From fd5a1a0c3e566f7fc860838084466a1c25944281 Mon Sep 17 00:00:00 2001 From: Amit Kapila Date: Mon, 4 Aug 2025 04:02:47 +0000 Subject: Detect and report update_deleted conflicts. This enhancement builds upon the infrastructure introduced in commit 228c370868, which enables the preservation of deleted tuples and their origin information on the subscriber. This capability is crucial for handling concurrent transactions replicated from remote nodes. The update introduces support for detecting update_deleted conflicts during the application of update operations on the subscriber. When an update operation fails to locate the target row-typically because it has been concurrently deleted-we perform an additional table scan. This scan uses the SnapshotAny mechanism and we do this additional scan only when the retain_dead_tuples option is enabled for the relevant subscription. The goal of this scan is to locate the most recently deleted tuple-matching the old column values from the remote update-that has not yet been removed by VACUUM and is still visible according to our slot (i.e., its deletion is not older than conflict-detection-slot's xmin). If such a tuple is found, the system reports an update_deleted conflict, including the origin and transaction details responsible for the deletion. This provides a groundwork for more robust and accurate conflict resolution process, preventing unexpected behavior by correctly identifying cases where a remote update clashes with a deletion from another origin. Author: Zhijie Hou Reviewed-by: shveta malik Reviewed-by: Nisha Moond Reviewed-by: Dilip Kumar Reviewed-by: Hayato Kuroda Reviewed-by: Amit Kapila Discussion: https://postgr.es/m/OS0PR01MB5716BE80DAEB0EE2A6A5D1F5949D2@OS0PR01MB5716.jpnprd01.prod.outlook.com --- src/backend/utils/adt/pgstatfuncs.c | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-) (limited to 'src/backend/utils/adt/pgstatfuncs.c') diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c index 1c12ddbae49..c756c2bebaa 100644 --- a/src/backend/utils/adt/pgstatfuncs.c +++ b/src/backend/utils/adt/pgstatfuncs.c @@ -2171,7 +2171,7 @@ pg_stat_get_replication_slot(PG_FUNCTION_ARGS) Datum pg_stat_get_subscription_stats(PG_FUNCTION_ARGS) { -#define PG_STAT_GET_SUBSCRIPTION_STATS_COLS 11 +#define PG_STAT_GET_SUBSCRIPTION_STATS_COLS 12 Oid subid = PG_GETARG_OID(0); TupleDesc tupdesc; Datum values[PG_STAT_GET_SUBSCRIPTION_STATS_COLS] = {0}; @@ -2197,15 +2197,17 @@ pg_stat_get_subscription_stats(PG_FUNCTION_ARGS) INT8OID, -1, 0); TupleDescInitEntry(tupdesc, (AttrNumber) 6, "confl_update_exists", INT8OID, -1, 0); - TupleDescInitEntry(tupdesc, (AttrNumber) 7, "confl_update_missing", + TupleDescInitEntry(tupdesc, (AttrNumber) 7, "confl_update_deleted", INT8OID, -1, 0); - TupleDescInitEntry(tupdesc, (AttrNumber) 8, "confl_delete_origin_differs", + TupleDescInitEntry(tupdesc, (AttrNumber) 8, "confl_update_missing", INT8OID, -1, 0); - TupleDescInitEntry(tupdesc, (AttrNumber) 9, "confl_delete_missing", + TupleDescInitEntry(tupdesc, (AttrNumber) 9, "confl_delete_origin_differs", INT8OID, -1, 0); - TupleDescInitEntry(tupdesc, (AttrNumber) 10, "confl_multiple_unique_conflicts", + TupleDescInitEntry(tupdesc, (AttrNumber) 10, "confl_delete_missing", INT8OID, -1, 0); - TupleDescInitEntry(tupdesc, (AttrNumber) 11, "stats_reset", + TupleDescInitEntry(tupdesc, (AttrNumber) 11, "confl_multiple_unique_conflicts", + INT8OID, -1, 0); + TupleDescInitEntry(tupdesc, (AttrNumber) 12, "stats_reset", TIMESTAMPTZOID, -1, 0); BlessTupleDesc(tupdesc); -- cgit v1.2.3