During an upgrade to Percona XtraDB Cluster 5.6, I faced an issue that I wanted to share. In this environment, we set up three Percona XtraDB Cluster nodes (mostly configured as default), copied from a production server. We configured one of the members of the cluster as the slave of the production server.
During the testing process, we found that a full table scan query was taking four times less in the nodes where replication was not configured. After reviewing mostly everything related to the query, we decided to use perf.
perf record -a -g -F99 -p $(pidof mysqld) -- sleep 60
And the query in another terminal a couple of times. …[Read more]