Re: Extended statistics is not working on Vars hidden under a RelabelType

From: Robert Haas <robertmhaas(at)gmail(dot)com>
To: David Rowley <david(dot)rowley(at)2ndquadrant(dot)com>
Cc: PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>, Álvaro Herrera <alvaro(dot)herrera(at)2ndquadrant(dot)com>, Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com>
Subject: Re: Extended statistics is not working on Vars hidden under a RelabelType
Date: 2017-10-14 17:49:54
Message-ID: CA+TgmoZAhopLYsAqhmYZUuM16ZLG4Fsu9fp50F3uv=za4QYWvg@mail.gmail.com
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On Fri, Oct 13, 2017 at 4:49 PM, David Rowley
<david(dot)rowley(at)2ndquadrant(dot)com> wrote:
> tps = 8282.481310 (including connections establishing)
> tps = 8282.750821 (excluding connections establishing)

vs.

> tps = 8520.822410 (including connections establishing)
> tps = 8521.132784 (excluding connections establishing)
>
> With the patch we are making use of the extended statistics, which we
> do expect to be more work for the planner. Although, we didn't add
> extended statistics to speed up the planner.

Sure, I understand. That's actually a pretty substantial regression -
I guess that means that it's pretty important to avoid creating
extended statistics that are not needed, at least for short-running
queries.

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

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