Re: multivariate statistics v14

>> Do you have any other missing parts in this work? I am asking
>> because I wonder if you want to push this into 9.6 or rather 9.7.
>
> I think the first few parts of the patch series, namely:
>
> * shared infrastructure (0002)
> * functional dependencies (0003)
> * MCV lists (0004)
> * histograms (0005)
>
> might make it into 9.6. I believe the code for building and storing
> the different kinds of stats is reasonably solid. What probably needs
> more thorough review are the changes in clauselist_selectivity(), but
> the code in these parts is reasonably simple as it only supports using
> a single multi-variate statistics per relation.
>
> The part (0006) that allows using multiple statistics (i.e. selects
> which of the available stats to use and in what order) is probably the
> most complex part of the whole patch, and I myself do have some
> questions about some aspects of it. I don't think this part might get
> into 9.6 at this point (although it'd be nice if we managed to do
> that).

Hum. So without 0006 or beyond, there's not much benefit for the
PostgreSQL users, and you are not too confident about 0006 or
beyond. Then I would think it is a little bit hard to justify in
putting 000[2-5] into 9.6. I really like this feature and would like
to see in PostgreSQL someday, but I'm not sure if we should put the
patches (0002-0005) into PostgreSQL now. Please let me know if there's
some reaons we should put the patches into PostgreSQL now.

Best regards,
--
Tatsuo Ishii
SRA OSS, Inc. Japan
English: http://www.sraoss.co.jp/index_en.php
Japanese:http://www.sraoss.co.jp