Re: Multidimensional Histograms

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