Slow query log should show what kind of temp.tables were used.

With log_slow_verbosity=Query_plan (http://kb.askmonty.org/en/slow-query-log-extended-statistics),
slow query log includes these fields:

• "Tmp_table"
• "Tmp_table_on_disk"

it is a common "conventional wisdom" that use of temp.table = bad query plan.

New optimizations in 5.3 create temporary tables, so it will become harder to see which tables does the slow query log refers to.

The suggested solution is to extend slow query log information to show what kinds of temptables were used.

Note: Percona Server 5.5 shows total temp. table sizes in the slow query log