dbms: FETCH PARTITION: development [#METR-13153].

dbms/include/DB/Core/ErrorCodes.h

@@ -264,6 +264,7 @@ namespace ErrorCodes
 		NO_ACTIVE_REPLICAS,
 		TOO_MUCH_RETRIES_TO_FETCH_PARTS,
 		PARTITION_ALREADY_EXISTS,
+		PARTITION_DOESNT_EXIST,
 
 		POCO_EXCEPTION = 1000,
 		STD_EXCEPTION,

dbms/src/Storages/MergeTree/ReplicatedMergeTreePartsExchange.cpp

@@ -73,7 +73,8 @@ MergeTreeData::MutableDataPartPtr ReplicatedMergeTreePartsFetcher::fetchPart(
 		std::make_pair("compress", "false")};
 	ReadBufferFromHTTP in(host, port, params);
 
-	String part_path = data.getFullPath() + (to_detached ? "detached/" : "") + "tmp_" + part_name + "/";
+	String full_part_name = String(to_detached ? "detached/" : "") + "tmp_" + part_name;
+	String part_path = data.getFullPath() + full_part_name + "/";
 	Poco::File part_file(part_path);
 
 	if (part_file.exists())
@@ -85,7 +86,7 @@ MergeTreeData::MutableDataPartPtr ReplicatedMergeTreePartsFetcher::fetchPart(
 	part_file.createDirectory();
 
 	MergeTreeData::MutableDataPartPtr new_data_part = std::make_shared<MergeTreeData::DataPart>(data);
-	new_data_part->name = "tmp_" + part_name;
+	new_data_part->name = full_part_name;
 	new_data_part->is_temp = true;
 
 	size_t files;

dbms/src/Storages/StorageReplicatedMergeTree.cpp

@@ -2945,6 +2945,9 @@ void StorageReplicatedMergeTree::fetchPartition(const Field & partition, bool un
 					parts_to_fetch_partition.push_back(part);
 
 			parts_to_fetch = std::move(parts_to_fetch_partition);
+
+			if (parts_to_fetch.empty())
+				throw Exception("Partition " + partition_str + " on " + best_replica_path + " doesn't exist", ErrorCodes::PARTITION_DOESNT_EXIST);
 		}
 		else
 		{