This topic provides answers to some commonly asked questions about data synchronization to Hologres.

What do I do if the connectivity test fails for the PolarDB data source?

  • Problem description: The connectivity test fails when a PolarDB data source is added.
  • Solution: Set Data source type to Connection string mode, 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 the connectivity test fails for the Oracle data source?

What do I do if the connectivity test fails for the MySQL data source?

The system displays the following error message for a real-time data 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.
  • Possible cause: The binary logging feature is disabled for the PolarDB source data source.
  • Solution: Enable the binary logging feature for the PolarDB data source. For more information, see Configure a data source (PolarDB). Change one or more data records and change the start time to run the real-time data synchronization node to the current time.

The system displays the following error message for a real-time data 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.
  • Possible cause: The account used to synchronize data is not authorized to access the PolarDB source data source, or the PolarDB database connected is not deployed on the primary node.
  • Solution: Refer to the operations in Configure a data source (PolarDB) to authorize the account to access the PolarDB data source. Alternatively, check whether the PolarDB database connected is deployed on the primary node. During the running of a real-time data synchronization node, the system cannot capture data from the read-only nodes of the PolarDB cluster.

The system displays the following error message for a real-time data 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.
  • Possible cause: The loose_polar_log_bin parameter is not specified for the PolarDB source data source.
  • Solution: Specify the loose_polar_log_bin parameter. For more information, see Configure a data source (PolarDB).