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From: Frédéric Yhuel <[email protected]>
To: David Mullineux <[email protected]>
To: Peter Eisentraut <[email protected]>
Cc: [email protected]
Subject: Re: Has gen_random_uuid() gotten much slower in v17?
Date: Wed, 20 Nov 2024 11:35:20 +0100
Message-ID: <[email protected]> (raw)
In-Reply-To: <CAGsyd8VBW+zwYuLEiJ3JC5NCFveumUiwhJQoS_-zvhnyfARcbQ@mail.gmail.com>
References: <CAGsyd8XBE7Ksq2Z75CTStrjSswOjVUE8S+i7qq1hGvYRj+_bcA@mail.gmail.com>
	<[email protected]>
	<CAGsyd8VBW+zwYuLEiJ3JC5NCFveumUiwhJQoS_-zvhnyfARcbQ@mail.gmail.com>



On 9/11/24 12:47, David Mullineux wrote:
> Good idea. Thanks.    I did check. It's not enabled by default but just 
> in case I did another build. This time explicitly defining --disable- 
> debug and --disable-cassert. And I tested. Still slower than old versions.
> 

4.5 seconds is very surprising.

on my machine:

postgres=# explain (analyze, costs off) select gen_random_uuid() from 
generate_series(1, 50000);
                                     QUERY PLAN 

----------------------------------------------------------------------------------
  Function Scan on generate_series (actual time=3.507..123.492 
rows=50000 loops=1)
  Planning Time: 0.031 ms
  Execution Time: 125.481 ms
(3 rows)

postgres=# select version();
                                            version 

----------------------------------------------------------------------------------------------
  PostgreSQL 18devel on x86_64-pc-linux-gnu, compiled by gcc (Debian 
12.2.0-14) 12.2.0, 64-bit

pg_config | grep CONFIGURE
CONFIGURE =  '--enable-cassert' '--enable-debug' '--with-python' 
'CFLAGS=-ggdb -Og -g3 -fno-omit-frame-pointer' '--prefix' 
'/postgres/pgenv/master'

> This feels like a build configuration problem. Just can't put my finger 
> on it yet.

Why not using a profiler to see what's going on?






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