Re: slowest tap tests - split or accelerate?

Hi,

On 2022-01-19 09:42:31 -0800, Andres Freund wrote:
> Both ours have this. Unfortunately on windows cp doesn't natively
> exist. Although git does provide it. I tried a few things that appear to be
> natively available (time is best of three executions):
>
> gnu cp from git, cp -a tmp_install\initdb_template t\
> 670ms
>
> xcopy.exe /E /Q tmp_install\initdb_template t\
> 638ms

This errors out if there's any forward slashes in paths, thinking it's a
flag. Seems out.

> robocopy /e /NFL /NDL tmp_install\initdb_template t\
> 575ms
>
> So I guess we could use robocopy? That's shipped as part of windows starting in
> windows 10... xcopy has been there for longer, so I might just default to that.

It's part of of the OS back to at least windows 2016. I've found some random
links on the webs saying that it's included "This command is available in
Vista and Windows 7 by default. For Windows XP and Server 2003 this tool can
be downloaded as part of Server 2003 Windows Resource Kit tools. ".

Given that our oldest supported msvc version only runs on Windows 7 upwards
[2], I think we should be good?

Alternatively we could lift copydir() to src/common? But that seems like a bit
more work than I want to put in.

For a second I was thinking that using something like copy --reflink=auto
could make a lot of sense for machines like florican, removing most of the IO
from a "templated initdb". But it looks like freebsd doesn't have that, and
it'd be a pain to figure out whether cp has --reflink.

Greetings,

Andres Freund

[1] https://www.windows-commandline.com/download-robocopy/
[2] https://docs.microsoft.com/en-us/visualstudio/releases/2013/vs2013-sysrequirements-vs