pg_stat_bgwriter

gistfile1.sql

SELECT
    (100 * checkpoints_req) /
        (checkpoints_timed + checkpoints_req) AS checkpoints_req_pct,
    pg_size_pretty(buffers_checkpoint * block_size /
         (checkpoints_timed + checkpoints_req)) AS avg_checkpoint_write,
    pg_size_pretty(block_size *
        (buffers_checkpoint + buffers_clean + buffers_backend)) AS total_written,
    100 * buffers_checkpoint /
        (buffers_checkpoint + buffers_clean + buffers_backend) AS checkpoint_write_pct,
    100 * buffers_backend /
        (buffers_checkpoint + buffers_clean + buffers_backend) AS backend_write_pct,
    *
FROM pg_stat_bgwriter,
(SELECT cast(current_setting('block_size') AS integer) AS block_size) bs;