| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org> |
| Cc: | Joel Jacobson <joel(at)compiler(dot)org>, Joe Conway <mail(at)joeconway(dot)com>, pgsql-hackers(at)lists(dot)postgresql(dot)org |
| Subject: | Re: [PATCH] pg_permissions |
| Date: | 2021-03-26 13:16:07 |
| Message-ID: | 1577736.1616764567@sss.pgh.pa.us |
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| Lists: | pgsql-hackers |
Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org> writes:
> On 2021-Mar-26, Joel Jacobson wrote:
>> On Thu, Mar 25, 2021, at 17:51, Tom Lane wrote:
>> I wonder what performance will be like with lots o' objects.
> I guess he is concerned about the number of catalog accesses.
My concern is basically that you're forcing the join between
pg_shdepend and $everything_else to be done as a nested loop.
It will work well, up to where you have so many objects that
it doesn't ... but the planner will have no way to improve it.
Having said that, I don't really see a better way either.
Materializing $everything_else via a UNION ALL seems like
no fun from a maintenance perspective, plus we're not that
great on optimizing such constructs either.
regards, tom lane
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