Earlier in the year, I was working on an issue where one of my clients had reported a massive influx in connection on their hosts after enabling Percona Monitoring and Management (PMM). This was something I had not seen before and after researching for a couple of days I discovered that if you monitor a MySQL instance with PMM configured to collect table statistics, and if the tables that it’s gathering statistics from are Federated, it will generate a connection on the remote host for the Federated tables, one for each Federated table in the instance. Let’s go over the details and provide some examples so we can understand this a bit better.
First, I’ll offer a reminder that a Federated table is simply a table that you can put in your MySQL instance that is empty locally and uses a network connection to get the data from …
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