How can I count the numbers of rows that a MySQL query returned?

Question

How can I count the number of rows that a MySQL query returned?

Answer 1

This is not a direct answer to the question, but in practice I often want to have an estimate of the number of rows that will be in the result set. For most type of queries, MySQL's "EXPLAIN" delivers that.

I for example use that to refuse to run a client query if the explain looks bad enough.

Then also daily run "ANALYZE LOCAL TABLE" (outside of replication, to prevent cluster locks) on your tables, on each involved MySQL server.