Physical vs Logical Backups in PostgreSQL

Summary

PostgreSQL backups fall into two distinct categories: logical backups, which convert data into SQL command files, and physical backups, which copy the underlying file system storage. Logical backups generated with pg_dump or pg_dumpall allow single-database targeting and provide the only practical route for migrating across major Postgres versions with differing internal storage formats. Conversely, physical backups suit larger databases where long-running logical exports can degrade concurrent query performance and risk failure. Physical backups also integrate with Write Ahead Log files through tools like WAL-G to support Point in Time Recovery and minimize Recovery Point Objectives. Selecting between these two strategies depends on whether administrative simplicity, version portability, cluster size, or precise disaster recovery takes precedence.

Context

Database administrators need appropriate backup strategies for PostgreSQL databases depending on database size, migration requirements, and recovery point objectives.

Approach / What changed

PostgreSQL supports logical backups via SQL export utilities like pg_dump and pg_dumpall, as well as physical backups created by copying underlying data files and pairing them with Write Ahead Log files.

Takeaways

• Logical backups generated via pg_dump or pg_dumpall export SQL commands, making them essential for migrating across major PostgreSQL versions where internal storage formats differ.
• Running logical backups on databases larger than a few gigabytes risks degraded query performance, long execution times, and errors that can render the backup unusable.
• Physical backups combined with Write Ahead Log files enable Point in Time Recovery, which minimizes Recovery Point Objectives during disaster recovery.

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