Describes the Write-Ahead-Log Internals of PostgreSQL system. Improvements in WAL system that can be done to improve the performance. PostgreSQL uses WAL files to perform Crash recovery, Point In Time Recovery and Streaming Replication. This article will cover details of WAL system in PostgreSQL like what kind os WAL record gets generated on DML operations. WAL file name details and the contents it contains. The details of Async Commit and how it protects Partial Page writes using WAL system are covered. Finally some Advantages/Disadvantages and improvements w.r.t other RDBMS that can be done in PostgreSQL WAL system to improve its performance.