| From: | Nathan Bossart <nathandbossart(at)gmail(dot)com> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | pgsql-hackers(at)lists(dot)postgresql(dot)org, alex work <alexwork033(at)gmail(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com> |
| Subject: | Re: Slow GRANT ROLE on PostgreSQL 16 with thousands of ROLEs |
| Date: | 2024-03-22 00:51:39 |
| Message-ID: | 20240322005139.GA2060816@nathanxps13 |
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| Lists: | pgsql-general pgsql-hackers |
On Thu, Mar 21, 2024 at 03:40:12PM -0500, Nathan Bossart wrote:
> On Thu, Mar 21, 2024 at 04:31:45PM -0400, Tom Lane wrote:
>> I don't think we have any really cheap way to de-duplicate the role
>> OIDs, especially seeing that it has to be done on-the-fly within the
>> collection loop, and the order of roles_list is at least potentially
>> interesting. Not sure how to make further progress without a lot of
>> work.
>
> Assuming these are larger lists, this might benefit from optimizations
> involving SIMD intrinsics. I looked into that a while ago [0], but the
> effort was abandoned because we didn't have any concrete use-cases at the
> time. (I'm looking into some additional optimizations in a separate thread
> [1] that would likely apply here, too.)
Never mind. With the reproduction script, I'm only seeing a ~2%
improvement with my patches.
--
Nathan Bossart
Amazon Web Services: https://aws.amazon.com
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