Fix crash in citus_copy_shard_placement

src/backend/distributed/operations/repair_shards.c

@@ -74,6 +74,8 @@ static void VerifyTablesHaveReplicaIdentity(List *colocatedTableList);
 static bool RelationCanPublishAllModifications(Oid relationId);
 static bool CanUseLogicalReplication(Oid relationId, char shardReplicationMode);
 static void ErrorIfTableCannotBeReplicated(Oid relationId);
+static void ErrorIfTargetNodeIsNotSafeToCopyTo(const char *targetNodeName,
+											   int targetNodePort);
 static void RepairShardPlacement(int64 shardId, const char *sourceNodeName,
 								 int32 sourceNodePort, const char *targetNodeName,
 								 int32 targetNodePort);
@@ -183,6 +185,7 @@ citus_copy_shard_placement(PG_FUNCTION_ARGS)
 
 	ShardInterval *shardInterval = LoadShardInterval(shardId);
 	ErrorIfTableCannotBeReplicated(shardInterval->relationId);
+	ErrorIfTargetNodeIsNotSafeToCopyTo(targetNodeName, targetNodePort);
 
 	AcquirePlacementColocationLock(shardInterval->relationId, ExclusiveLock,
 								   doRepair ? "repair" : "copy");
@@ -789,6 +792,41 @@ ErrorIfTableCannotBeReplicated(Oid relationId)
 }
 
 
+/*
+ * ErrorIfTargetNodeIsNotSafeToCopyTo throws an error if the target node is not
+ * eligible for copying shards.
+ */
+static void
+ErrorIfTargetNodeIsNotSafeToCopyTo(const char *targetNodeName, int targetNodePort)
+{
+	WorkerNode *workerNode = FindWorkerNode(targetNodeName, targetNodePort);
+	if (workerNode == NULL)
+	{
+		ereport(ERROR, (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+						errmsg("Copying shards to a non-existing node is not supported"),
+						errhint(
+							"Add the target node via SELECT citus_add_node('%s', %d);",
+							targetNodeName, targetNodePort)));
+	}
+
+	if (!workerNode->isActive)
+	{
+		ereport(ERROR, (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+						errmsg("Copying shards to a non-active node is not supported"),
+						errhint(
+							"Activate the target node via SELECT citus_activate_node('%s', %d);",
+							targetNodeName, targetNodePort)));
+	}
+
+	if (!NodeIsPrimary(workerNode))
+	{
+		ereport(ERROR, (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+						errmsg("Copying shards to a secondary (e.g., replica) node is "
+							   "not supported")));
+	}
+}
+
+
 /*
  * LookupShardTransferMode maps the oids of citus.shard_transfer_mode enum
  * values to a char.

src/test/regress/expected/multi_replicate_reference_table.out

@@ -781,7 +781,51 @@ SELECT create_reference_table('ref_table');
 (1 row)
 
 INSERT INTO ref_table SELECT * FROM generate_series(1, 10);
-SELECT 1 FROM master_add_node('localhost', :worker_2_port);
+-- verify direct call to citus_copy_shard_placement errors if target node is not yet added
+SELECT citus_copy_shard_placement(
+           (SELECT shardid FROM pg_dist_shard WHERE logicalrelid='ref_table'::regclass::oid),
+           'localhost', :worker_1_port,
+           'localhost', :worker_2_port,
+           do_repair := false,
+           transfer_mode := 'block_writes');
+ERROR:  Copying shards to a non-existing node is not supported
+HINT:  Add the target node via SELECT citus_add_node('localhost', 57638);
+-- verify direct call to citus_copy_shard_placement errors if target node is secondary
+SELECT citus_add_secondary_node('localhost', :worker_2_port, 'localhost', :worker_1_port);
+ citus_add_secondary_node
+---------------------------------------------------------------------
+                  1370012
+(1 row)
+
+SELECT citus_copy_shard_placement(
+           (SELECT shardid FROM pg_dist_shard WHERE logicalrelid='ref_table'::regclass::oid),
+           'localhost', :worker_1_port,
+           'localhost', :worker_2_port,
+           do_repair := false,
+           transfer_mode := 'block_writes');
+ERROR:  Copying shards to a secondary (e.g., replica) node is not supported
+SELECT citus_remove_node('localhost', :worker_2_port);
+ citus_remove_node
+---------------------------------------------------------------------
+
+(1 row)
+
+-- verify direct call to citus_copy_shard_placement errors if target node is inactive
+SELECT 1 FROM master_add_inactive_node('localhost', :worker_2_port);
+ ?column?
+---------------------------------------------------------------------
+        1
+(1 row)
+
+SELECT citus_copy_shard_placement(
+           (SELECT shardid FROM pg_dist_shard WHERE logicalrelid='ref_table'::regclass::oid),
+           'localhost', :worker_1_port,
+           'localhost', :worker_2_port,
+           do_repair := false,
+           transfer_mode := 'block_writes');
+ERROR:  Copying shards to a non-active node is not supported
+HINT:  Activate the target node via SELECT citus_activate_node('localhost', 57638);
+SELECT 1 FROM master_activate_node('localhost', :worker_2_port);
  ?column?
 ---------------------------------------------------------------------
         1

src/test/regress/sql/multi_replicate_reference_table.sql

@@ -509,7 +509,34 @@ CREATE TABLE ref_table(a int);
 SELECT create_reference_table('ref_table');
 INSERT INTO ref_table SELECT * FROM generate_series(1, 10);
 
-SELECT 1 FROM master_add_node('localhost', :worker_2_port);
+-- verify direct call to citus_copy_shard_placement errors if target node is not yet added
+SELECT citus_copy_shard_placement(
+           (SELECT shardid FROM pg_dist_shard WHERE logicalrelid='ref_table'::regclass::oid),
+           'localhost', :worker_1_port,
+           'localhost', :worker_2_port,
+           do_repair := false,
+           transfer_mode := 'block_writes');
+
+-- verify direct call to citus_copy_shard_placement errors if target node is secondary
+SELECT citus_add_secondary_node('localhost', :worker_2_port, 'localhost', :worker_1_port);
+SELECT citus_copy_shard_placement(
+           (SELECT shardid FROM pg_dist_shard WHERE logicalrelid='ref_table'::regclass::oid),
+           'localhost', :worker_1_port,
+           'localhost', :worker_2_port,
+           do_repair := false,
+           transfer_mode := 'block_writes');
+SELECT citus_remove_node('localhost', :worker_2_port);
+
+-- verify direct call to citus_copy_shard_placement errors if target node is inactive
+SELECT 1 FROM master_add_inactive_node('localhost', :worker_2_port);
+SELECT citus_copy_shard_placement(
+           (SELECT shardid FROM pg_dist_shard WHERE logicalrelid='ref_table'::regclass::oid),
+           'localhost', :worker_1_port,
+           'localhost', :worker_2_port,
+           do_repair := false,
+           transfer_mode := 'block_writes');
+
+SELECT 1 FROM master_activate_node('localhost', :worker_2_port);
 
 -- verify we cannot replicate reference tables in a transaction modifying pg_dist_node
 BEGIN;