Horton

Re: Fix slot synchronization with two_phase decoding enabled

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: shveta malik <shveta.malik@gmail.com>
Cc: Nisha Moond <nisha.moond412@gmail.com>, Masahiko Sawada <sawada.mshk@gmail.com>, Amit Kapila <amit.kapila16@gmail.com>, "Zhijie Hou (Fujitsu)" <houzj.fnst@fujitsu.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2025-05-03T17:23:51Z
Lists: pgsql-hackers 
BF member mule just showed what seems an identical failure [1]:

2025-05-03 17:46:20.088 CEST [24308:3] LOG:  database system is ready to accept read-only connections
2025-05-03 17:46:20.091 CEST [24321:1] LOG:  slot sync worker started
2025-05-03 17:46:20.100 CEST [24322:1] LOG:  started streaming WAL from primary at 0/6000000 on timeline 1
2025-05-03 17:46:20.117 CEST [24321:2] LOG:  starting logical decoding for slot "lsub1_slot"
2025-05-03 17:46:20.117 CEST [24321:3] DETAIL:  Streaming transactions committing after 0/60049C8, reading WAL from 0/5000048.
2025-05-03 17:46:20.117 CEST [24321:4] LOG:  logical decoding found consistent point at 0/5000048
2025-05-03 17:46:20.117 CEST [24321:5] DETAIL:  There are no running transactions.
TRAP: failed Assert("slot->data.two_phase_at <= slot->data.confirmed_flush"), File: "slotsync.c", Line: 311, PID: 24321
postgres: standby1: slotsync worker (ExceptionalCondition+0x59)[0x556c3b8cb3e9]
postgres: standby1: slotsync worker (+0x4cb100)[0x556c3b706100]
postgres: standby1: slotsync worker (+0x4cba4c)[0x556c3b706a4c]
postgres: standby1: slotsync worker (ReplSlotSyncWorkerMain+0x258)[0x556c3b707598]
postgres: standby1: slotsync worker (postmaster_child_launch+0x102)[0x556c3b6d6962]
postgres: standby1: slotsync worker (+0x49daea)[0x556c3b6d8aea]
postgres: standby1: slotsync worker (+0x49fb3d)[0x556c3b6dab3d]
postgres: standby1: slotsync worker (PostmasterMain+0xd3f)[0x556c3b6dc04f]
postgres: standby1: slotsync worker (main+0x1ca)[0x556c3b3bee1a]
/lib/x86_64-linux-gnu/libc.so.6(+0x2724a)[0x7fe08da4824a]
/lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0x85)[0x7fe08da48305]
postgres: standby1: slotsync worker (_start+0x21)[0x556c3b3bf421]
2025-05-03 17:46:20.337 CEST [24308:4] LOG:  slot sync worker process (PID 24321) was terminated by signal 6: Aborted

			regards, tom lane

[1] https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=mule&dt=2025-05-03%2015%3A30%3A02

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.