I’ve been able to use the slow query log to spot poor performing queries. I have then used explain to identify the problem and improve upon the queries.
Today, the slow query log and explain do not agree. For example:
I see an entry like the following:
Query_time: 55 Lock_time: 24 Rows_sent: 0 Rows_examined: 489622
I take the query and run explain and it is perfectly well tuned, examining only a few 100 rows (according to explain) and even runs in a couple hundred ms when running the query stand alone.
Any ideas ??