Horton

Re: Weird failure with latches in curculio on v15

Nathan Bossart <nathandbossart@gmail.com>

View thread View on postgr.es
From: Nathan Bossart <nathandbossart@gmail.com>
To: Andres Freund <andres@anarazel.de>
Cc: Michael Paquier <michael@paquier.xyz>, Tom Lane <tgl@sss.pgh.pa.us>, Thomas Munro <thomas.munro@gmail.com>, Fujii Masao <fujii@postgresql.org>, Postgres hackers <pgsql-hackers@lists.postgresql.org>
Date: 2023-02-05T23:57:47Z
Lists: pgsql-hackers 
On Sun, Feb 05, 2023 at 03:01:57PM -0800, Andres Freund wrote:
> I think at the very least you'd want to have a separate callback for
> restoring segments than for restoring other files. But more likely a
> separate callback for each type of file to be restored.
> 
> For the timeline history case an parameter indicating that we don't want
> to restore the file, just to see if there's a conflict, would make
> sense.

That seems reasonable.

> For the segment files, we'd likely need a parameter to indicate whether
> the restore is random or not.

Wouldn't this approach still require each module to handle restoring ahead
of time?  I agree that the shell overhead isn't the main performance issue,
but it's unclear to me how much of this should be baked into PostgreSQL.  I
mean, we could introduce a GUC that tells us how far ahead to restore and
have a background worker (or multiple background workers) asynchronously
pull files into a staging directory via the callbacks.  Is that the sort of
scope you are envisioning?

-- 
Nathan Bossart
Amazon Web Services: https://aws.amazon.com

Commits

  1. Avoid calling proc_exit() in processes forked by system().

  2. Move extra code out of the Pre/PostRestoreCommand() section.

  3. Revert refactoring of restore command code to shell_restore.c

  4. Refactor code in charge of running shell-based recovery commands

  5. Clean up inconsistent use of fflush().

  6. Report wait events for local shell commands like archive_command.