PG_STAT_BGWRITER

PG_STAT_BGWRITER displays statistics about the activity of the background writer process. For details about the columns, see Table 1.

**Table 1** PG_STAT_BGWRITER columns
Name	Type	Description
checkpoints_timed	bigint	Number of scheduled checkpoints that have been performed.
checkpoints_req	bigint	Number of checkpoints that have been performed actively.
checkpoint_write_time	double precision	Total time spent in the checkpoint processing portion when writing files to disk, in milliseconds.
checkpoint_sync_time	double precision	Total time spent in the checkpoint processing portion when synchronizing files to disk, in milliseconds.
buffers_checkpoint	bigint	Number of buffers written by checkpoints.
buffers_clean	bigint	Number of buffers written by the background writer process.
maxwritten_clean	bigint	Number of times that cleanup scanning stops because the background writer process writes too many buffers.
buffers_backend	bigint	Number of buffers written directly by the backend.
buffers_backend_fsync	bigint	Number of times that the backend calls fsync (usually, even if the backend executes these write actions, the background writer process processes them again).
buffers_alloc	bigint	Number of buffers allocated.
stats_reset	timestamp with time zone	Time at which these statistics were last reset.