mysqldump out of memory error 5

Tonight I was trying to mysqldump some large tables, but kept getting "mysqldump out of memory error 5". I knew I had dumped tables larger than the ones I was dumping, so I wasn't sure what was going on. After poking around with mySQL settings in my.cnf to no avail, I decided to try optimize table. That seemed to fix the problem. The reason it came to mind is because I had purged about 100,000 rows of the problematic table earlier in the day and thought maybe it needed cleanup

bottom line:
mysqldump giving "out of memory" error, try:
optimze table myTable