import pytest import time import os, sys sys.path.insert(0, os.path.dirname(os.path.dirname(os.path.abspath(__file__)))) import helpers from helpers.cluster import ClickHouseCluster from helpers.network import PartitionManager cluster = ClickHouseCluster(__file__) # Cluster with 2 shards of 2 replicas each. node_1_1 is the instance with Distributed table. # Thus we have a shard with a local replica and a shard with remote replicas. node_1_1 = instance_with_dist_table = cluster.add_instance( 'node_1_1', with_zookeeper=True, main_configs=['configs/remote_servers.xml']) node_1_2 = cluster.add_instance('node_1_2', with_zookeeper=True) node_2_1 = cluster.add_instance('node_2_1', with_zookeeper=True) node_2_2 = cluster.add_instance('node_2_2', with_zookeeper=True) @pytest.fixture(scope="module") def started_cluster(): try: cluster.start() for shard in (1, 2): for replica in (1, 2): node = cluster.instances['node_{}_{}'.format(shard, replica)] node.query(''' CREATE TABLE replicated (d Date, x UInt32) ENGINE = ReplicatedMergeTree('/clickhouse/tables/{shard}/replicated', '{instance}', d, d, 8192)''' .format(shard=shard, instance=node.name)) node_1_1.query( "CREATE TABLE distributed (d Date, x UInt32) ENGINE = " "Distributed('test_cluster', 'default', 'replicated')") yield cluster finally: cluster.shutdown() def test(started_cluster): with PartitionManager() as pm: # Hinder replication between replicas of the same shard, but leave the possibility of distributed connection. pm.partition_instances(node_1_1, node_1_2, port=9009) pm.partition_instances(node_2_1, node_2_2, port=9009) node_1_2.query("INSERT INTO replicated VALUES ('2017-05-08', 1)") node_2_2.query("INSERT INTO replicated VALUES ('2017-05-08', 2)") time.sleep(1) # accrue replica delay assert node_1_1.query("SELECT sum(x) FROM replicated").strip() == '' assert node_1_2.query("SELECT sum(x) FROM replicated").strip() == '1' assert node_2_1.query("SELECT sum(x) FROM replicated").strip() == '' assert node_2_2.query("SELECT sum(x) FROM replicated").strip() == '2' # With in_order balancing first replicas chosen. assert instance_with_dist_table.query( "SELECT count() FROM distributed SETTINGS load_balancing='in_order'").strip() == '' # When we set max_replica_delay, first replicas must be excluded. assert instance_with_dist_table.query(''' SELECT sum(x) FROM distributed SETTINGS load_balancing='in_order', max_replica_delay_for_distributed_queries=1 ''').strip() == '3' pm.drop_instance_zk_connections(node_1_2) pm.drop_instance_zk_connections(node_2_2) time.sleep(4) # allow pings to zookeeper to timeout (must be greater than ZK session timeout). # At this point all replicas are stale, but the query must still go to second replicas which are the least stale ones. assert instance_with_dist_table.query(''' SELECT sum(x) FROM distributed SETTINGS load_balancing='in_order', max_replica_delay_for_distributed_queries=1 ''').strip() == '3' # If we forbid stale replicas, the query must fail. with pytest.raises(Exception): print instance_with_dist_table.query(''' SELECT count() FROM distributed SETTINGS load_balancing='in_order', max_replica_delay_for_distributed_queries=1, fallback_to_stale_replicas_for_distributed_queries=0 ''')