do something like this without using the deprecated
feature of calling a set returning function in SELECT.

Jann