Subject: Re: In-placre persistance change of a relation

From: Heikki Linnakangas <[email-masked]>
Date: Fri, 3 Feb 2023 08:42:52 +0100

I want to call out this part of this patch:

> Also this allows for the cleanup of files left behind in the crash of
> the transaction that created it.

This is interesting to a lot wider audience than ALTER TABLE SET 
LOGGED/UNLOGGED. It also adds most of the complexity, with the new 
marker files. Can you please split the first patch into two:

1. Cleanup of newly created relations on crash

2. ALTER TABLE SET LOGGED/UNLOGGED changes

Then we can review the first part independently.

Regarding the first part, I'm not sure the marker files are the best 
approach to implement it. You need to create an extra file for every 
relation, just to delete it at commit. It feels a bit silly, but maybe 
it's OK in practice. The undo log patch set solved this problem with the 
undo log, but it looks like that patch set isn't going anywhere. Maybe 
invent a very lightweight version of the undo log for this?

- Heikki

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From: Kyotaro Horiguchi <[email-masked]>
Date: Tue, 07 Feb 2023 13:47:59 +0900 (JST)

Thank you for the comment!

At Fri, 3 Feb 2023 08:42:52 +0100, Heikki Linnakangas <[email-masked]> wrote in 
> Then we can review the first part independently.

Ah, indeed.  I'll do that.

> relation, just to delete it at commit. It feels a bit silly, but maybe

Agreed. (But I didn't come up with better idea..)

> it's OK in practice. The undo log patch set solved this problem with
> the undo log, but it looks like that patch set isn't going
> anywhere. Maybe invent a very lightweight version of the undo log for
> this?

I didn't thought on that line. Yes, indeed the marker files are a kind
of undo log.

Anyway, I'll split the current patch to two parts as suggested.

regards.

-- 
Kyotaro Horiguchi
NTT Open Source Software Center

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From: "Gregory Stark (as CFM)" <[email-masked]>
Date: Wed, 1 Mar 2023 14:56:25 -0500

> > I want to call out this part of this patch:

Looks like this patch has received some solid feedback from Heikki and
you have a path forward. It's not currently building in the build farm
either.

I'll set the patch to Waiting on Author for now.

-- 
Gregory Stark
As Commitfest Manager