Horton

Re: Slow catchup of 2PC (twophase) transactions on replica in LR

Peter Smith <smithpb2250@gmail.com>

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From: Peter Smith <smithpb2250@gmail.com>
To: "Hayato Kuroda (Fujitsu)" <kuroda.hayato@fujitsu.com>
Cc: Amit Kapila <amit.kapila16@gmail.com>, "Zhijie Hou (Fujitsu)" <houzj.fnst@fujitsu.com>, "pgsql-hackers@lists.postgresql.org" <pgsql-hackers@lists.postgresql.org>, Vitaly Davydov <v.davydov@postgrespro.ru>, Ajin Cherian <itsajin@gmail.com>
Date: 2024-07-17T03:31:14Z
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. Fix random failure in 021_twophase.

  2. Allow altering of two_phase option of a SUBSCRIPTION.

  3. Doc: use true|false rather than on|off for "failover" option

  4. Support an optional asynchronous commit mode, in which we don't flush WAL

Attachments

Here are some review comments for patch v18-0002.

======
src/backend/commands/subscriptioncmds.c

1. CheckAlterSubOption

1a.
It's not obvious why we are only checking the 'slot name' when
needs_update==true, but OTOH is always checking the  'enabled' state.

~

1b.
Param 'needs_update' is a vague name. It needs more explanatory comments or
a better name. e.g. First impression was "Why are we calling 'Alter'
function if needs_update is false?". I know it encapsulates some common
code, but if special cases cause the logic to be more confusing then that
cost may outweigh the benefit of this function.

~

1c.
If the error checks can be moved to be done up-front, then all the
'needs_update' can be combined. Avoiding multiple checks to 'needs_update'
will make this function simpler.

~~~

AlterSubscription:
nitpick - typo /needs/need/
nitpick - typo /wo_phase/two_phase/
nitpick - The comment wording "the later part...", was confusing. I've
reworded the whole comment. But this belongs in patch 0001.

======
src/test/subscription/t/021_twophase.pl

nitpick - Use the same "###############################" comment style as
in patch 0001 to indicate each main TEST scenario.

======
99.
Please refer to the diffs attachment patch, which implements any nitpicks
mentioned above.

======
Kind Regards,
Peter Smith.
Fujitsu Australia