How to Migrate PostgreSQL to Azure with Minimal Downtime Using WAL Replication

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Migrating a PostgreSQL database to Azure and maintaining high availability both rely on the same core mechanism: PostgreSQL's write-ahead log (WAL), which records every database change and streams it to replicas, backups, or migration targets. Azure Database for PostgreSQL supports three migration methods — pg_dump/pg_restore, Azure Database Migration Service, and logical replication — each offering different trade-offs between downtime and complexity. Logical replication, which copies row-level changes between servers, enables near-zero-downtime migrations by keeping source and target in sync until a final cutover. Key configuration concepts include zone-redundant high availability, read replicas, and the distinction between RTO (recovery time) and RPO (acceptable data loss), which together shape how a database is both migrated and kept resilient. The guide also covers identity and network access hardening, slow query tuning, and why physical versus logical replication determines what migration paths are available across PostgreSQL versions.

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