Any way to select without causing locking in MySQL?

Question

Query:

SELECT COUNT(online.account_id) cnt from online;

But online table is also modified by an event, so frequently I can see lock by runn

Answer 1

If the table is InnoDB, see http://dev.mysql.com/doc/refman/5.1/en/innodb-consistent-read.html -- it uses consistent-read (no-locking mode) for SELECTs "that do not specify FOR UPDATE or LOCK IN SHARE MODE if the innodb_locks_unsafe_for_binlog option is set and the isolation level of the transaction is not set to SERIALIZABLE. Thus, no locks are set on rows read from the selected table".