Re: pgv18: simple table scan take more time than pgv14

From: Devrim Gündüz <devrim(at)gunduz(dot)org>
To: James Pang <jamespang886(at)gmail(dot)com>, pgsql-hackers(at)lists(dot)postgresql(dot)org
Subject: Re: pgv18: simple table scan take more time than pgv14
Date: 2025-06-21 11:13:54
Message-ID: 7c45639130261bbfdb20084e78380ed1f7283006.camel@gunduz.org
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Hi,

On Fri, 2025-06-20 at 09:46 +0800, James Pang wrote:
> same OS RHEL8, install pgv14.11 and pgv18.beta1_3, both installation
> by RPM from pgdg, and use similar postgresql.conf.

<snip>

> 18.beta1
> postgres=# \timing on
> Timing is on.
> postgres=# select * from tt where b ~~ 'a%';
>  a | b
> ---+---
> (0 rows)
>
> Time: 78.532 ms
> postgres=# select * from tt where b ~~ 'a%'
> postgres-# ;
>  a | b
> ---+---
> (0 rows)
>
> Time: 83.516 ms
> postgres=# select * from tt where b ~~ 'a%';
>  a | b
> ---+---
> (0 rows)

It's likely because v18 beta RPMs are built with --enable-debug and 
--enable-cassert . See the note on yum.postgresql.org:

https://yum.postgresql.org/rpmchart/#pg18

Regards,

--
Devrim Gündüz
Open Source Solution Architect, PostgreSQL Major Contributor
BlueSky: @devrim.gunduz.org , @gunduz.org

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