Date: Mon, 25 Mar 2024 10:16:47 -0500
From: Nathan Bossart <nathandbossart@gmail.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: pgsql-hackers@lists.postgresql.org, alex work <alexwork033@gmail.com>,
	Robert Haas <robertmhaas@gmail.com>
Subject: Re: Slow GRANT ROLE on PostgreSQL 16 with thousands of ROLEs
Message-ID: <20240325151647.GA2662364@nathanxps13>
References: <20240322144739.GA2321246@nathanxps13>
 <20240322145532.GA2346110@nathanxps13>
 <907785.1711121266@sss.pgh.pa.us>
 <20240322163952.GA2347986@nathanxps13>
 <939945.1711126395@sss.pgh.pa.us>
 <20240322165448.GA2350322@nathanxps13>
 <20240322193506.GA2352051@nathanxps13>
 <1084642.1711140109@sss.pgh.pa.us>
 <20240325144743.GA2618709@nathanxps13>
 <2490242.1711379319@sss.pgh.pa.us>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <2490242.1711379319@sss.pgh.pa.us>
Archived-At: <https://www.postgresql.org/message-id/20240325151647.GA2662364%40nathanxps13>
Precedence: bulk

On Mon, Mar 25, 2024 at 11:08:39AM -0400, Tom Lane wrote:
> * The magic constants (crossover list length and bloom filter size)
> need some testing to see if there are better values.  They should
> probably be made into named #defines, too.  I suspect, with little
> proof, that the bloom filter size isn't particularly critical --- but
> I know we pulled the crossover of 1000 out of thin air, and I have
> no certainty that it's even within an order of magnitude of being a
> good choice.

I'll try to construct a couple of tests to see if we can determine a proper
order of magnitude.

> * Code needs more than zero comments.

Yup.

> * Is it worth trying to make a subroutine, or at least a macro,
> so as not to have 2 copies of the code?

I think so.  I'll try that in the next version.

-- 
Nathan Bossart
Amazon Web Services: https://aws.amazon.com