Horton

Re: Fix slot synchronization with two_phase decoding enabled

shveta malik <shveta.malik@gmail.com>

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From: shveta malik <shveta.malik@gmail.com>
To: Nisha Moond <nisha.moond412@gmail.com>
Cc: Amit Kapila <amit.kapila16@gmail.com>, Masahiko Sawada <sawada.mshk@gmail.com>, "Zhijie Hou (Fujitsu)" <houzj.fnst@fujitsu.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, shveta malik <shveta.malik@gmail.com>
Date: 2025-04-24T10:27:22Z
Lists: pgsql-hackers 
On Thu, Apr 24, 2025 at 2:54 PM Nisha Moond <nisha.moond412@gmail.com> wrote:
>
> Please find the updated patch for Approach 3, which implements the
> idea suggested by Swada-san above.
>

Thank You for the patch.

1)

CreateDecodingContext:

  if (ctx->twophase && !slot->data.two_phase)
  {
+ /*
+ * Do not allow two-phase decoding for failover enabled slots.
+ *
+ * See comments atop the similar check in ReplicationSlotCreate() for
+ * a detailed reason.
+ */
+ if (slot->data.failover)
+ ereport(ERROR,
+ (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+ errmsg("cannot enable two-phase decoding for failover enabled slot \"%s\"",
+ NameStr(slot->data.name))));
+

Can you please add tetscase to cover this scenario?

2)
We shall update create-sub documents as well for these mutually
exclusive options. Review other pages (alter-sub, create-slot) as well
for any required change.

3)
+##################################################
+# Test that the failover option can be enabled for a two_phase enabled
+# subscription.
+##################################################

Suggestion: 'Test that the failover option can be enabled for a two_phase
enabled subscription only through Alter Subscription (failover=true)'


thanks
Shveta

Commits

  1. Don't retreat slot's confirmed_flush LSN.

  2. Fix assertion failure during decoding from synced slots.

  3. Fix xmin advancement during fast_forward decoding.

  4. Fix slot synchronization for two_phase enabled slots.

  5. Again match pg_user_mappings to information_schema.user_mapping_options.