Capture Data Change(CDC)
MySQL provides binary log files to record data changes. A binary log file can be regarded as a message queue that stores detailed incremental data changes in chronological order. Downstream systems or tools consume the changes in the queue to synchronize data from MySQL in real time. This mechanism is also referred to as change data capture (CDC).
PolarDB-X is a distributed database service that is compatible with the MySQL ecosystem. A PolarDB-X instance uses the CDC component to provide change logs that are compatible with the binary log format of MySQL. The distributed features of PolarDB-X, such as instance scaling, distributed transactions, and global indexes, are not reflected in the change logs. This way, you can use a PolarDB-X instance in the same manner that you use a standalone MySQL database.
In addition to using external systems as data storage, the CDC component of PolarDB-X supports business deployment in the active geo-redundancy architecture. For example, users are granted write permissions on different data centers based on the areas to which the users belong. In this case, users can only write data in the specified data centers. For read operations, each user can read data from the replica nearest to the geographical area in which the user resides. PolarDB-X uses the CDC component to synchronize data to the replicas when the data is written to a data center.