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;
Same query on slave03 and slave04:
select now() - pg_last_xact_replay_timestamp() AS replication_delay;
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
-----------------+---------------+----------
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.
I'm using PostgreSQL 9.2.14
Thanks!
Patrick.