In this blog post, I investigate a case of spiking InnoDB Rows inserted in the absence of a write query, and find internal temporary tables to be the culprit.
Recently I was investigating an interesting case for a customer. We could see the regular spikes on a graph depicting “InnoDB rows inserted” metric (jumping from 1K/sec to 6K/sec), however we were not able to correlate those spikes with other activity. The
graph (picture from PMM demo) looked similar to this (but on a much larger scale):
Other graphs (Com_*, Handler_*) did not show any spikes like that. I’ve examined the logs (we were not able to enable general log or change the threshold of the slow log), performance_schema, triggers, stored procedures, prepared statements and even reviewed the binary logs. However, I was not able to find any single …[Read more]