1 files changed, 42 insertions, 2 deletions

diff --git a/src/backend/replication/pgoutput/pgoutput.c b/src/backend/replication/pgoutput/pgoutput.c
index 2ea540ce4d2..ff9cf5d406d 100644
--- a/src/backend/replication/pgoutput/pgoutput.c
+++ b/src/backend/replication/pgoutput/pgoutput.c
@@ -70,6 +70,7 @@ static void publication_invalidation_cb(Datum arg, int cacheid,
 										uint32 hashvalue);
 static void send_relation_and_attrs(Relation relation, TransactionId xid,
 									LogicalDecodingContext *ctx);
+static void update_replication_progress(LogicalDecodingContext *ctx);
 
 /*
  * Entry in the map used to remember which relation schemas we sent.
@@ -381,7 +382,7 @@ static void
 pgoutput_commit_txn(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 					XLogRecPtr commit_lsn)
 {
-	OutputPluginUpdateProgress(ctx);
+	update_replication_progress(ctx);
 
 	OutputPluginPrepareWrite(ctx, true);
 	logicalrep_write_commit(ctx->out, txn, commit_lsn);
@@ -535,6 +536,8 @@ pgoutput_change(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 	TransactionId xid = InvalidTransactionId;
 	Relation	ancestor = NULL;
 
+	update_replication_progress(ctx);
+
 	if (!is_publishable_relation(relation))
 		return;
 
@@ -677,6 +680,8 @@ pgoutput_truncate(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 	Oid		   *relids;
 	TransactionId xid = InvalidTransactionId;
 
+	update_replication_progress(ctx);
+
 	/* Remember the xid for the change in streaming mode. See pgoutput_change. */
 	if (in_streaming)
 		xid = change->txn->xid;
@@ -735,6 +740,8 @@ pgoutput_message(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 	PGOutputData *data = (PGOutputData *) ctx->output_plugin_private;
 	TransactionId xid = InvalidTransactionId;
 
+	update_replication_progress(ctx);
+
 	if (!data->messages)
 		return;
 
@@ -921,7 +928,7 @@ pgoutput_stream_commit(struct LogicalDecodingContext *ctx,
 	Assert(!in_streaming);
 	Assert(rbtxn_is_streamed(txn));
 
-	OutputPluginUpdateProgress(ctx);
+	update_replication_progress(ctx);
 
 	OutputPluginPrepareWrite(ctx, true);
 	logicalrep_write_stream_commit(ctx->out, txn, commit_lsn);
@@ -1304,3 +1311,36 @@ rel_sync_cache_publication_cb(Datum arg, int cacheid, uint32 hashvalue)
 		entry->pubactions.pubtruncate = false;
 	}
 }
+
+/*
+ * Try to update progress and send a keepalive message if too many changes were
+ * processed.
+ *
+ * For a large transaction, if we don't send any change to the downstream for a
+ * long time (exceeds the wal_receiver_timeout of standby) then it can timeout.
+ * This can happen when all or most of the changes are not published.
+ */
+static void
+update_replication_progress(LogicalDecodingContext *ctx)
+{
+	static int	changes_count = 0;
+
+	/*
+	 * We don't want to try sending a keepalive message after processing each
+	 * change as that can have overhead. Tests revealed that there is no
+	 * noticeable overhead in doing it after continuously processing 100 or so
+	 * changes.
+	 */
+#define CHANGES_THRESHOLD 100
+
+	/*
+	 * If we are at the end of transaction LSN, update progress tracking.
+	 * Otherwise, after continuously processing CHANGES_THRESHOLD changes, we
+	 * try to send a keepalive message if required.
+	 */
+	if (ctx->end_xact || ++changes_count >= CHANGES_THRESHOLD)
+	{
+		OutputPluginUpdateProgress(ctx);
+		changes_count = 0;
+	}
+}