This topic describes the terms that are used in the DTS documentation.
|precheck||The system performs a precheck before starting a data migration task, data synchronization
task, or change tracking task. The following items are checked: the connectivity between
the DTS server and the source and destination databases, database account permissions,
whether binary logging is enabled, and database version numbers.
Note If the precheck fails, click the icon next to each failed item to view the related details. Fix the issues as instructed and run the precheck again.
|schema migration||DTS migrates the schemas of the objects that you have selected from the source instance to the destination instance. Tables, views, triggers, and stored procedures can be migrated. For schema migration between heterogeneous databases, DTS converts the schema syntax based on the syntax of the source and destination databases. For example, it converts the NUMBER data type of Oracle databases to the DECIMAL data type of MySQL databases.|
|full data migration||
DTS migrates historical inventory data of the objects that you have selected from the source database to the destination database.
If you select only schema migration and full data migration, new data generated in the source database will not be migrated to the destination database. To ensure data consistency, we recommend that you do not write new data into the source database during full data migration.
Note To migrate data with minimized downtime, you must select schema migration, full data migration, and incremental data migration.
|incremental data migration||DTS synchronizes the incremental data generated in the source database to the destination
database in real time.
Note During incremental data migration, data between the source and destination databases is synchronized in real time. The migration task does not automatically end. You need to manually end the migration task.
DTS synchronizes the schemas and historical inventory data of the objects that you have selected to the destination database before synchronizing incremental data. Initial synchronization includes initial schema synchronization and initial full data synchronization.
|synchronization performance||The synchronization performance is the number of records that are synchronized to the destination database per second. The unit is records per second (RPS). For more information, see Specifications of data synchronization channels.|
The synchronization latency is the difference between the timestamp of the latest data synchronized to the destination database and the current timestamp of the source database. Synchronization latency reflects the time difference between the source and destination databases for the latest data. If the synchronization latency is zero, data in the source database is consistent with that in the destination database.
|data update||Data updates are operations that only modify data without modifying the schema, such as INSERT, DELETE, and UPDATE operations.|
|schema update||Schema updates are operations that modify the schema syntax, such as CREATE TABLE, ALTER TABLE, and DROP VIEW operations.|
The timestamp range is the range of timestamps for the incremental data that is stored in the change tracking channel. By default, the change tracking channel retains the data that is generated in the most recent 24 hours. DTS regularly cleans expired incremental data and updates the timestamp range of the change tracking channel.
Note The timestamp of the incremental data is the timestamp when the incremental data is updated in the source database and written into the transaction log.
The consumption checkpoint is the timestamp of the latest incremental data that is consumed by using the downstream SDK client.
Each time the SDK client consumes a data record, it returns a confirmation message to DTS. DTS updates and saves the consumption checkpoint. If the SDK client restarts due to exceptions, DTS automatically pushes subscribed data from the last consumption checkpoint.