Offset
An offset identifies the location information for data synchronization between the replication source and the replication destination. It records the updates of the source database and identifies the location of the destination database to which DTS synchronizes data. Offsets ensure the consistency of data between the replication source and destination and can be used for data recovery and backup.
HA switchover
In case of a system failure or other unavailability, the workload can be automatically or manually switched from one node to another to ensure service continuity and availability. This process is referred to as a high availability (HA) switchover.
VPC
A virtual private cloud (VPC) is a virtual network. VPC-based data migration refers to the real-time migration between a source database and a destination database that are located within the same VPC or across VPCs. You do not need to build other networks.
Migration Instance
A migration instance refers to an instance that performs migration tasks. It exists in the entire lifecycle of a migration task. DTS uses the migration instance to connect to the source database, read source data, and replicate the data to the destination database.
Sync Instance
A synchronization instance refers to an instance that performs synchronization tasks. It exists in the entire lifecycle of a synchronization task. DTS uses the synchronization instance to connect to the source database, read source data, and synchronize the data to the destination database.
Precheck
A precheck is performed before a migration task starts. It checks factors and conditions that may affect the execution of the migration task. If any check item fails, fix the issue as prompted. After all detected issues are fixed, re-perform the precheck. You can start a task only when all check items are passed.
Struct Migration
In the struct migration stage, DTS migrates the struct definitions of selected objects from the source database to the destination database, such as tables, views, triggers, and stored procedures. For struct migration between heterogeneous databases, DTS converts the struct definition of the source database to that supported by the destination database. For example, it converts the NUMBER data type of Oracle databases to the DECIMAL data type of MySQL databases.
Full Data Migration
In the full data migration stage, DTS migrates all existing data from the source database to the destination database. If you only select struct migration and full data migration for a data migration task, DTS does not migrate data changes in the source database to the destination database. Therefore, do not write new data to the source database during migration to ensure data consistency.
Incremental Data Migration
In the incremental data migration stage, DTS synchronizes the incremental data generated in the source database to the destination database in real time. This feature migrates the data changes that have occurred in the full data migration stage without service downtime.