Re: Performance improvement for joins where outer side is unique

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: David Rowley <david(dot)rowley(at)2ndquadrant(dot)com>
Cc: PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Performance improvement for joins where outer side is unique
Date: 2017-01-26 19:34:17
Message-ID: 2414.1485459257@sss.pgh.pa.us
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David Rowley <david(dot)rowley(at)2ndquadrant(dot)com> writes:
> I've attached a version without outer unique.

I looked through this a bit, and the first thing I noticed was it doesn't
touch costsize.c at all. That seems pretty wrong; it's little help to
have a performance improvement if the planner won't pick the right plan
type. There were costsize.c changes in there back in April; what happened
to them?

regards, tom lane

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