Horton

Re: [HACKERS] logical decoding of two-phase transactions

vignesh C <vignesh21@gmail.com>

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From: vignesh C <vignesh21@gmail.com>
To: Peter Smith <smithpb2250@gmail.com>
Cc: PostgreSQL Hackers <pgsql-hackers@postgresql.org>
Date: 2021-03-12T05:07:47Z
Lists: pgsql-hackers 
On Thu, Mar 11, 2021 at 7:20 AM Peter Smith <smithpb2250@gmail.com> wrote:
>
> On Thu, Mar 11, 2021 at 12:46 PM Peter Smith <smithpb2250@gmail.com> wrote:
> >
> > Please find attached the latest patch set v57*
> >
> > Differences from v56* are:
> >
> > * Rebased to HEAD @ today
> >
> > * Addresses the following feedback issues:
> >
> > (24) [vc-0305] Done. Ran pgindent for all patch 0001 source files.
> >
> > (49) [ak-0308] Fixed. In apply_handle_begion_prepare, don't set
> > in_remote_transaction if psf spooling
> >
> > (50) [ak-0308] Fixed. In apply_handle_prepare, assert
> > !in_remote_transaction if psf spooling.
> >
> > (52) [vc-0309] Done. Patch 0002. Simplify the way test 020 creates the
> > publication.
> >
> > (53) [vc-0309] Done. Patch 0002. Simplify the way test 022 creates the
> > publication.
> >
> > -----
> > [vc-0305] https://www.postgresql.org/message-id/CALDaNm1rRG2EUus%2BmFrqRzEshZwJZtxja0rn_n3qXGAygODfOA%40mail.gmail.com
> > [vc-0309] https://www.postgresql.org/message-id/CALDaNm0QuncAis5OqtjzOxAPTZRn545JLqfjFEJwyRjUH-XvEw%40mail.gmail.com
> > [ak-0308] https://www.postgresql.org/message-id/CAA4eK1%2BoSUU77T92FueDJWsp%3DFjTroNaNC-K45Dgdr7f18aBFA%40mail.gmail.com
> >
> > Kind Regards,
> > Peter Smith.
> > Fujitsu Australia
>
> Oops. I posted the wrong patch set in my previous email.
>
> Here are the correct ones for v57*.

Thanks for the updated patch, few comments:
--- a/src/backend/commands/subscriptioncmds.c
+++ b/src/backend/commands/subscriptioncmds.c
@@ -67,7 +67,8 @@ parse_subscription_options(List *options,
                                                   char **synchronous_commit,
                                                   bool *refresh,
                                                   bool *binary_given,
bool *binary,
-                                                  bool
*streaming_given, bool *streaming)
+                                                  bool
*streaming_given, bool *streaming,
+                                                  bool
*twophase_given, bool *twophase)


I felt twophase_given can be a local variable, it need not be added as
a function parameter as it is not used outside the function.

The corresponding changes can be done here too:
@@ -358,6 +402,8 @@ CreateSubscription(CreateSubscriptionStmt *stmt,
bool isTopLevel)
        bool            copy_data;
        bool            streaming;
        bool            streaming_given;
+       bool            twophase;
+       bool            twophase_given;
        char       *synchronous_commit;
        char       *conninfo;
        char       *slotname;
@@ -382,7 +428,8 @@ CreateSubscription(CreateSubscriptionStmt *stmt,
bool isTopLevel)
                                                           &synchronous_commit,
                                                           NULL,
 /* no "refresh" */

&binary_given, &binary,
-
&streaming_given, &streaming);
+
&streaming_given, &streaming,
+
&twophase_given, &twophase);


--- a/src/backend/replication/logical/worker.c
+++ b/src/backend/replication/logical/worker.c
@@ -2930,6 +2930,7 @@ maybe_reread_subscription(void)
                strcmp(newsub->slotname, MySubscription->slotname) != 0 ||
                newsub->binary != MySubscription->binary ||
                newsub->stream != MySubscription->stream ||
+               newsub->twophase != MySubscription->twophase ||
                !equal(newsub->publications, MySubscription->publications))
I think this is not possible, should this be an assert.

@@ -252,6 +254,16 @@ parse_output_parameters(List *options, uint32
*protocol_version,

                        *enable_streaming = defGetBoolean(defel);
                }
+               else if (strcmp(defel->defname, "two_phase") == 0)
+               {
+                       if (twophase_given)
+                               ereport(ERROR,
+                                               (errcode(ERRCODE_SYNTAX_ERROR),
+                                                errmsg("conflicting
or redundant options")));
+                       twophase_given = true;
+
+                       *enable_twophase = defGetBoolean(defel);
+               }

We have the following check in parse_subscription_options:
if (twophase && *twophase_given && *twophase)
{
if (streaming && *streaming_given && *streaming)
ereport(ERROR,
(errcode(ERRCODE_SYNTAX_ERROR),
errmsg("%s and %s are mutually exclusive options",
"two_phase = true", "streaming = true")));
}
Should we have a similar check in parse_output_parameters.

Regards,
Vignesh

Commits

  1. Add prepare API support for streaming transactions in logical replication.

  2. Doc: minor improvements for logical replication protocol documentation.

  3. Fix test failure in 021_twophase.pl.

  4. Refactor to make common functions in proto.c and worker.c.

  5. Unify PostgresNode's new() and get_new_node() methods

  6. Fix potential buffer overruns in proto.c.

  7. Add support for prepared transactions to built-in logical replication.

  8. Refactor function parse_subscription_options.

  9. Allow enabling two-phase option via replication protocol.

  10. Don't use Asserts to check for violations of replication protocol.

  11. Improve psql tab completion for options of subcriptions and publications

  12. Rearrange logrep worker's snapshot handling some more.

  13. doc: Update information of new messages for logical replication.

  14. ALTER SUBSCRIPTION ... ADD/DROP PUBLICATION

  15. Allow pgoutput to send logical decoding messages.

  16. Refactor function parse_output_parameters.

  17. Avoid repeated decoding of prepared transactions after a restart.

  18. Fix an oversight in ReorderBufferFinishPrepared.

  19. Allow multiple xacts during table sync in logical replication.

  20. Fix replication of in-progress transactions in tablesync worker.

  21. Fix 'skip-empty-xacts' option in test_decoding for streaming mode.

  22. Use Enum for top level logical replication message types.

  23. Add support for streaming to built-in logical replication.

  24. Fix the logical streaming test.

  25. Implement streaming mode in ReorderBuffer.

  26. Extend the logical decoding output plugin API with stream methods.

  27. Store 2PC GID in commit/abort WAL recs for logical decoding