Horton

Re: global / super barriers (for checksums)

Andres Freund <andres@anarazel.de>

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From: Andres Freund <andres@anarazel.de>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Daniel Gustafsson <daniel@yesql.se>, Magnus Hagander <magnus@hagander.net>, "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>
Date: 2019-12-12T19:54:20Z
Lists: pgsql-hackers 
Hi,

On 2019-12-11 13:35:26 -0500, Robert Haas wrote:
> While I have passionate philosophical feelings about this topic, for
> purposes of the present thread the really important question (IMV,
> anyway) is whether there's any way of getting a patch for global
> barriers committed in advance of the first user of such barriers.

Right. I think there is.


> If not, then I guess we'll need to decide which of checksum
> enable/disable and ALTER SYSTEM READ ONLY is going to go first and
> commit this only when that patch is ready to go as well. Or, I
> suppose, commit it with a dummy placeholder that then gets replaced by
> whichever patch goes first, but I'm not sure whether people would be
> OK with that.

I'd either add a test (if we have some) or placeholder kind
initially. But I'd also be ok with going for either of the other
versions directly - but it seems harder to tackle the patches together.

Greetings,

Andres Freund

Commits

  1. Online enabling and disabling of data checksums

  2. Extend the ProcSignal mechanism to support barriers.

  3. Partially deduplicate interrupt handling for background processes.

  4. Use PostgresSigHupHandler in more places.

  5. Move interrupt-handling code into subroutines.

  6. Use procsignal_sigusr1_handler for auxiliary processes.