This topic describes the terms that are used in the Data Transmission Service (DTS) documentation.
Term | Synonym | Description |
Term | Synonym | Description |
Regular instance | Single-zone instance | A DTS instance in single-zone deployment mode, where the databases are deployed on the servers that reside in the same zone. If a server in the zone fails, the DTS instance switches to another server that runs as expected in the zone. This feature ensures the availability of the DTS instance. If a zone in which a DTS instance resides becomes unavailable, an exception occurs. All DTS instances are regular instances in single-zone deployment mode at presrnt. |
Self-managed database | Self-managed DB | A DTS instance where the Alibaba Cloud Instance is not selected in the Access Method. The self-managed databases include third-party cloud databases, on-premises databases, and databases deployed on an Elastic Compute Service (ECS) instance. |
Schema task | Structure task | The task corresponding to the Schema Synchronization or Schema Migration that tuns. |
Full data task | Full task | The task corresponding to the Full Data Synchronization or Full Data Migration that runs. |
Incremental task | Incremental task | The task corresponding to the Incremental Data Synchronization or Incremental Data Migration that runs. By default, a synchronization instance includes Incremental Data Synchronization. |
Schema synchronization | Schema synchronization | A DTS instance that reads the schemas such as tables, views, triggers, and stored procedures of the objects to be synchronized or migrated from the source database and writes the schemas to the destination database. When you synchronize or migrate the schema between heterogeneous databases, DTS converts the schema in the source database to a schema that is supported by the destination database before writing to the destination database. For example, DTS converts the NUMBER data type in an Oracle database to the DECIMAL data type before writing data to a MySQL database. |
Schema migration | Structure migration | |
Full data synchronization | Full synchronization | A DTS instance that reads the historical data of the objects to be synchronized or migrated from the source database and writes all the data to the destination database. In this case, the historical data refers to the data before a DTS instance starts to run. |
Full data migration | Full migration | |
Incremental data synchronization | Incremental synchronization | A DTS instance that synchronizes or migrates data changes that occur when a DTS task is running by retrieving the incremental change statements of the objects to be synchronized or migrated from the source database, such as the incremental change statements from the Binlog of a MySQL database, converting the statements according to the type of the destination database, and executing the statements converted in the destination database. This achieves real-time synchronization or migration of incremental data to the destination database. The DTS instance is commonly used to achieve data synchronization or migration without service disruption.
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Incremental data migration | Incremental migration | |
Precheck | Precheck | The operation that the system performs before a DTS instance starts. For example, the following items are checked in advance: the connectivity between the source and destination databases, database account permissions, binary log settings, and database versions. For more information, see Source database connectivity. If a task fails to pass the precheck, you can view the details. After you troubleshoot the issues based on the causes, run the precheck again. |
Initial synchronization | Initial synchronization | The initial synchronization phase during which DTS collects incremental data and then synchronizes the schemas and historical data of objects from the source database to the destination database. This happens before DTS starts to synchronize incremental data. Initial synchronization includes incremental data collection, initial schema synchronization, and initial full data synchronization.
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Performance | Synchronization performance | A measurement based on the number of incremental data records that are synchronized to the destination database per second. Unit: records per second (RPS). For more information, see Instance classes of data synchronization instances, Instance classes of data migration instances, and Instance classes of serverless instances. |
Migration performance | ||
Latency | Synchronization latency | A measurement based on the difference between the timestamp of the latest data record synchronized or migrated to the destination database and the current timestamp of the source database. If the synchronization latency is zero, the destination database is in sync with the source database. The latency of a DTS instance might not always display as 0. If no data is written to the source database and the latency of a DTS instance is 0, the latency may vary within 2 seconds. |
Migration latency | ||
Data update | Data update | The operations that are performed to modify data without modifying schemas, such as the INSERT, DELETE, and UPDATE operations. |
Schema update | Schema update | The operations that are performed to modify schema syntax, such as the CREATE TABLE, ALTER TABLE, and DROP VIEW operations. |
Timestamp range | Timestamp range | The timestamp range of the incremental data that is stored in a change tracking task. By default, a change tracking task retains the data that is generated in the last 24 hours. DTS regularly deletes expired incremental data and updates the timestamp range of change tracking tasks. The timestamp of incremental data is generated when the data is updated in the source database and written to the transaction log. |
Consumption checkpoint | Consumer offset | The timestamp of the latest incremental data record that is consumed by a client. Each time the client consumes a data record, it returns a confirmation message to DTS. DTS updates and saves the consumption checkpoint. If the client stops responding, DTS automatically resumes data from the last consumption checkpoint and pushes the data to another consumer. |
Data verification task | Verification task | The task includes full data verification tasks, incremental data verification tasks, and schema verification tasks. |
Task type | Task type |
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