Message-ID: <62435ae5-15f3-4485-a8e5-4f50d3bc8c8b@postgrespro.ru>
Date: Sun, 7 Jan 2024 17:22:59 +0700
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Subject: Re: Multidimensional Histograms
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To: Tomas Vondra <tomas.vondra@enterprisedb.com>
Cc: pgsql-hackers@postgresql.org, Alexander Cheshev <alex.cheshev@gmail.com>
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From: Andrei Lepikhov <a.lepikhov@postgrespro.ru>
Organization: Postgres Professional
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On 7/1/2024 06:54, Tomas Vondra wrote:
> It's an interesting are for experiments, no doubt about it. And if you
> choose to explore it, that's fine. But it's better to be aware it may
> not end with a commit.
> For the multi-dimensional case, I propose we first try to experiment
> with the various algorithms, and figure out what works etc. Maybe
> implementing them in python or something would be easier than C.

Curiously, trying to utilize extended statistics for some problematic 
cases, I am experimenting with auto-generating such statistics by 
definition of indexes [1]. Doing that, I wanted to add some hand-made 
statistics like a multidimensional histogram or just a histogram which 
could help to perform estimation over a set of columns/expressions.
I realized that current hooks get_relation_stats_hook and 
get_index_stats_hook are insufficient if I want to perform an estimation 
over a set of ANDed quals on different columns.
In your opinion, is it possible to add a hook into the extended 
statistics to allow for an extension to propose alternative estimation?

[1] https://github.com/danolivo/pg_index_stats

-- 
regards,
Andrei Lepikhov
Postgres Professional