TRUNCATE is usually a fast operation (much faster than DELETE FROM). But sometimes it just hangs; I've has several such uncheerful events with InnoDB (Plugin) tables which were extensively written to. The TRUNCATE hanged; nothing else would work; minutes pass.
TRUNCATE on tables with no FOREIGN KEYs should act fast: it translate to dropping the table and creating a new one (and it all depends on the MySQL version, see the manual).
What's faster than TRUNCATE, then? If you don't have triggers nor FOREIGN KEYs, a RENAME TABLE can come to the rescue. Instead of:
CREATE TABLE log_table_new LIKE log_table; RENAME TABLE log_table TO log_table_old, log_table_new TO log_table; DROP TABLE log_table_old;
I found this to work well for me. Do note that AUTO_INCREMENT values can be tricky here: the "new" table is created with an AUTO_INCREMENT value which is immediately taken in the "working" table. If you care about not using same AUTO_INCREMENT values, you can:
ALTER TABLE log_table_new AUTO_INCREMENT=some high enough value;
Just before renaming.
I do not have a good explanation as for why the RENAME TABLE succeeds to respond faster than TRUNCATE.