Add a function to delete shard metadata from MX nodes

src/backend/distributed/metadata/metadata_sync.c

@@ -513,7 +513,7 @@ TableOwnerResetCommand(Oid relationId)
 
 
 /*
- * ShardListInsertCommand generates a singe command that can be
+ * ShardListInsertCommand generates a single command that can be
  * executed to replicate shard and shard placement metadata for the
  * given shard intervals. The function assumes that each shard has a
  * single placement, and asserts this information.
@@ -634,6 +634,37 @@ ShardListInsertCommand(List *shardIntervalList)
 }
 
 
+/*
+ * ShardListDeleteCommand generates a command list that can be executed to delete
+ * shard and shard placement metadata for the given shard.
+ */
+List *
+ShardDeleteCommandList(ShardInterval *shardInterval)
+{
+	uint64 shardId = shardInterval->shardId;
+	List *commandList = NIL;
+	StringInfo deletePlacementCommand = NULL;
+	StringInfo deleteShardCommand = NULL;
+
+	/* create command to delete shard placements */
+	deletePlacementCommand = makeStringInfo();
+	appendStringInfo(deletePlacementCommand,
+					 "DELETE FROM pg_dist_shard_placement WHERE shardid = %lu",
+					 shardId);
+
+	commandList = lappend(commandList, deletePlacementCommand->data);
+
+	/* create command to delete shard */
+	deleteShardCommand = makeStringInfo();
+	appendStringInfo(deleteShardCommand,
+					 "DELETE FROM pg_dist_shard WHERE shardid = %lu", shardId);
+
+	commandList = lappend(commandList, deleteShardCommand->data);
+
+	return commandList;
+}
+
+
 /*
  * NodeDeleteCommand generate a command that can be
  * executed to delete the metadata for a worker node.

src/include/distributed/metadata_sync.h

@@ -28,6 +28,7 @@ extern char * DistributionDeleteCommand(char *schemaName,
 extern char * TableOwnerResetCommand(Oid distributedRelationId);
 extern char * NodeListInsertCommand(List *workerNodeList);
 extern List * ShardListInsertCommand(List *shardIntervalList);
+extern List * ShardDeleteCommandList(ShardInterval *shardInterval);
 extern char * NodeDeleteCommand(uint32 nodeId);
 extern char * ColocationIdUpdateCommand(Oid relationId, uint32 colocationId);
 extern char * CreateSchemaDDLCommand(Oid schemaId);