Horton

Re: fix pg_mkdir_p to tolerate concurrent directory creation

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Álvaro Herrera <alvherre@kurilemu.de>
Cc: Andrew Dunstan <andrew@dunslane.net>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2026-06-19T14:51:02Z
Lists: pgsql-hackers 
=?utf-8?Q?=C3=81lvaro?= Herrera <alvherre@kurilemu.de> writes:
> Hmm, should the 'break's in the loop be 'continue's?  If you're creating
> path a/b/c, and a concurrent process beats you but is only attempting to
> do a/b, then with the break you'll fail to create the final c.

Maybe I'm confused, but I think it's right as-is.  The "break"s are
places where we're giving up and reporting a hard error.  If we want
to continue to the next directory level, we just fall through ---
and doing that with "continue" would be wrong because it'd miss the
step at the bottom of the loop:

		if (!last)
			*p = '/';


			regards, tom lane

Commits

  1. Make pg_mkdir_p() tolerant of a concurrent directory creation.