On 06/12/2016 04:20, Patrick B wrote:
Hi guys,I've got some database servers in USA (own data center) and also @ AWS Japan. *USA:* master01 slave01 (Streaming Replication from master01 + wal_files) slave02 (Streaming Replication from master01 + wal_files) *Japan: (Cascading replication)* slave03 (Streaming Replication from slave02 + wal_files) slave04 (Streaming Replication from slave02) *Running this query on slave02:* select now() - pg_last_xact_replay_timestamp() AS replication_delay; replication_delay ------------------- 00:00:00.802012 (1 row) *Same query on slave03 and slave04:* select now() - pg_last_xact_replay_timestamp() AS replication_delay; replication_delay ------------------- 00:56:53.639516 (1 row) *slave02:* SELECT client_hostname , client_addr , pg_xlog_location_diff(pg_stat_replication.sent_location, pg_stat_replication.replay_location) AS byte_lag FROM pg_stat_replication; client_hostname | client_addr | byte_lag -----------------+---------------+---------- | slave03 | 2097400 | slave04 | 3803888 (2 rows) Why is that delay that big? Is it because networking issue? I tried to find out what the cause is, but couldn't find anything. SCP and FTP (big files) between those servers are really fast, +1.0MB/s.
Are you sure the upstream does not produce WAL activity at a higher rate than 0.5MB/s ?
I'm using PostgreSQL 9.2.14 Thanks! Patrick.
-- Achilleas Mantzios IT DEV Lead IT DEPT Dynacom Tankers Mgmt
