Re: WIP: multivariate statistics / proof of concept
От | Tomas Vondra |
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Тема | Re: WIP: multivariate statistics / proof of concept |
Дата | |
Msg-id | 32d9bff1ca469f85d6fd3ad5db1237b2.squirrel@2.emaily.eu обсуждение исходный текст |
Ответ на | Re: WIP: multivariate statistics / proof of concept (David Rowley <dgrowleyml@gmail.com>) |
Ответы |
Re: WIP: multivariate statistics / proof of concept
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Список | pgsql-hackers |
Dne 29 Říjen 2014, 10:41, David Rowley napsal(a): > > I've not really gotten around to looking at the patch yet, but I'm also > wondering if it would be simple include allowing functional statistics > too. > The pg_mv_statistic name seems to indicate multi columns, but how about > stats on date(datetime_column), or perhaps any non-volatile function. This > would help to solve the problem highlighted here > http://www.postgresql.org/message-id/CAApHDvp2vH=7O-gp-zAf7aWy+A-WHWVg7h3Vc6=5pf9Uf34DhQ@mail.gmail.com > . Without giving it too much thought, perhaps any expression that can be > indexed should be allowed to have stats? Would that be really difficult to > implement in comparison to what you've already done with the patch so far? I don't know, but it seems mostly orthogonal to what the patch aims to do. If we add collecting statistics on expressions (on a single column), then I'd expect it to be reasonably simple to add this to the multi-column case. There are features like join stats or range type stats, that are probably more directly related to the patch (but out of scope for the initial version). > I'm quite interested in reviewing your work on this, but it appears that > some of your changes are not C89: > > src\backend\commands\analyze.c(3774): error C2057: expected constant > expression [D:\Postgres\a\postgres.vcxproj] > src\backend\commands\analyze.c(3774): error C2466: cannot allocate an > array of constant size 0 [D:\Postgres\a\postgres.vcxproj] > src\backend\commands\analyze.c(3774): error C2133: 'indexes' : unknown > size [D:\Postgres\a\postgres.vcxproj] > src\backend\commands\analyze.c(4302): error C2057: expected constant > expression [D:\Postgres\a\postgres.vcxproj] > src\backend\commands\analyze.c(4302): error C2466: cannot allocate an > array of constant size 0 [D:\Postgres\a\postgres.vcxproj] > src\backend\commands\analyze.c(4302): error C2133: 'ndistincts' : unknown > size [D:\Postgres\a\postgres.vcxproj] > src\backend\commands\analyze.c(4775): error C2057: expected constant > expression [D:\Postgres\a\postgres.vcxproj] > src\backend\commands\analyze.c(4775): error C2466: cannot allocate an > array of constant size 0 [D:\Postgres\a\postgres.vcxproj] > src\backend\commands\analyze.c(4775): error C2133: 'keys' : unknown size > [D:\Postgres\a\postgres.vcxproj] > > The compiler I'm using is a bit too stupid to understand the C99 syntax. > > I guess you'd need to palloc() these arrays instead in order to comply > with > the project standards. > > http://www.postgresql.org/docs/devel/static/install-requirements.html > > I'm going to sign myself up to review this, so probably my first feedback > would be the compiling problem. I'll look into that. The thing is I don't have access to MSVC, so it's a bit difficult to spot / fix those issues :-( regards Tomas
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