Logical Decoding

The data replication capabilities supported by GaussDB are as follows:

Data is periodically synchronized to heterogeneous databases (such as database A) using a data migration tool. Real-time data replication is not supported. Therefore, the requirements for real-time data synchronization to heterogeneous databases are not satisfied.

GaussDB provides the logical decoding function to generate logical logs by decoding Xlogs. A target database parses logical logs to replicate data in real time. For details, see Figure 1. Logical replication reduces the restrictions on target databases, allowing for data synchronization between heterogeneous databases and homogeneous databases with different forms. It allows data to be read and written during data synchronization on a target database, reducing the data synchronization latency.

Logical replication consists of logical decoding and data replication. Logical decoding outputs logical logs by transaction. The database service or middleware parses the logical logs to implement data replication. Currently, GaussDB supports only logical decoding. Therefore, this section involves only logical decoding.

• Overview
  
• Logical Decoding Options
  
• Logical Decoding by SQL Functions
  
• Replicating Data Using the Logical Replication Tool