subscribers

Many organizations using PostgreSQL face challenges in replicating data across different logical databases while controlling shared information. PostgreSQL 15 introduces native logical replication with column-level and row-level filtering within publications, allowing precise control over data transfer between PostgreSQL databases. Logical replication operates on a publish-subscribe model, where the source database logs changes to the Write-Ahead Log (WAL) and applies publication filters to transmit only the relevant data to the target database. Two filtering modes are available: column-level filtering allows users to specify which columns to replicate, while row-level filtering uses WHERE clauses to determine which rows to include. Both filtering modes can be combined in a single publication. The SQL syntax for creating publications and subscriptions is consistent across various PostgreSQL environments, with specific configurations required for enabling logical replication. Use cases for logical replication include multi-tenant SaaS data isolation, regional data distribution for ecommerce, PCI DSS compliance in financial services, development and testing environments, and retail inventory management. Prerequisites for implementing logical replication include using PostgreSQL 15 or later, ensuring network connectivity, having a user with replication privileges, enabling logical replication on the source instance, and monitoring WAL retention. Logical replication has limitations, such as the need for a replica identity for UPDATE and DELETE operations, the non-replication of DDL changes and sequences, and potential performance overhead during initial synchronization and ongoing replication. After testing, it is advisable to clean up by removing replication resources to prevent unnecessary costs.