v3-0001-Table-sync-missed-for-newly-added-tables-because-.patch

From cec60bbd7a6d1b66672c6969a11b89a8e18190c9 Mon Sep 17 00:00:00 2001
From: Vignesh C <vignesh21@gmail.com>
Date: Thu, 1 Feb 2024 09:46:40 +0530
Subject: [PATCH v3] Table sync missed for newly added tables because
 subscription relation cache invalidation was not handled in certain
 concurrent scenarios.

Table sync was missed if the invalidation of table sync occurs while
the non ready tables were getting prepared. This occurrs because
the table state was being set to valid at the end of non ready table
list preparation irrespective of any inavlidations occurred while
preparing the list. Fixed it by changing the boolean variable to an
tri-state enum and by setting table state to valid only if no
invalidations have been occurred while the list is being prepared.
---
 src/backend/replication/logical/tablesync.c | 25 +++++++++++++++++----
 src/tools/pgindent/typedefs.list            |  1 +
 2 files changed, 22 insertions(+), 4 deletions(-)

diff --git a/src/backend/replication/logical/tablesync.c b/src/backend/replication/logical/tablesync.c
index 5acab3f3e2..b38b0e3ba1 100644
--- a/src/backend/replication/logical/tablesync.c
+++ b/src/backend/replication/logical/tablesync.c
@@ -123,7 +123,14 @@
 #include "utils/syscache.h"
 #include "utils/usercontext.h"
 
-static bool table_states_valid = false;
+typedef enum
+{
+	SYNC_TABLE_STATE_NEEDS_REBUILD,
+	SYNC_TABLE_STATE_REBUILD_STARTED,
+	SYNC_TABLE_STATE_VALID,
+} SyncingTablesState;
+
+static SyncingTablesState table_states_valid = SYNC_TABLE_STATE_NEEDS_REBUILD;
 static List *table_states_not_ready = NIL;
 static bool FetchTableStates(bool *started_tx);
 
@@ -273,7 +280,7 @@ wait_for_worker_state_change(char expected_state)
 void
 invalidate_syncing_table_states(Datum arg, int cacheid, uint32 hashvalue)
 {
-	table_states_valid = false;
+	table_states_valid = SYNC_TABLE_STATE_NEEDS_REBUILD;
 }
 
 /*
@@ -1568,13 +1575,15 @@ FetchTableStates(bool *started_tx)
 
 	*started_tx = false;
 
-	if (!table_states_valid)
+	if (table_states_valid != SYNC_TABLE_STATE_VALID)
 	{
 		MemoryContext oldctx;
 		List	   *rstates;
 		ListCell   *lc;
 		SubscriptionRelState *rstate;
 
+		table_states_valid = SYNC_TABLE_STATE_REBUILD_STARTED;
+
 		/* Clean the old lists. */
 		list_free_deep(table_states_not_ready);
 		table_states_not_ready = NIL;
@@ -1608,7 +1617,15 @@ FetchTableStates(bool *started_tx)
 		has_subrels = (table_states_not_ready != NIL) ||
 			HasSubscriptionRelations(MySubscription->oid);
 
-		table_states_valid = true;
+		/*
+		 * If the subscription relation cache has been invalidated since we
+		 * entered this routine, we still use and return the relations we just
+		 * finished constructing, to avoid infinite loops, but we leave the
+		 * table states marked as stale so that we'll rebuild it again on next
+		 * access. Otherwise, we mark the table states as valid.
+		 */
+		if (table_states_valid == SYNC_TABLE_STATE_REBUILD_STARTED)
+			table_states_valid = SYNC_TABLE_STATE_VALID;
 	}
 
 	return has_subrels;
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index 91433d439b..5a40f549f9 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -2703,6 +2703,7 @@ SupportRequestSelectivity
 SupportRequestSimplify
 SupportRequestWFuncMonotonic
 Syn
+SyncingTablesState
 SyncOps
 SyncRepConfigData
 SyncRepStandbyData
-- 
2.34.1