From: Tom Lane <tgl@sss.pgh.pa.us>
To: David Rowley <dgrowleyml@gmail.com>
cc: Richard Guo <guofenglinux@gmail.com>,
        PostgreSQL-development <pgsql-hackers@postgresql.org>
Subject: Re: A performance issue with Memoize
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Comments: In-reply-to David Rowley <dgrowleyml@gmail.com>
	message dated "Fri, 26 Jan 2024 16:23:46 +1300"
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Date: Thu, 25 Jan 2024 22:51:49 -0500
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David Rowley <dgrowleyml@gmail.com> writes:
> I've adjusted the comments to what you mentioned and also leaned out
> the pretty expensive test case to something that'll run much faster
> and pushed the result.

+1, I was wondering if the test could be cheaper.  It wasn't horrid
as Richard had it, but core regression tests add up over time.

>> However ... it seems like we're not out of the woods yet.  Why
>> is Richard's proposed test case still showing
>> +         ->  Memoize (actual rows=5000 loops=N)
>> +               Cache Key: t1.two, t1.two
>> Seems like there is missing de-duplication logic, or something.

> This seems separate and isn't quite causing the same problems as what
> Richard wants to fix so I didn't touch this for now.

Fair enough, but I think it might be worth pursuing later.

			regards, tom lane