Re: [PATCH] Hooks at XactCommand level

From: Gilles Darold <gilles(at)darold(dot)net>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Nicolas CHAHWEKILIAN <leptitstagiaire(at)gmail(dot)com>
Cc: pgsql-hackers(at)lists(dot)postgresql(dot)org
Subject: Re: [PATCH] Hooks at XactCommand level
Date: 2021-07-05 10:48:01
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Le 01/07/2021 à 18:47, Tom Lane a écrit :
> Nicolas CHAHWEKILIAN <leptitstagiaire(at)gmail(dot)com> writes:
>> As far as I am concerned, I am totally awaiting for this kind of feature
>> exposed here, for one single reason at this time : the extension
>> pg_statement_rollback will be much more valuable with the ability of
>> processing "rollback to savepoint" without the need for explicit
>> instruction from client side (and this patch is giving this option).
> What exactly do these hooks do that isn't done as well or better
> by the RegisterXactCallback and RegisterSubXactCallback mechanisms?
> Perhaps we need to define some additional event types for those?
> Or pass more data to the callback functions?
> I quite dislike inventing a hook that's defined as "run during
> start_xact_command", because there is basically nothing that's
> not ad-hoc about that function: it's internal to postgres.c
> and both its responsibilities and its call sites have changed
> over time. I think anyone hooking into that will be displeased
> by the stability of their results.

Sorry Tom, it seems that I have totally misinterpreted your comments,
google translate was not a great help for my understanding but Julien
was. Thanks Julien.

I'm joining a new patch v4 that removes the need of any hook and adds a
can be cautch in the xact callbacks when a new command is to be executed.

Gilles Darold

Attachment Content-Type Size
command-start-finish-hook-v4.patch text/x-patch 2.9 KB

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