Wait... why?
Admittedly I'm mostly using MSSQL, but joining multiple tables seems a pretty natural thing to do (assuming you are joining on well indexed tables).
Admittedly I'm mostly using MSSQL, but joining multiple tables seems a pretty natural thing to do (assuming you are joining on well indexed tables).
This is specific to the default MyISAM engine, where it locks all tables used in a query for the duration of the query. So two queries that touch the same table can't run concurrently.
You may never hit this as a problem if your queries are fast enough, but it is something to be aware of.
InnoDB uses row-level locks, so it's extremely unlikely to cause such issues.