Showing entries 1 to 1
Displaying posts with tag: derived_merge (reset)
Back on disk temporary tables

We already blog a lot on temporary tables on disk, how this could be bad for your workload and should be avoid.  Each temporary table will open a file descriptor,  external kernel call and by nature a well know file system slow operation.

We can point this benchmark simulating a working mail server

Monitoring of such queries can be trace via the status of

Evidence of what is happening watching many Aria or MyISAM tables created on disk :

/usr/sbin/lsof  | grep "mysql" | grep "#"
mysqld     1855     mysql 1658u      REG                8,1       8192    1505932 …

[Read more]
Showing entries 1 to 1