Re: Using multiple extended statistics for estimates

From: Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com>
To: Mark Dilger <hornschnorter(at)gmail(dot)com>
Cc: PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Using multiple extended statistics for estimates
Date: 2019-12-05 17:15:54
Message-ID: 20191205171554.leclyueirbwun7dp@development
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On Sun, Dec 01, 2019 at 08:08:58PM +0100, Tomas Vondra wrote:
>On Sat, Nov 30, 2019 at 03:01:31PM -0800, Mark Dilger wrote:
>>Are you planning to submit a revised patch for this?
>Yes, I'll submit a rebased version of this patch shortly. I got broken
>because of the recent fix in choose_best_statistics, shouldn't take long
>to update the patch. I do have a couple more related patches in the
>queue, so I want to submit them all at once.

OK, here we go - these two patched allow applying multiple extended
statistics, both for MCV and functional dependencies. Functional
dependencies are simply merged and then applied at once (so withouth
choose_best_statistics), statistics are considered in greedy manner by
calling choose_best_statistics in a loop.

I do have some additional enhancements in the queue, but those are not
fully baked yet, so I'll post them later in separate patches.


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

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