]> git.ipfire.org Git - thirdparty/postgresql.git/commitdiff
Fix issues in logical replication sequence synchronization.
authorAmit Kapila <akapila@postgresql.org>
Mon, 27 Jul 2026 03:36:05 +0000 (09:06 +0530)
committerAmit Kapila <akapila@postgresql.org>
Mon, 27 Jul 2026 03:36:05 +0000 (09:06 +0530)
1. Stop a running sequence synchronization worker when
ALTER SUBSCRIPTION ... DISABLE is executed.  The worker did not reread its
subscription after starting a transaction, so it kept running with a stale
copy and missed the disable. It now calls maybe_reread_subscription()
after StartTransactionCommand(), matching the apply worker.

2. Restore the invariant that publisher-side synchronization slots are
dropped last during ALTER SUBSCRIPTION ... REFRESH PUBLICATION.  The
slot-drop loop now runs after the sequence-removal loop, so the
non-transactional slot drops happen only after all catalog changes that
could still be rolled back on error.

3. Restore psql tab completion for
ALTER SUBSCRIPTION ... REFRESH PUBLICATION WITH (.

4. Make pg_stat_subscription report NULL for the fields that do not apply
to a sequence synchronization worker, which does not stream from a
walsender, and update the documentation accordingly.

5. Update the pg_subscription_rel.srsublsn catalog documentation to
describe its semantics for sequence rows.

Reported-by: Noah Misch <noah@leadboat.com>
Author: vignesh C <vignesh21@gmail.com>
Reviewed-by: Hayato Kuroda <kuroda.hayato@fujitsu.com>
Reviewed-by: Amit Kapila <amit.kapila16@gmail.com>
Backpatch-through: 19, where it was introduced
Discussion: https://postgr.es/m/20260710045217.f0.noahmisch@microsoft.com

doc/src/sgml/catalogs.sgml
doc/src/sgml/monitoring.sgml
src/backend/commands/subscriptioncmds.c
src/backend/replication/logical/sequencesync.c
src/backend/replication/logical/worker.c
src/bin/psql/tab-complete.in.c

index 4b474c139174d79ce51b7fbcfd969f78d856138a..6066c4784f4bebe29ff31e6d73eb6eeb2e9f0a9f 100644 (file)
@@ -8893,7 +8893,11 @@ SCRAM-SHA-256$<replaceable>&lt;iteration count&gt;</replaceable>:<replaceable>&l
       <para>
        Remote LSN of the state change used for synchronization coordination
        when in <literal>s</literal> or <literal>r</literal> states,
-       otherwise null
+       otherwise null. For sequences, this instead holds the publisher
+       sequence's page LSN as of the last synchronization, which does not
+       track replication progress the way it does for tables; see
+       <xref linkend="sequences-out-of-sync"/> for how it is used to detect
+       out-of-sync sequences.
       </para></entry>
      </row>
     </tbody>
index 1ce0ef007998dec53b389c11e332979a1199e4fc..a209e891b181ac23f719304b5e5d362982eaf871 100644 (file)
@@ -2473,8 +2473,8 @@ description | Waiting for a newly initialized WAL file to reach durable storage
       </para>
       <para>
        Process ID of the leader apply worker if this process is a parallel
-       apply worker; NULL if this process is a leader apply worker or a table
-       synchronization worker
+       apply worker; NULL if this process is a leader apply worker, a table
+       synchronization worker or a sequence synchronization worker
       </para></entry>
      </row>
 
@@ -2484,7 +2484,8 @@ description | Waiting for a newly initialized WAL file to reach durable storage
       </para>
       <para>
        OID of the relation that the worker is synchronizing; NULL for the
-       leader apply worker and parallel apply workers
+       leader apply worker, parallel apply workers and the sequence
+       synchronization worker
       </para></entry>
      </row>
 
@@ -2494,7 +2495,8 @@ description | Waiting for a newly initialized WAL file to reach durable storage
       </para>
       <para>
        Last write-ahead log location received, the initial value of
-       this field being 0; NULL for parallel apply workers
+       this field being 0; NULL for parallel apply workers and the sequence
+       synchronization worker
       </para></entry>
      </row>
 
@@ -2504,7 +2506,7 @@ description | Waiting for a newly initialized WAL file to reach durable storage
       </para>
       <para>
        Send time of last message received from origin WAL sender; NULL for
-       parallel apply workers
+       parallel apply workers and the sequence synchronization worker
       </para></entry>
      </row>
 
@@ -2514,7 +2516,7 @@ description | Waiting for a newly initialized WAL file to reach durable storage
       </para>
       <para>
        Receipt time of last message received from origin WAL sender; NULL for
-       parallel apply workers
+       parallel apply workers and the sequence synchronization worker
       </para></entry>
      </row>
 
@@ -2524,7 +2526,7 @@ description | Waiting for a newly initialized WAL file to reach durable storage
       </para>
       <para>
        Last write-ahead log location reported to origin WAL sender; NULL for
-       parallel apply workers
+       parallel apply workers and the sequence synchronization worker
       </para></entry>
      </row>
 
@@ -2534,7 +2536,8 @@ description | Waiting for a newly initialized WAL file to reach durable storage
       </para>
       <para>
        Time of last write-ahead log location reported to origin WAL
-       sender; NULL for parallel apply workers
+       sender; NULL for parallel apply workers and the sequence synchronization
+       worker
       </para></entry>
      </row>
     </tbody>
index d4504b4a0c6fb90bda3c20b4445d1d009ffab4b6..013ac46db0725af63d9418b25e05c6cca682b667 100644 (file)
@@ -1288,34 +1288,6 @@ AlterSubscription_refresh(Subscription *sub, bool copy_data,
                        }
                }
 
-               /*
-                * Drop the tablesync slots associated with removed tables. This has
-                * to be at the end because otherwise if there is an error while doing
-                * the database operations we won't be able to rollback dropped slots.
-                */
-               foreach_ptr(SubRemoveRels, sub_remove_rel, sub_remove_rels)
-               {
-                       if (sub_remove_rel->state != SUBREL_STATE_READY &&
-                               sub_remove_rel->state != SUBREL_STATE_SYNCDONE)
-                       {
-                               char            syncslotname[NAMEDATALEN] = {0};
-
-                               /*
-                                * For READY/SYNCDONE states we know the tablesync slot has
-                                * already been dropped by the tablesync worker.
-                                *
-                                * For other states, there is no certainty, maybe the slot
-                                * does not exist yet. Also, if we fail after removing some of
-                                * the slots, next time, it will again try to drop already
-                                * dropped slots and fail. For these reasons, we allow
-                                * missing_ok = true for the drop.
-                                */
-                               ReplicationSlotNameForTablesync(sub->oid, sub_remove_rel->relid,
-                                                                                               syncslotname, sizeof(syncslotname));
-                               ReplicationSlotDropAtPubNode(wrconn, syncslotname, true);
-                       }
-               }
-
                /*
                 * Next remove state for sequences we should not care about anymore
                 * using the data we collected above
@@ -1343,6 +1315,34 @@ AlterSubscription_refresh(Subscription *sub, bool copy_data,
                                                                                sub->name));
                        }
                }
+
+               /*
+                * Drop the tablesync slots associated with removed tables. This has
+                * to be at the end because otherwise if there is an error while doing
+                * the database operations we won't be able to rollback dropped slots.
+                */
+               foreach_ptr(SubRemoveRels, sub_remove_rel, sub_remove_rels)
+               {
+                       if (sub_remove_rel->state != SUBREL_STATE_READY &&
+                               sub_remove_rel->state != SUBREL_STATE_SYNCDONE)
+                       {
+                               char            syncslotname[NAMEDATALEN] = {0};
+
+                               /*
+                                * For READY/SYNCDONE states we know the tablesync slot has
+                                * already been dropped by the tablesync worker.
+                                *
+                                * For other states, there is no certainty, maybe the slot
+                                * does not exist yet. Also, if we fail after removing some of
+                                * the slots, next time, it will again try to drop already
+                                * dropped slots and fail. For these reasons, we allow
+                                * missing_ok = true for the drop.
+                                */
+                               ReplicationSlotNameForTablesync(sub->oid, sub_remove_rel->relid,
+                                                                                               syncslotname, sizeof(syncslotname));
+                               ReplicationSlotDropAtPubNode(wrconn, syncslotname, true);
+                       }
+               }
        }
        PG_FINALLY();
        {
index d0370056de311b9d89ec8f36662b5746f7f9bfda..fe506a98c2052acf56d6eade7e200bb970c3f571 100644 (file)
@@ -495,6 +495,7 @@ copy_sequences(WalReceiverConn *conn)
                TupleTableSlot *slot;
 
                StartTransactionCommand();
+               maybe_reread_subscription();
 
                for (int idx = cur_batch_base_index; idx < n_seqinfos; idx++)
                {
@@ -724,6 +725,7 @@ LogicalRepSyncSequences(void)
        StringInfoData app_name;
 
        StartTransactionCommand();
+       maybe_reread_subscription();
 
        rel = table_open(SubscriptionRelRelationId, AccessShareLock);
 
index 0ff5cef63cddac0ca51a33164ae116c7655b97d4..0bd19074010d7ec19ec8896dcea047ee5ddd7034 100644 (file)
@@ -5985,8 +5985,18 @@ SetupApplyOrSyncWorker(int worker_slot)
         */
 
        /* Initialise stats to a sanish value */
-       MyLogicalRepWorker->last_send_time = MyLogicalRepWorker->last_recv_time =
-               MyLogicalRepWorker->reply_time = GetCurrentTimestamp();
+       if (am_sequencesync_worker())
+       {
+               MyLogicalRepWorker->last_send_time =
+                       MyLogicalRepWorker->last_recv_time =
+                       MyLogicalRepWorker->reply_time = 0;
+       }
+       else
+       {
+               MyLogicalRepWorker->last_send_time =
+                       MyLogicalRepWorker->last_recv_time =
+                       MyLogicalRepWorker->reply_time = GetCurrentTimestamp();
+       }
 
        /* Load the libpq-specific functions */
        load_file("libpqwalreceiver", false);
index 1cacc8c3ea2cc3fd9c752391521f6d85b53c189c..17dcabe755fb72ccd76f49b96ad22dcb4c4c3351 100644 (file)
@@ -2354,6 +2354,9 @@ match_previous_words(int pattern_id,
        /* ALTER SUBSCRIPTION <name> REFRESH */
        else if (Matches("ALTER", "SUBSCRIPTION", MatchAny, MatchAnyN, "REFRESH"))
                COMPLETE_WITH("PUBLICATION", "SEQUENCES");
+       /* ALTER SUBSCRIPTION <name> REFRESH PUBLICATION */
+       else if (Matches("ALTER", "SUBSCRIPTION", MatchAny, MatchAnyN, "REFRESH", "PUBLICATION"))
+               COMPLETE_WITH("WITH (");
        /* ALTER SUBSCRIPTION <name> REFRESH PUBLICATION WITH ( */
        else if (Matches("ALTER", "SUBSCRIPTION", MatchAny, MatchAnyN, "REFRESH", "PUBLICATION", "WITH", "("))
                COMPLETE_WITH("copy_data");