public inbox for [email protected]  

help / color / mirror / Atom feed

From: wenhui qiu <[email protected]>
To: Shinya Kato <[email protected]>
Cc: Scott Ray <[email protected]>
Cc: Kyotaro Horiguchi <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Subject: Re: Report oldest xmin source when autovacuum cannot remove tuples
Date: Wed, 3 Jun 2026 10:32:07 +0800
Message-ID: <CAGjGUAKokqBPhw+56gU-3o3SOJe3d4TqPceCrS4K9gdYsw3ZsQ@mail.gmail.com> (raw)
In-Reply-To: <CAOzEurTohto7mfbmGu0GCHgAF+6roKxZgartyYydWsDkg3HzTg@mail.gmail.com>
References: <[email protected]>
	<3bnBUxwx2npXqvHL0trI11LOOvzQ7LI0GzWqbaj5SJnk7DTb1uzStGveKwj0JJmBW4ebzGIF3az7of4I4rQeaO_PRqDnnClCduPyjM6gPgM=@scottray.io>
	<CAOzEurTC+5xuH_X2EBWjW0Fs9iuTq3OMA=1FfT4xx1wYbCAR6g@mail.gmail.com>
	<[email protected]>
	<qOUvBIi7LC3GLKEjACMQAhPnYaE1m7Ta6XbMXN1gOVo3Mh6-Be6o_kQxQeCNXfo-Ywgc8k6myZrco4a41z-r7Dfqro4-nH73cB_tmSOczJk=@scottray.io>
	<CAOzEurTohto7mfbmGu0GCHgAF+6roKxZgartyYydWsDkg3HzTg@mail.gmail.com>

HI Shinya
> I agree that exposing xid horizon retention information via a
> SQL-visible interface is valuable. However, I believe reporting it
> in the VACUUM log is also important: a view only shows the current
> state, so once a blocker has gone away there is no way to determine,
> after the fact, what was holding the horizon back at the time a
> particular VACUUM ran. Logs are the only durable record we have for
> that kind of post-hoc analysis.
Agree +1,There's no denying that checking SQL is easier than checking logs.
Logs are also important though. In fact, I think we should apply this patch
first and implement the SQL later.

Thanks

On Wed, Jun 3, 2026 at 9:25 AM Shinya Kato <[email protected]> wrote:

> On Wed, Jun 3, 2026 at 10:05 AM Scott Ray <[email protected]> wrote:
> > I've been working on a view like this.  It shows the horizon
> > contribution for each backend, prepared xact, replication slot, and
> > HSF walsender, broken down by class.  It also shows - for each
> > contributor - how the horizon would shift if that holder were
> > removed.
> >
> > Shinya said [1] that we could have a view in the future.  We could
> > have both the logging and the view call a single function that reads
> > the procArray and other sources to gather the horizon information.  I
> > think the logging and the view would complement each other.
> >
> > Should I start another thread?
>
> My mild preference would be to keep the discussion on this thread,
> since the shared function design is central to both the log and the
> view and may be easier to keep aligned in one place. That said, I'm
> not strongly attached to that, so please pick whichever feels more
> convenient.
>
>
> --
> Best regards,
> Shinya Kato
> NTT OSS Center
>

view thread (34+ messages)  latest in thread

reply

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Reply to all the recipients using the --to and --cc options:
  reply via email

  To: [email protected]
  Cc: [email protected], [email protected], [email protected], [email protected], [email protected], [email protected], [email protected], [email protected]
  Subject: Re: Report oldest xmin source when autovacuum cannot remove tuples
  In-Reply-To: <CAGjGUAKokqBPhw+56gU-3o3SOJe3d4TqPceCrS4K9gdYsw3ZsQ@mail.gmail.com>

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

This inbox is served by agora; see mirroring instructions
for how to clone and mirror all data and code used for this inbox