From f0043b64a17382e340bed5c61ec0025d0af34379 Mon Sep 17 00:00:00 2001
From: Karina <55838532+Green-Chan@users.noreply.github.com>
Date: Thu, 7 Mar 2024 13:08:19 +0300
Subject: [PATCH] Fix server crash when trying to execute
 activate_node_snapshot() on a single-node cluster (#7552)

This fixes #7551 reported by Egor Chindyaskin

Function activate_node_snapshot() is not meant to be called on a cluster
without worker nodes. This commit adds ERROR report for such case to
prevent server crash.
---
 src/backend/distributed/test/metadata_sync.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/src/backend/distributed/test/metadata_sync.c b/src/backend/distributed/test/metadata_sync.c
index dec20c772..ce025cff9 100644
--- a/src/backend/distributed/test/metadata_sync.c
+++ b/src/backend/distributed/test/metadata_sync.c
@@ -50,6 +50,13 @@ activate_node_snapshot(PG_FUNCTION_ARGS)
 	 * so we are using first primary worker node just for test purposes.
 	 */
 	WorkerNode *dummyWorkerNode = GetFirstPrimaryWorkerNode();
+	if (dummyWorkerNode == NULL)
+	{
+		ereport(ERROR, (errmsg("no worker nodes found"),
+						errdetail("Function activate_node_snapshot is meant to be "
+								  "used when running tests on a multi-node cluster "
+								  "with workers.")));
+	}
 
 	/*
 	 * Create MetadataSyncContext which is used throughout nodes' activation.