Re: immutable functions vs. join for lookups ?

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Greg Stark <gsstark(at)mit(dot)edu>
Cc: "Merlin Moncure" <merlin(dot)moncure(at)rcsonline(dot)com>, "Dawid Kuroczko" <qnex42(at)gmail(dot)com>, pgsql-performance(at)postgresql(dot)org
Subject: Re: immutable functions vs. join for lookups ?
Date: 2005-04-18 19:50:26
Message-ID: 25151.1113853826@sss.pgh.pa.us
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Greg Stark <gsstark(at)mit(dot)edu> writes:
> Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> writes:
>> It would be interesting sometime to try to teach the planner about
>> inlining SQL-language functions to become joins. That is, given

> The Inlining of the function is presumably a side-issue. I have tons of
> queries that use subqueries in the select list for which the same behaviour
> would be appropriate.

Yeah, I was actually thinking about a two-step process: inline the
function to produce somethig equivalent to a handwritten scalar
sub-SELECT, and then try to convert sub-SELECTs into joins.

regards, tom lane

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