If you ever wondered why a query that looks harmless is performing poorly despite having indexes in place, the answer could non-SARGable queries. First appeared on SQL SERVER – Catching Non-SARGable Queries in Action| SQL Authority with Pinal Dave
When trying to understand queries in the slow log, an interesting metric to look at is rows examined. Also, when trying to understand CPU spikes on a MySQL instance, the InnoDB Metric dml_reads and the global status Innodb_rows_read are interesting to check. In a similar way, when trying to gather information about which queries are loading the system, SUM_ROWS_EXAMINED from the| J-F Gagné's MySQL Blog