The topic provides answers to some frequently asked questions about failures for real-time synchronization to AnalyticDB for MySQL V3.0.

What do I do if a PolarDB data source cannot be connected?

  • Problem description: The connectivity test fails when I add a PolarDB data source.
  • Solution: Set Data source type to Connection string mode and check the whitelist configuration of the PolarDB cluster and the virtual private cloud (VPC) configuration of your exclusive resource group.

What do I do if a MySQL data source cannot be connected?

  • Problem description: The connectivity test fails when I add a MySQL data source.
  • Solution: Set Data source type to Connection string mode and check the whitelist configuration of the PolarDB cluster and the virtual private cloud (VPC) configuration of your exclusive resource group.

The system displays the following error message for a real-time synchronization node: "com.alibaba.otter.canal.parse.exception.PositionNotFoundException: can't find start position for XXX." What do I do?

  • Problem description: The real-time synchronization node fails to run, and the system displays the error message "com.alibaba.otter.canal.parse.exception.PositionNotFoundException: can't find start position for XXX."
  • Cause: The binary logging feature is disabled for the PolarDB data source.
  • Solution: Enable the binary logging feature for the PolarDB data source. For more information, see Configure a data source (PolarDB). In addition, you must change one or more data records and change the start time for running the real-time sync node to the current time.

The system displays the following error message for a real-time synchronization node: "com.alibaba.otter.canal.parse.exception.CanalParseException: command : 'show master status' has an error! pls check. you need (at least one of) the SUPER,REPLICATION CLIENT privilege(s) for this operation." What do I do?

  • Problem description: The real-time synchronization node fails to run, and the system displays the error message "com.alibaba.otter.canal.parse.exception.CanalParseException: command : 'show master status' has an error! pls check. you need (at least one of) the SUPER,REPLICATION CLIENT privilege(s) for this operation."
  • Cause: The account used to synchronize data is not authorized to access the PolarDB data source, or the PolarDB database connected is not deployed on the PolarDB Writer node.
  • Solution: Authorize the account to access the PolarDB data source. For more information, see Configure a data source (PolarDB). You can also check whether the PolarDB database connected is deployed on the PolarDB Writer node. When a real-time sync node is run, the system cannot capture data from the PolarDB Reader nodes of the PolarDB cluster.

The system displays the following error message for a real-time synchronization node: "com.alibaba.datax.plugin.reader.mysqlbinlogreader.MysqlBinlogReaderException: The mysql server does not enable the binlog write function. Please enable the mysql binlog write function first." What do I do?

  • Problem description: The real-time synchronization node fails to run, and the system displays the error message "com.alibaba.datax.plugin.reader.mysqlbinlogreader.MysqlBinlogReaderException: The mysql server does not enable the binlog write function. Please enable the mysql binlog write function first."
  • Cause: The loose_polar_log_bin parameter is not specified for the PolarDB data source.
  • Solution: Specify the loose_polar_log_bin parameter. For more information, see Configure a data source (PolarDB).

The system displays the following error message for a real-time synchronization node: MongoDBReader$Task - operation exceeded time limitcom.mongodb.MongoExecutionTimeoutException: operation exceeded time limit. What do I do?

  • Problem description: When the real-time synchronization node is run, an error occurs and the system displays the following error message: MongoDBReader$Task - operation exceeded time limitcom.mongodb.MongoExecutionTimeoutException: operation exceeded time limit.
  • Cause: The amount of data that you want to synchronize is excessively large.
  • Solutions:
    • Increase the number of parallel threads for the node.
    • Reduce the value of the BatcSsize parameter.
    • Add the cursorTimeoutInMs parameter to the configurations of the Reader plug-in and specify a large value for this parameter, such as 3600000s.