Re: multivariate statistics v14

Hi,

On 03/21/2016 10:34 AM, Robert Haas wrote:
> On Sun, Mar 20, 2016 at 11:34 PM, Alvaro Herrera
> <alvherre(at)2ndquadrant(dot)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
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