Re: Out parameters handling

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Gregory Stark <stark(at)enterprisedb(dot)com>
Cc: Robert Haas <robertmhaas(at)gmail(dot)com>, Rod Taylor <rod(dot)taylor(at)gmail(dot)com>, Josh Berkus <josh(at)agliodbs(dot)com>, Asko Oja <ascoja(at)gmail(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Out parameters handling
Date: 2009-03-07 17:25:38
Message-ID: 14761.1236446738@sss.pgh.pa.us
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Gregory Stark <stark(at)enterprisedb(dot)com> writes:
> I'm not sure that's any better. The case where I've run into this is when I
> have something like:
> balance := new value
> UPDATE tab SET balance = balance
> In that case the only way we could get it right is if we default to the local
> variable but only in contexts where an expression is valid.

AFAICS getting that "right" would require the parser to develop advanced
mind reading capabilities. We could probably fix it to know that the
first "balance" must be a table column name, but there is no principled
way to make a choice about the second one; and you could easily invent
slightly different scenarios where resolving it as the column name is
the right thing.

Anyway, I'm unsure whether this is related to the complaints upthread,
which is why I was asking.

regards, tom lane

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