I am frequently seeing invalid values in HA–>MySQL replication summary.
You can see the lag value suddenly increasing from 0 to a very big value 14377389, I am sure this is not the real lag value for this instance. It’s like some kind of numerical value overflow, could someone can help with this? Thanks
PMM I used is the latest version 2.26.0.
Hi @Luke03011 , thank you for posting to the Percona forums
These artifacts are safe to ignore, and are due to the way Seconds_Behind_Source variable is generated. From the docs:
It is also possible that transient values for
Seconds_Behind_Source may not reflect the situation accurately. When the replication SQL (applier) thread has caught up on I/O,
Seconds_Behind_Source displays 0; but when the replication I/O (receiver) thread is still queuing up a new event,
Seconds_Behind_Source may show a large value until the replication applier thread finishes executing the new event. This is especially likely when the events have old timestamps; in such cases, if you execute
SHOW REPLICA STATUS several times in a relatively short period, you may see this value change back and forth repeatedly between 0 and a relatively large value.
An alternative method to tracking replication delay is to use the pt-heartbeat
@Michael_Coburn Thanks for your quick response.