Horton

Re: logical decoding and replication of sequences, take 2

Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>

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From: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>
To: Tomas Vondra <tomas.vondra@enterprisedb.com>
Cc: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, Masahiko Sawada <sawada.mshk@gmail.com>, Amit Kapila <amit.kapila16@gmail.com>, Peter Eisentraut <peter.eisentraut@enterprisedb.com>
Date: 2023-07-14T14:02:27Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Migrate logical slots to the new node during an upgrade.

  2. Make test_decoding ddl.out shorter

  3. Fix snapshot handling in logicalmsg_decode

  4. doc: Adjust a few more references to "postmaster"

  5. Revert "Logical decoding of sequences"

On Fri, Jul 14, 2023 at 4:10 PM Tomas Vondra
<tomas.vondra@enterprisedb.com> wrote:
>
> I don't think that's true - this will create 1 record with
> "created=true" (the one right after the CREATE SEQUENCE) and the rest
> will have "created=false".

I may have misread the code.

>
> I realized I haven't modified seq_desc to show this flag, so I did that
> in the updated patch version, which makes this easy to see.

Now I see it. Thanks for the clarification.

> >
> > Am I missing something here?
> >
>
> You're missing the fact that pg_upgrade does not copy replication slots,
> so the restart_lsn does not matter.
>
> (Yes, this is pretty annoying consequence of using pg_upgrade. And maybe
> we'll improve that in the future - but I'm pretty sure we won't allow
> decoding old WAL.)

Ah, I see. Thanks for correcting me.

> >>>
> >>
> >> Hmmmm, that might work. I feel a bit uneasy about having to keep all
> >> relfilenodes, not just sequences ...
> >
> > From relfilenode it should be easy to get to rel and then see if it's
> > a sequence. Only add relfilenodes for the sequence.
> >
>
> Will try.
>

Actually, adding all relfilenodes to hash may not be that bad. There
shouldn't be many of those. So the extra step to lookup reltype may
not be necessary. What's your reason for uneasiness? But yeah, there's
a way to avoid that as well.

Should I wait for this before the second round of review?

-- 
Best Wishes,
Ashutosh Bapat