Re: UNNEST with multiple args, and TABLE with multiple funcs

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Andrew Gierth <andrew(at)tao11(dot)riddles(dot)org(dot)uk>
Cc: PG Hackers <pgsql-hackers(at)postgresql(dot)org>, Greg Stark <stark(at)mit(dot)edu>, David Fetter <david(at)fetter(dot)org>, Josh Berkus <josh(at)agliodbs(dot)com>
Subject: Re: UNNEST with multiple args, and TABLE with multiple funcs
Date: 2013-11-21 02:27:31
Message-ID: 28537.1385000851@sss.pgh.pa.us
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Andrew Gierth <andrew(at)tao11(dot)riddles(dot)org(dot)uk> writes:
> "Tom" == Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> writes:
> Tom> and this would result in producing the array elements as a table
> Tom> column. There is nothing in there about a function returning
> Tom> set.

> In the spec, there is no such thing as a function returning a set of
> rows in the sense that we use.

Right, but they do have a concept of arrays that's similar to ours,
and AFAICS the spec demands different behavior for an array-returning
function than what we've got here.

We could conceivably say that we'll implicitly UNNEST() if the function
returns array, and not otherwise --- but that seems pretty inconsistent
and surprise-making to me. I'm not too sure what to do if a function
returns setof array, either.

regards, tom lane

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