From: Peter Eisentraut <peter_e@gmx.net>
Date: Mon, 30 Apr 2018 17:49:20 +0000 (-0400)
Subject: Don't do logical replication of TRUNCATE of zero tables
X-Git-Tag: REL_11_BETA1~140
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=92e1583b439ffab1d20419998895932e4fbe32fd;p=thirdparty%2Fpostgresql.git

Don't do logical replication of TRUNCATE of zero tables

When due to publication configuration, a TRUNCATE change ends up with
zero tables to be published, don't send the message out, just skip it.
It's not wrong, but obviously useless overhead.
---

diff --git a/src/backend/replication/pgoutput/pgoutput.c b/src/backend/replication/pgoutput/pgoutput.c
index a3e5300679f..86e0951a700 100644
--- a/src/backend/replication/pgoutput/pgoutput.c
+++ b/src/backend/replication/pgoutput/pgoutput.c
@@ -407,13 +407,16 @@ pgoutput_truncate(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 		maybe_send_schema(ctx, relation, relentry);
 	}
 
-	OutputPluginPrepareWrite(ctx, true);
-	logicalrep_write_truncate(ctx->out,
-							  nrelids,
-							  relids,
-							  change->data.truncate.cascade,
-							  change->data.truncate.restart_seqs);
-	OutputPluginWrite(ctx, true);
+	if (nrelids > 0)
+	{
+		OutputPluginPrepareWrite(ctx, true);
+		logicalrep_write_truncate(ctx->out,
+								  nrelids,
+								  relids,
+								  change->data.truncate.cascade,
+								  change->data.truncate.restart_seqs);
+		OutputPluginWrite(ctx, true);
+	}
 
 	MemoryContextSwitchTo(old);
 	MemoryContextReset(data->context);