Take the tour ×  Can any configuration mistake lead to creating
too many temp tables by mysql..mysql tuner shows  Current
max_heap_table_size = 200 M Current tmp_table_size = 200 M Of
17158 temp tables, 30% were created on disk  table_open_cache =
125 tables table_definition_cache = 256 tables You have a total
of 97 tables You have 125 open tables. Current table_cache hit
rate is 3%  Earlier temp table was "of the 23725 temp tables 38%
were created on disk" but I changed max_heap and tmp_table to
200m from 16m and it lowered to 30%..   engine myisam
group_concat_max_len = 32768 key_buffer_size = 3.7 GB,
thread_stack = 256k, table_cache = 125 query_cache_limit = 1M
query_cache_size = 16M join_buffer_size = 2.00 M max_connections
= 800  Another system with default configuration is showing "of
23725 temp tables, 1% were created on disk" with the same
database.  I tried changing to default on the machine with this
issue and it still shows "Of 580 temp tables, 16% were created
on disk".  I am using Ubuntu 11.4 64