pg_stat_bgwriter

The pg_stat_bgwriter view provides cumulative statistics about the background writer process, which is responsible for writing dirty buffers to disk in the background. This view helps monitor the efficiency of the background writer and overall buffer management. It includes metrics such as the number of buffers written during checkpoints, buffers cleaned by the background writer, and buffers written directly by backend processes. These statistics are useful for tuning database performance and understanding write activity patterns.

column	type	references	description
checkpoints_timed	bigint		Number of scheduled checkpoints that have been performed.
checkpoints_req	bigint		Number of requested checkpoints that have been performed.
checkpoint_write_time	double precision		Total amount of time that has been spent in the portion of checkpoint processing where files are written to disk, in milliseconds.
checkpoint_sync_time	double precision		Total amount of time that has been spent in the portion of checkpoint processing where files are synchronized to disk, in milliseconds.
buffers_checkpoint	bigint		Number of buffers written during checkpoints.
buffers_clean	bigint		Number of buffers written by the background writer.
maxwritten_clean	bigint		Number of times the background writer stopped a cleaning scan because it had written too many buffers.
buffers_backend	bigint		Number of buffers written directly by a backend.
buffers_backend_fsync	bigint		Number of times the background writer stopped a cleaning scan because it had written too many buffers.
buffers_alloc	bigint		Number of buffers allocated.
stats_reset	timestamp with time zone		Time at which these statistics were last reset.