Fix version for parallel replication (#139)

Author: bakwc

mysql_ch_replicator/clickhouse_api.py

@@ -292,3 +292,25 @@ def get_system_setting(self, name):
         if not results:
             return None
         return results[0].get('value', None)
+
+    def get_max_record_version(self, table_name):
+        """
+        Query the maximum _version value for a given table directly from ClickHouse.
+        
+        Args:
+            table_name: The name of the table to query
+            
+        Returns:
+            The maximum _version value as an integer, or None if the table doesn't exist
+            or has no records
+        """
+        try:
+            query = f"SELECT MAX(_version) FROM `{self.database}`.`{table_name}`"
+            result = self.client.query(query)
+            if not result.result_rows or result.result_rows[0][0] is None:
+                logger.warning(f"No records with _version found in table {table_name}")
+                return None
+            return result.result_rows[0][0]
+        except Exception as e:
+            logger.error(f"Error querying max _version for table {table_name}: {e}")
+            return None

mysql_ch_replicator/db_replicator_initial.py

@@ -4,6 +4,7 @@
 import time
 import sys
 import subprocess
+import pickle
 from logging import getLogger
 from enum import Enum
 
@@ -213,6 +214,7 @@ def perform_initial_replication_table(self, table_name):
             f'replicated {stats_number_of_records} records, '
             f'primary key: {max_primary_key}',
         )
+        self.save_state_if_required(force=True)
 
     def perform_initial_replication_table_parallel(self, table_name):
         """
@@ -273,3 +275,28 @@ def perform_initial_replication_table_parallel(self, table_name):
             raise
 
         logger.info(f"All workers completed replication of table {table_name}")
+        
+        # Consolidate record versions from all worker states
+        logger.info(f"Consolidating record versions from worker states for table {table_name}")
+        self.consolidate_worker_record_versions(table_name)
+        
+    def consolidate_worker_record_versions(self, table_name):
+        """
+        Query ClickHouse directly to get the maximum record version for the specified table
+        and update the main state with this version.
+        """
+        logger.info(f"Getting maximum record version from ClickHouse for table {table_name}")
+        
+        # Query ClickHouse for the maximum record version
+        max_version = self.replicator.clickhouse_api.get_max_record_version(table_name)
+        
+        if max_version is not None and max_version > 0:
+            current_version = self.replicator.state.tables_last_record_version.get(table_name, 0)
+            if max_version > current_version:
+                logger.info(f"Updating record version for table {table_name} from {current_version} to {max_version}")
+                self.replicator.state.tables_last_record_version[table_name] = max_version
+                self.replicator.state.save()
+            else:
+                logger.info(f"Current version {current_version} is already up-to-date with ClickHouse version {max_version}")
+        else:
+            logger.warning(f"No record version found in ClickHouse for table {table_name}")

test_mysql_ch_replicator.py

@@ -574,6 +574,129 @@ def test_initial_only():
     db_replicator_runner.stop()
 
 
+def test_parallel_initial_replication_record_versions():
+    """
+    Test that record versions are properly consolidated from worker states
+    after parallel initial replication.
+    """
+    # Only run this test with parallel configuration
+    cfg_file = 'tests_config_parallel.yaml'
+    cfg = config.Settings()
+    cfg.load(cfg_file)
+    
+    # Ensure we have parallel replication configured
+    assert cfg.initial_replication_threads > 1, "This test requires initial_replication_threads > 1"
+    
+    mysql = mysql_api.MySQLApi(
+        database=None,
+        mysql_settings=cfg.mysql,
+    )
+
+    ch = clickhouse_api.ClickhouseApi(
+        database=TEST_DB_NAME,
+        clickhouse_settings=cfg.clickhouse,
+    )
+
+    prepare_env(cfg, mysql, ch)
+
+    # Create a table with sufficient records for parallel processing
+    mysql.execute(f'''
+CREATE TABLE `{TEST_TABLE_NAME}` (
+    id int NOT NULL AUTO_INCREMENT,
+    name varchar(255),
+    age int,
+    version int NOT NULL DEFAULT 1,
+    PRIMARY KEY (id)
+); 
+    ''')
+
+    # Insert a large number of records to ensure parallel processing
+    for i in range(1, 1001):
+        mysql.execute(
+            f"INSERT INTO `{TEST_TABLE_NAME}` (name, age, version) VALUES ('User{i}', {20+i%50}, {i});", 
+            commit=(i % 100 == 0)  # Commit every 100 records
+        )
+    
+    # Run initial replication only with parallel workers
+    db_replicator_runner = DbReplicatorRunner(TEST_DB_NAME, cfg_file=cfg_file)
+    db_replicator_runner.run()
+
+    assert_wait(lambda: TEST_DB_NAME in ch.get_databases(), max_wait_time=10.0)
+
+    ch.execute_command(f'USE `{TEST_DB_NAME}`')
+
+    assert_wait(lambda: TEST_TABLE_NAME in ch.get_tables(), max_wait_time=10.0)
+    assert_wait(lambda: len(ch.select(TEST_TABLE_NAME)) == 1000, max_wait_time=10.0)
+
+    db_replicator_runner.stop()
+
+    # Verify database and table were created
+    assert TEST_DB_NAME in ch.get_databases()
+    ch.execute_command(f'USE `{TEST_DB_NAME}`')
+    assert TEST_TABLE_NAME in ch.get_tables()
+    
+    # Verify all records were replicated
+    records = ch.select(TEST_TABLE_NAME)
+    assert len(records) == 1000
+    
+    # Instead of reading the state file directly, verify the record versions are correctly handled
+    # by checking the max _version in the ClickHouse table
+    versions_query = ch.query(f"SELECT MAX(_version) FROM `{TEST_DB_NAME}`.`{TEST_TABLE_NAME}`")
+    max_version_in_ch = versions_query.result_rows[0][0]
+    assert max_version_in_ch >= 200, f"Expected max _version to be at least 200, got {max_version_in_ch}"
+    
+
+    # Now test realtime replication to verify versions continue correctly
+    # Start binlog replication
+    binlog_replicator_runner = BinlogReplicatorRunner(cfg_file=cfg_file)
+    binlog_replicator_runner.run()
+
+    time.sleep(3.0)
+    
+    # Start DB replicator in realtime mode
+    realtime_db_replicator = DbReplicatorRunner(TEST_DB_NAME, cfg_file=cfg_file)
+    realtime_db_replicator.run()
+    
+    # Insert a new record with version 1001
+    mysql.execute(
+        f"INSERT INTO `{TEST_TABLE_NAME}` (name, age, version) VALUES ('UserRealtime', 99, 1001);", 
+        commit=True
+    )
+    
+    # Wait for the record to be replicated
+    assert_wait(lambda: len(ch.select(TEST_TABLE_NAME)) == 1001)
+    
+    # Verify the new record was replicated correctly
+    realtime_record = ch.select(TEST_TABLE_NAME, where="name='UserRealtime'")[0]
+    assert realtime_record['age'] == 99
+    assert realtime_record['version'] == 1001
+    
+    # Check that the _version column in CH is a reasonable value
+    # With parallel workers, the _version won't be > 1000 because each worker
+    # has its own independent version counter and they never intersect
+    versions_query = ch.query(f"SELECT _version FROM `{TEST_DB_NAME}`.`{TEST_TABLE_NAME}` WHERE name='UserRealtime'")
+    ch_version = versions_query.result_rows[0][0]
+
+
+    # With parallel workers (default is 4), each worker would process ~250 records
+    # So the version for the new record should be slightly higher than 250
+    # but definitely lower than 1000
+    assert ch_version > 0, f"ClickHouse _version should be > 0, but got {ch_version}"
+    
+    # We expect version to be roughly: (total_records / num_workers) + 1
+    # For 1000 records and 4 workers, expect around 251
+    expected_version_approx = 1000 // cfg.initial_replication_threads + 1
+    # Allow some flexibility in the exact expected value
+    assert abs(ch_version - expected_version_approx) < 50, (
+        f"ClickHouse _version should be close to {expected_version_approx}, but got {ch_version}"
+    )
+    
+    # Clean up
+    binlog_replicator_runner.stop()
+    realtime_db_replicator.stop()
+    db_replicator_runner.stop()
+
+
 def test_database_tables_filtering():
     cfg = config.Settings()
     cfg.load('tests_config_databases_tables.yaml')
@@ -693,8 +816,8 @@ def test_datetime_exception():
     name varchar(255),
     modified_date DateTime(3) NOT NULL,
     test_date date NOT NULL,
-    PRIMARY KEY (id)
-); 
+        PRIMARY KEY (id)
+    );
     ''')
 
     mysql.execute(