From: | Andrei Lepikhov <a(dot)lepikhov(at)postgrespro(dot)ru> |
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To: | Tomas Vondra <tomas(dot)vondra(at)enterprisedb(dot)com> |
Cc: | pgsql-hackers(at)postgresql(dot)org, Alexander Cheshev <alex(dot)cheshev(at)gmail(dot)com> |
Subject: | Re: Multidimensional Histograms |
Date: | 2024-01-07 10:22:59 |
Message-ID: | 62435ae5-15f3-4485-a8e5-4f50d3bc8c8b@postgrespro.ru |
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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
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