- June 29, 2007 1:36 PM
tmp_table_size
The maximum size of in-memory temporary tables. (The
actual limit is determined as the smaller of
max_heap_table_size and
tmp_table_size.) If an in-memory
temporary table exceeds the limit, MySQL automatically
converts it to an on-disk MyISAM table.
Increase the value of tmp_table_size
(and max_heap_table_size if necessary)
if you do many advanced GROUP BY
queries and you have lots of memory.
http://dev.mysql.com/doc/refman/5.0/en/server-system-variables.html