Re: functions returning records

From: Karel Zak <zakkr(at)zf(dot)jcu(dot)cz>
To: Alex Pilosov <alex(at)pilosoft(dot)com>
Cc: pgsql-hackers(at)postgresql(dot)org
Subject: Re: functions returning records
Date: 2001-06-27 07:10:52
Message-ID: 20010627091051.H10253@ara.zf.jcu.cz
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On Tue, Jun 26, 2001 at 05:11:47PM -0400, Alex Pilosov wrote:
> I started thinking about Tom's idea to implement functions as table
> source.
>
> To me, it seems that a very few changes are necessary:
> a) parser must be changed to allow functioncall to be a table_ref
> (easy)
>
> b) when a Query node is generated out of such a call "select * from foo()"
> it should be almost identical to one generated out of "select * from
> (select * from foo)" with one distinction: list of query attributes should
> be completed based on return type of foo().

For the result from foo() you must somewhere define attributes (names).
Where? In CREATE FUNCTION statement? Possible must be:

select name1, name2 from foo() where name1 > 10;

What returns foo()? ...the pointer to HeapTuple or something like this or
pointer to some temp table?

> c) executor should support execution of such Query node, properly
> extracting things out of function's return value and placing them into
> result attributes.

d) changes in fmgr

e) SPI support for table building/filling inside foo()

IMHO very cool and nice feature, but not easy for imlementation.

Karel

--
Karel Zak <zakkr(at)zf(dot)jcu(dot)cz>
http://home.zf.jcu.cz/~zakkr/

C, PostgreSQL, PHP, WWW, http://docs.linux.cz, http://mape.jcu.cz

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