Re: Change in CTE treatment in query plans?

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: David Conlin <dc345(at)cantab(dot)net>
Cc: pgsql-performance(at)lists(dot)postgresql(dot)org
Subject: Re: Change in CTE treatment in query plans?
Date: 2019-10-17 09:04:32
Message-ID: 19441.1571303072@sss.pgh.pa.us
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David Conlin <dc345(at)cantab(dot)net> writes:
> Does anyone know if there's been a change in the way values for CTEs are
> displayed in query plans?

Offhand I don't recall any such changes, nor does a cursory look
through explain.c find anything promising.

If you're concerned with a multiply-referenced CTE, one possibility
for funny results is that the blame for its execution cost could be
spread across the multiple call sites. The same can happen with
initplans/subplans. But I'm just guessing; you didn't show any
concrete examples so it's hard to be definite.

regards, tom lane

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