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| author | Amit Kapila <akapila@postgresql.org> | 2024-03-08 08:10:45 +0530 |
|---|---|---|
| committer | Amit Kapila <akapila@postgresql.org> | 2024-03-08 08:10:45 +0530 |
| commit | bf279ddd1c28ce0251446ee90043a4cb96e5db0f (patch) | |
| tree | 642eb01435995795793fc61cedcc66949c824f1d /src/backend/replication/logical/slotsync.c | |
| parent | 453c46873774219243501b8efc16b2b5a5e9d194 (diff) | |
| download | postgresql-bf279ddd1c28ce0251446ee90043a4cb96e5db0f.tar.gz postgresql-bf279ddd1c28ce0251446ee90043a4cb96e5db0f.zip | |
Introduce a new GUC 'standby_slot_names'.
This patch provides a way to ensure that physical standbys that are
potential failover candidates have received and flushed changes before
the primary server making them visible to subscribers. Doing so guarantees
that the promoted standby server is not lagging behind the subscribers
when a failover is necessary.
The logical walsender now guarantees that all local changes are sent and
flushed to the standby servers corresponding to the replication slots
specified in 'standby_slot_names' before sending those changes to the
subscriber.
Additionally, the SQL functions pg_logical_slot_get_changes,
pg_logical_slot_peek_changes and pg_replication_slot_advance are modified
to ensure that they process changes for failover slots only after physical
slots specified in 'standby_slot_names' have confirmed WAL receipt for those.
Author: Hou Zhijie and Shveta Malik
Reviewed-by: Masahiko Sawada, Peter Smith, Bertrand Drouvot, Ajin Cherian, Nisha Moond, Amit Kapila
Discussion: https://postgr.es/m/514f6f2f-6833-4539-39f1-96cd1e011f23@enterprisedb.com
Diffstat (limited to 'src/backend/replication/logical/slotsync.c')
| -rw-r--r-- | src/backend/replication/logical/slotsync.c | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c index ad0fc6a04b6..5074c8409f7 100644 --- a/src/backend/replication/logical/slotsync.c +++ b/src/backend/replication/logical/slotsync.c @@ -488,6 +488,10 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid) latestFlushPtr = GetStandbyFlushRecPtr(NULL); if (remote_slot->confirmed_lsn > latestFlushPtr) { + /* + * Can get here only if GUC 'standby_slot_names' on the primary server + * was not configured correctly. + */ ereport(AmLogicalSlotSyncWorkerProcess() ? LOG : ERROR, errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), errmsg("skipping slot synchronization as the received slot sync" @@ -857,6 +861,13 @@ validate_remote_info(WalReceiverConn *wrconn) remote_in_recovery = DatumGetBool(slot_getattr(tupslot, 1, &isnull)); Assert(!isnull); + /* + * Slot sync is currently not supported on a cascading standby. This is + * because if we allow it, the primary server needs to wait for all the + * cascading standbys, otherwise, logical subscribers can still be ahead + * of one of the cascading standbys which we plan to promote. Thus, to + * avoid this additional complexity, we restrict it for the time being. + */ if (remote_in_recovery) ereport(ERROR, errcode(ERRCODE_FEATURE_NOT_SUPPORTED), |