Horton

RE: logical decoding and replication of sequences, take 2

Hayato Kuroda (Fujitsu) <kuroda.hayato@fujitsu.com>

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From: "Hayato Kuroda (Fujitsu)" <kuroda.hayato@fujitsu.com>
To: 'Tomas Vondra' <tomas.vondra@enterprisedb.com>, Amit Kapila <amit.kapila16@gmail.com>
Cc: "Zhijie Hou (Fujitsu)" <houzj.fnst@fujitsu.com>, Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, Masahiko Sawada <sawada.mshk@gmail.com>, Peter Eisentraut <peter.eisentraut@enterprisedb.com>, Dilip Kumar <dilipbalaut@gmail.com>
Date: 2023-12-03T12:55:56Z
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"

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Dear Tomas,

> > I did also performance tests (especially case 3). First of all, there are some
> > variants from yours.
> >
> > 1. patch 0002 was reverted because it has an issue. So this test checks whether
> >    refactoring around ReorderBufferSequenceIsTransactional seems really
> needed.
> 
> FWIW I also did the benchmarks without the 0002 patch, for the same
> reason. I forgot to mention that.

Oh, good news. So your bench markings are quite meaningful.

> 
> Interesting, so what exactly does the transaction do?

It is quite simple - PSA the script file. It was executed with 64 multiplicity.
The definition of alter_sequence() is same as you said.
(I did use normal bash script for running them, but your approach may be smarter)

> Anyway, I don't
> think this is very surprising - I believe it behaves like this because
> of having to search in many hash tables (one in each toplevel xact). And
> I think the solution I explained before (maintaining a single toplevel
> hash, instead of many per-top-level hashes).

Agreed. And I can benchmark again for new ones, maybe when we decide new
approach.

Best Regards,
Hayato Kuroda
FUJITSU LIMITED