Re: Logical replication timeout problem

From: Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>
To: Ashutosh Bapat <ashutosh(dot)bapat(dot)oss(at)gmail(dot)com>
Cc: "wangw(dot)fnst(at)fujitsu(dot)com" <wangw(dot)fnst(at)fujitsu(dot)com>, Fabrice Chapuis <fabrice636861(at)gmail(dot)com>, Euler Taveira <euler(at)eulerto(dot)com>, Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com>, "Hayato Kuroda (Fujitsu)" <kuroda(dot)hayato(at)fujitsu(dot)com>, Peter Smith <smithpb2250(at)gmail(dot)com>, Simon Riggs <simon(dot)riggs(at)enterprisedb(dot)com>, Petr Jelinek <petr(dot)jelinek(at)enterprisedb(dot)com>, "tanghy(dot)fnst(at)fujitsu(dot)com" <tanghy(dot)fnst(at)fujitsu(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>, Ajin Cherian <itsajin(at)gmail(dot)com>
Subject: Re: Logical replication timeout problem
Date: 2023-01-18 12:30:12
Message-ID: CAA4eK1+AdHBca2p4aspe90Zbqu+=pDoWUs33nY1qrKfdKRMuyw@mail.gmail.com
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On Wed, Jan 18, 2023 at 5:37 PM Ashutosh Bapat
<ashutosh(dot)bapat(dot)oss(at)gmail(dot)com> wrote:
>
> On Wed, Jan 18, 2023 at 1:49 PM wangw(dot)fnst(at)fujitsu(dot)com
> <wangw(dot)fnst(at)fujitsu(dot)com> wrote:
> >
> > On Wed, Jan 18, 2023 at 13:29 PM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
> > > On Tue, Jan 17, 2023 at 6:41 PM Ashutosh Bapat
> > > <ashutosh(dot)bapat(dot)oss(at)gmail(dot)com> wrote:
> > > >
> > > > On Tue, Jan 17, 2023 at 3:34 PM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
> > > >
> > > > > >
> > > > > > I am a bit worried about the indirections that the wrappers and hooks
> > > > > > create. Output plugins call OutputPluginUpdateProgress() in callbacks
> > > > > > but I don't see why ReorderBufferProcessTXN() needs a callback to
> > > > > > call OutputPluginUpdateProgress.
> > > > > >
> > > > >
> > > > > Yeah, I think we can do it as we are doing the previous approach but
> > > > > we need an additional wrapper (update_progress_cb_wrapper()) as the
> > > > > current patch has so that we can add error context information. This
> > > > > is similar to why we have a wrapper for all other callbacks like
> > > > > change_cb_wrapper.
> > > > >
> > > >
> > > > Ultimately OutputPluginUpdateProgress() will be called - which in turn
> > > > will call ctx->update_progress.
> > > >
> > >
> > > No, update_progress_cb_wrapper() should directly call
> > > ctx->update_progress(). The key reason to have a
> > > update_progress_cb_wrapper() is that it allows us to add error context
> > > information (see the usage of output_plugin_error_callback).
> >
> > I think it makes sense. This also avoids the need for every output plugin to
> > implement the callback. So I tried to improve the patch based on this approach.
> >
> > And I tried to add some comments for this new callback to distinguish it from
> > ctx->update_progress.
>
> Comments don't help when using cscope or some such code browsing tool.
> Better to use a different variable name.
>

+ /*
+ * Callback to be called when updating progress during sending data of a
+ * transaction (and its subtransactions) to the output plugin.
+ */
+ ReorderBufferUpdateProgressCB update_progress;

Are you suggesting changing the name of the above variable? If so, how
about apply_progress, progress, or updateprogress? If you don't like
any of these then feel free to suggest something else. If we change
the variable name then accordingly, we need to update
ReorderBufferUpdateProgressCB as well.

--
With Regards,
Amit Kapila.

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