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* postgresql replication replay lag
@ 2021-12-27 16:22 Kenny Bachman <kenny.bachman17@gmail.com>
2021-12-29 04:53 ` Re: postgresql replication replay lag Laurenz Albe <laurenz.albe@cybertec.at>
0 siblings, 1 reply; 2+ messages in thread
From: Kenny Bachman @ 2021-12-27 16:22 UTC (permalink / raw)
To: pgsql-admin@lists.postgresql.org
Hello PG Team,
I have a 3-nodes Patroni cluster with PG 12.9. There is a replay lag on the
third node. I don't understand why there is lag. The replication view
output is below :
Extra info: There is no long-running query on the third node.
Where can I check to detect what's causing this?
Thank you,
Best,
Kenny
-[ RECORD 1 ]----+------------------------------
pid | 1442401
usesysid | 15302
usename | replicator
application_name | henb
client_addr | 10.109.15.94
client_hostname | henb.acc
client_port | 43286
backend_start | 2021-11-13 15:16:43.462115
backend_xmin |
state | streaming
sent_lsn | 8E66/4FC9F618
write_lsn | 8E66/4FC9F618
flush_lsn | 8E66/4FC9F618
replay_lsn | 8E66/4F58F000
write_lag | 00:00:00.000653
flush_lag | 00:00:00.00126
replay_lag | 00:00:05.463059
sync_priority | 0
sync_state | async
reply_time | 2021-12-27 17:02:56.750262+03
-[ RECORD 2 ]----+------------------------------
pid | 1390172
usesysid | 15302
usename | replicator
application_name | henc
client_addr | 10.109.15.95
client_hostname | henc.acc
client_port | 47982
backend_start | 2021-11-13 15:19:42.065277
backend_xmin |
state | streaming
sent_lsn | 8E66/4FC9F618
write_lsn | 8E66/4FC9F618
flush_lsn | 8E66/4FC9F618
replay_lsn | 8E63/6E340B20
write_lag | 00:00:00.010311
flush_lag | 00:00:00.01101
*replay_lag | 02:00:15.147839*
sync_priority | 0
sync_state | async
reply_time | 2021-12-27 17:02:56.7555
^ permalink raw reply [nested|flat] 2+ messages in thread
* Re: postgresql replication replay lag
2021-12-27 16:22 postgresql replication replay lag Kenny Bachman <kenny.bachman17@gmail.com>
@ 2021-12-29 04:53 ` Laurenz Albe <laurenz.albe@cybertec.at>
0 siblings, 0 replies; 2+ messages in thread
From: Laurenz Albe @ 2021-12-29 04:53 UTC (permalink / raw)
To: Kenny Bachman <kenny.bachman17@gmail.com>; pgsql-admin@lists.postgresql.org
On Mon, 2021-12-27 at 19:22 +0300, Kenny Bachman wrote:
> I have a 3-nodes Patroni cluster with PG 12.9. There is a replay lag on the third node.
> I don't understand why there is lag. The replication view output is below :
>
> Extra info: There is no long-running query on the third node.
>
> Where can I check to detect what's causing this?
On the lagging node, examine
SELECT * FROM pg_stat_activity;
That should show you what causes the lag.
Yours,
Laurenz Albe
--
Cybertec | https://www.cybertec-postgresql.com
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