A Guide to Logical Replication and CDC in PostgreSQL

PostgreSQL is an open-source relational database management system that has evolved over decades of careful stewardship. It is widely used for replicating data between servers, ensuring high availability and load balancing. In this blog, we discuss how to use logical replication in PostgreSQL to efficiently replicate data between instances and other data stores. Database replication involves copying and maintaining database objects in multiple locations. This can happen synchronously or asynchronously, at the byte, block, or logical level. Replication is crucial for high availability, load balancing, and data activation. PostgreSQL's replication mechanisms include the Write-Ahead Log (WAL), which records every change in the database, and replication slots that track the progress of replication across subscribers. There are two types of replication in PostgreSQL: physical and logical. Physical replication is at the byte level, while logical replication is at the transaction level. Logical replication is more flexible and can be used to sync data between Postgres servers or to OLAP environments for further processing and analysis using tools like Airbyte. To set up master-replica logical replication in PostgreSQL, configure your primary database by enabling logical replication, creating a user role with replication privileges, and allowing the replication role to connect from the replicas' IP addresses. Then, create a publication on the primary and a subscription on each standby server. To replicate data between PostgreSQL and external data stores using Airbyte, first create a replication slot on your Postgres database and configure publication and replication identities for each table you want to replicate. Next, set up your PostgreSQL source connector in the Airbyte UI and a destination connector (such as BigQuery, Snowflake, or Redshift). In conclusion, PostgreSQL's logical replication capabilities make it an excellent choice for various use cases, including data replication between servers and OLAP environments. By leveraging tools like Airbyte, users can efficiently manage their CDC replication setups.