Re: Calculage avg. width when operator = is missing - Mailing list pgsql-hackers

From Shulgin, Oleksandr
Subject Re: Calculage avg. width when operator = is missing
Date
Msg-id CACACo5QrzDAuWyr2YW7_wRRu-8+Kr-Nb8aKw_zs8T0qLLiwGpw@mail.gmail.com
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In response to Re: Calculage avg. width when operator = is missing  (Alvaro Herrera <alvherre@2ndquadrant.com>)
Responses Re: Calculage avg. width when operator = is missing  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-hackers
On Tue, Sep 22, 2015 at 11:56 PM, Alvaro Herrera <alvherre@2ndquadrant.com> wrote:
Tom Lane wrote:

> Should we consider this HEAD-only, or a back-patchable bug fix?
> Or perhaps compromise on HEAD + 9.5?

It looks like a bug to me, but I think it might destabilize approved
execution plans(*), so it may not be such a great idea to back patch
branches that are already released.  I think HEAD + 9.5 is good.

(*) I hear there are even applications where queries and their approved
execution plans are kept in a manifest, and plans that deviate from that
raise all kinds of alarms.  I have never seen such a thing ...

Ugh.  Anyway, do you expect any plans to change only due to avg. width estimation being different?  Why would that be so?

--
Alex

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