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

Hi,

On 2025-06-20 09:46:06 +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.
> 

> 14.11

> Time: 55.082 ms
> postgres=# select * from tt where b ~~ 'a%';
>  a | b
> ---+---
> (0 rows)
> 
> Time: 54.716 ms

> 18.beta1
> postgres=# select * from tt where b ~~ 'a%';
>  a | b
> ---+---
> (0 rows)
> 
> Time: 77.117 ms

I tried but failed to reproduce this.  In fact, I see both 17 and 18 being
faster than 14.

Have you checked if 14 and 18 actually use the same collation?

Greetings,

Andres Freund