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Re: pgv18: simple table scan take more time than pgv14 - Mailing list pgsql-hackers

From James Pang
Subject Re: pgv18: simple table scan take more time than pgv14
Date
Msg-id CAHgTRfeb12cq1QivgKD1qMee3dipg27rp8Sxt-LoyKLn=gSp2g@mail.gmail.com
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In response to Re: pgv18: simple table scan take more time than pgv14  (Devrim Gündüz <devrim@gunduz.org>)
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install 18.beta1 from source ,remove enable_debug, much better now. it's better than pgv14.11. 

postgres=# select * from tt where b ~~ 'a%';
 a | b
---+---
(0 rows)

Time: 67.545 ms
postgres=# select * from tt where b ~~ 'a%';
 a | b
---+---
(0 rows)

Time: 50.945 ms
postgres=# select * from tt where b ~~ 'a%';
 a | b
---+---
(0 rows)

Time: 48.176 ms
postgres=# select * from tt where b ~~ 'a%';
 a | b
---+---
(0 rows)

Time: 49.919 ms

Thanks,

James

Devrim Gündüz <devrim@gunduz.org> 於 2025年6月21日週六 下午7:13寫道：
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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