Semab Tariq continues a series on internals by covering write-ahead logging:
Write-Ahead Logging (WAL) is a critical feature in PostgreSQL that ensures data integrity and durability. It records changes to the database before they are applied, allowing PostgreSQL to recover data and restore the database to its most recent state in case of a crash or failure.
Before the introduction of Write-Ahead Logging (WAL) in PostgreSQL, PostgreSQL relied on a simpler mechanism for ensuring data integrity, which was less robust and did not support advanced features like point-in-time recovery and replication.
Read on for a bit of history, how write-ahead logging has changed over the years, and the basics of how it works. Write-ahead logging is a common feature in major relational databases and serves a critical purpose for database consistency. There are also some sneaky performance gains you can get out of it.