| SELECT pgperf.create_snapshot_pg_stat_bgwriter(0); |
| create_snapshot_pg_stat_bgwriter |
| ---------------------------------- |
| t |
| (1 row) |
| |
| SELECT count(*) = 1 |
| FROM pgperf.snapshot_pg_stat_bgwriter |
| WHERE sid = 0 |
| AND checkpoints_timed >= 0 |
| AND checkpoints_req >= 0 |
| AND checkpoint_write_time >= 0 |
| AND checkpoint_sync_time >= 0 |
| AND buffers_checkpoint >= 0 |
| AND buffers_clean >= 0 |
| AND maxwritten_clean >= 0 |
| AND buffers_backend >= 0 |
| AND buffers_backend_fsync >= 0 |
| AND buffers_alloc >= 0 |
| AND stats_reset IS NOT NULL; |
| ?column? |
| ---------- |
| t |
| (1 row) |
| |
| CREATE TABLE t1 AS |
| SELECT * FROM generate_series(1,1000); |
| SELECT 1000 |
| CHECKPOINT; |
| CHECKPOINT |
| SELECT pg_sleep(1); |
| pg_sleep |
| ---------- |
| |
| (1 row) |
| |
| SELECT pgperf.create_snapshot_pg_stat_bgwriter(1); |
| create_snapshot_pg_stat_bgwriter |
| ---------------------------------- |
| t |
| (1 row) |
| |
| SELECT b.sid - a.sid = 1, |
| b.checkpoints_timed - a.checkpoints_timed = 0, |
| b.checkpoints_req - a.checkpoints_req > 0, |
| b.checkpoint_write_time - a.checkpoint_write_time >= 0, |
| b.checkpoint_sync_time - a.checkpoint_sync_time > 0, |
| b.buffers_checkpoint - a.buffers_checkpoint > 0, |
| b.buffers_clean - a.buffers_clean = 0, |
| b.maxwritten_clean - a.maxwritten_clean = 0, |
| b.buffers_backend - a.buffers_backend > 0, |
| b.buffers_backend_fsync - a.buffers_backend_fsync = 0, |
| b.buffers_alloc - a.buffers_alloc > 0, |
| b.stats_reset - a.stats_reset = '0'::interval |
| FROM ( SELECT * FROM pgperf.snapshot_pg_stat_bgwriter WHERE sid = 0 ) AS a, |
| ( SELECT * FROM pgperf.snapshot_pg_stat_bgwriter WHERE sid = 1 ) AS b |
| ; |
| ?column? | ?column? | ?column? | ?column? | ?column? | ?column? | ?column? | ?column? | ?column? | ?column? | ?column? | ?column? |
| ----------+----------+----------+----------+----------+----------+----------+----------+----------+----------+----------+---------- |
| t | t | t | t | t | t | t | t | t | t | t | t |
| (1 row) |
| |
| CREATE TABLE t2 AS |
| SELECT * FROM generate_series(1,1000); |
| SELECT 1000 |
| CHECKPOINT; |
| CHECKPOINT |
| SELECT pgperf.create_snapshot_pg_stat_bgwriter(2); |
| create_snapshot_pg_stat_bgwriter |
| ---------------------------------- |
| t |
| (1 row) |
| |
| SELECT count(*) = 3 FROM pgperf.snapshot_pg_stat_bgwriter; |
| ?column? |
| ---------- |
| t |
| (1 row) |
| |
| SELECT pgperf.delete_snapshot_pg_stat_bgwriter(1); |
| delete_snapshot_pg_stat_bgwriter |
| ---------------------------------- |
| t |
| (1 row) |
| |
| SELECT count(*) = 0 FROM pgperf.snapshot_pg_stat_bgwriter WHERE sid = 1; |
| ?column? |
| ---------- |
| t |
| (1 row) |
| |
| SELECT count(*) = 2 FROM pgperf.snapshot_pg_stat_bgwriter; |
| ?column? |
| ---------- |
| t |
| (1 row) |
| |
| DROP TABLE t1,t2; |
| DROP TABLE |