ClickHouse/tests/integration/test_always_fetch_merged/test.py

import pytest
import time
from helpers.cluster import ClickHouseCluster
from helpers.test_tools import assert_eq_with_retry


cluster = ClickHouseCluster(__file__)

node1 = cluster.add_instance('node1', with_zookeeper=True)
node2 = cluster.add_instance('node2', with_zookeeper=True)

@pytest.fixture(scope="module")
def started_cluster():
    try:
        cluster.start()

        yield cluster

    finally:
        cluster.shutdown()


def test_replica_always_download(started_cluster):
    node1.query("""
        CREATE TABLE test_table(
            key UInt64,
            value String
        ) ENGINE = ReplicatedMergeTree('/clickhouse/tables/test_table/replicated', '1')
        ORDER BY tuple()
    """)
    node2.query("""
        CREATE TABLE test_table(
            key UInt64,
            value String
        ) ENGINE = ReplicatedMergeTree('/clickhouse/tables/test_table/replicated', '2')
        ORDER BY tuple()
        SETTINGS always_fetch_merged_part=1
    """)

    # Stop merges on single node
    node1.query("SYSTEM STOP MERGES")

    for i in range(0, 10):
        node1.query("INSERT INTO test_table VALUES ({}, '{}')".format(i, i))

    assert node1.query("SELECT COUNT() FROM test_table") == "10\n"
    assert_eq_with_retry(node2, "SELECT COUNT() FROM test_table", "10\n")

    time.sleep(3)

    # Nothing is merged
    assert node1.query("SELECT COUNT() FROM system.parts WHERE table = 'test_table' and active=1") == "10\n"

    assert node2.query("SELECT COUNT() FROM system.parts WHERE table = 'test_table' and active=1") == "10\n"

    node1.query("SYSTEM START MERGES")

    time.sleep(3)

    node1_parts = node1.query("SELECT COUNT() FROM system.parts WHERE table = 'test_table' and active=1").strip()
    node2_parts = node2.query("SELECT COUNT() FROM system.parts WHERE table = 'test_table' and active=1").strip()
    assert int(node1_parts) < 10  # something merged
    assert int(node2_parts) < 10