Re: PATCH: add support for IN and @> in functional-dependency statistics use

From: Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com>
To: Dean Rasheed <dean(dot)a(dot)rasheed(at)gmail(dot)com>
Cc: Pierre Ducroquet <p(dot)psql(at)pinaraf(dot)info>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>
Subject: Re: PATCH: add support for IN and @> in functional-dependency statistics use
Date: 2020-03-17 17:05:17
Message-ID: 20200317170517.hutarq3sioyny3wa@development
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On Tue, Mar 17, 2020 at 04:14:26PM +0000, Dean Rasheed wrote:
>On Tue, 17 Mar 2020 at 15:37, Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com> wrote:
>> On Tue, Mar 17, 2020 at 12:42:52PM +0000, Dean Rasheed wrote:
>> >The other thing that I'm still concerned about is the possibility of
>> >returning estimates with P(a,b) > P(a) or P(b). I think that such a
>> >thing becomes much more likely with the new types of clause supported
>> >here, because they now allow multiple values from each column, where
>> >before we only allowed one. I took another look at the patch I posted
>> >on the other thread, and I've convinced myself that it's correct.
>> >Attached is an updated version, with some cosmetic tidying up and now
>> >with some additional regression tests.
>> Yeah, I agree that's something we need to fix. Do you plan to push the
>> fix, or do you want me to do it?
>I can push it. Have you had a chance to review it?

Not yet, I'll take a look today.


Tomas Vondra
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

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