Subject: Re: multivariate statistics v14
To: Robert Haas <robertmhaas@gmail.com>,
 Alvaro Herrera <alvherre@2ndquadrant.com>
References: <1bc2bd16-8e33-9e22-cdb1-9ddc38fedc4c@2ndquadrant.com>
 <20160321033440.GA350186@alvherre.pgsql>
 <CA+TgmoZw-Z+_mrT0KbYhq4KoEP_jgY_uosEd_LZDQg1-jzi5=w@mail.gmail.com>
Cc: Tatsuo Ishii <ishii@postgresql.org>,
 Kyotaro HORIGUCHI <horiguchi.kyotaro@lab.ntt.co.jp>,
 Jeff Janes <jeff.janes@gmail.com>,
 "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>
From: Tomas Vondra <tomas.vondra@2ndquadrant.com>
Message-ID: <c71b5b16-1fa8-2699-ae00-931cbb31098d@2ndquadrant.com>
Date: Mon, 21 Mar 2016 11:08:32 +0100
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Hi,

On 03/21/2016 10:34 AM, Robert Haas wrote:
> On Sun, Mar 20, 2016 at 11:34 PM, Alvaro Herrera
> <alvherre@2ndquadrant.com> wrote:
>> ObjectProperty[] contains a comment that the ACL is "same as relation",
>> but is that still correct, given that now stats may be related to more
>> than one relation?  Do we even know what the rules for ACLs on
>> cross-relation stats are?  One very simple way to get around this is to
>> dictate that all the rels must have the same owner.
>
> That's not really all that simple - you'd have to forbid changing
> the owner of a relation involved in multi-rel statistics, but that's
> horrible. Presumably at the very least you'd then have to find some
> way of allowing the owner of everything in the group to be changed
> at the same time, but that's a whole new innovation. I think this is
> a very messy line of attack.

I agree. I don't think we should / need to impose such additional 
restrictions (e.g. same owner for all tables).

I think for using the statistics (to compute estimates for a query), it 
should be enough that the user can access all the tables it's built on. 
Which happens somehow implicitly, and currently it's trivial as each 
statistics is built on a single table.

I don't have a clear idea what should we do in the future with multiple 
tables (e.g. when the statistics is built on 3 tables, the query is on 2 
of them and the user does not have access to the remaining one).

But maybe we need to support ACLs because of ALTER STATISTICS?

regards

-- 
Tomas Vondra                  http://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services


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