Re: Database creation performance drop going from pg 14 to pg 15+

[Mahdi Bahrami]

Thanks for the hint, that was exactly it! I also asked the original author of 
the issue and he has confirmed the performance of pg 15+ now matches those of 
pg 13/14.

As mentioned "This issue is not necessarily a big deal to us, but can anyone 
please explain the why?" so it was partially out of curiosity, and partially 
because of the way the author of the issue is using Postgres which apparently 
is sensitive to these milliseconds.

Not exactly sure what's their set up, but they did mention with the PostgresNIO 
SASL improvements which saves only some 10-20-30-40 milliseconds or so, their 
tests now run in 15s instead of 1m30s, which then it means they can now use pg 
versions higher than pg 13 and still have around the same performance.
I think they run tests in parallel, and they possibly recreate the whole DB 
once for each test.

Re: Database creation performance drop going from pg 14 to pg 15+

[Thomas Munro]

On Wed, May 28, 2025 at 11:09 PM Mahdi Bahrami  wrote:
> their tests now run in 15s instead of 1m30s

Wow.  If/when they get to v18, they might also try setting
file_copy_method=clone when using strategy=file_copy.

Re: Database creation performance drop going from pg 14 to pg 15+

[Mahdi Bahrami]

To be clear the "15s instead of 1m30s" was related to another issue about SASL 
implementation of PostgresNIO being slow, not this CREATE DATABASE strategy 
change. I was just trying to explain that in their set up, these saved 
milliseconds do matter for whatever reason.