Re: Improve planner cost estimations for alternative subplans

From: Alexey Bashtanov <bashtanov(at)imap(dot)cc>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com>
Cc: Melanie Plageman <melanieplageman(at)gmail(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Improve planner cost estimations for alternative subplans
Date: 2020-07-24 14:57:39
Message-ID: 64896725-33ed-4084-1e7c-402f22bc3525@imap.cc
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Hi Tom,

sorry for the delay,
> I experimented with adding a number-of-evaluations parameter to
> cost_qual_eval, and found that the majority of call sites do have
> something realistic they can pass. The attached very-much-WIP
> patch shows my results so far. There's a lot of loose ends:
I like the idea, so if we alternative subplans remain there
I think we should implement it.

Best, Alex

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