Muhammad Ali keeps an eye on things:
In PostgreSQL, a checkpoint is an operation during which the database flushes/syncs all pending modifications(dirty buffers) inside memory to the actual data files on the disk.
This is important for two primary reasons. Firstly, it guarantees that all committed transactions are permanently stored, thereby safeguarding against data loss in the event of a system failure. Secondly, it works closely with the database recovery mechanism. If a crash occurs, PostgreSQL begins processing WAL logs starting from the last successful checkpoint(It gets this information from the pg_control file located in the PG data directory) during recovery. Additionally, this process allows for the fine-tuning of performance through a variety of parameters, adaptable to specific workload requirements which are discussed below.
Read on to learn more about how checkpoints work in Postgres, how the background writer works, and things to keep in mind.