Identifying checkpoint overhead
In this recipe, we will be discussing the checkpoint process, which may cause more I/O usage while flushing the dirty buffers into the disk.
Getting ready
In PostgreSQL, the checkpoint is an activity that flushes all the dirty buffers from the shared buffers into the persistent storage, which is followed by updating the consistent transaction log sequence number in the data, WAL files. That means this checkpoint guarantees that all the information up to this checkpoint number is stored in a persistent disk storage. PostgreSQL internally issues the checkpoint as per the checkpoint_timeout and max_wal_size settings, which keep the data in a consistent storage as configured. In case the configured shared_buffers are huge in size, then the probability of holding dirty buffers will also be greater in size, which leads to more I/O usage for the next checkpoint process. It is also not recommended to tune the checkpoint_timeout and max_wal_size settings to be aggressive...
