How do you fix a MySQL “Incorrect key file” error when you can't repair the table?

Question

I\'m trying to run a rather large query that is supposed to run nightly to populate a table. I\'m getting an error saying Incorrect key file for table \'/var/tmp/#sql

Answer 1

You must change the location of MySQL's temporary folder which is '/tmp' in most cases to a location with a bigger disk space. Change it in MySQL's config file.

Basically your server is running out of disk space where /tmp is located.