You might have encountered situations where you had to kill some specific select queries that were running for long periods and choking the database. This post will go into more detail with an example of report query offloading.
Report query (select) offloading to a slave server is a common practice to reduce the workload of the master DB server. The long running selects will be executed in the slave for report generation. I have observed in many cases where the slave used to get delayed or the slave DB encounters a slowdown due to some heavy long-running orphaned selects from some wrong reports.
There are two …[Read more...]