Poor pt-heartbeat 2.1: it was perfectly fine through Percona Toolkit 2.1.7, but it’s had a rough life since. Its troubles are finally over as of Percona Toolkit 2.1.10. At a conference recently, a user joked to me that “Percona Toolkit is awesome, but you really broke pt-heartbeat.” It’s true, and if you haven’t heard or experienced the story, here it is for the record.
Since the dawn of time, pt-heartbeat had computed slave lag like:
t1=time (Perl) --> replicate --> t2=time (Perl); lag = t2 - t1
Surprisingly, that worked for many years despite what should have been an obvious problem: different time zones: t1 could be in PST …[Read more]