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#1 (**permalink**) 02-28-2008, 07:35 AM

Hi

I'm using a java application with mysql 4.0.2
when I issue "show processlist", I can see serveral query locked.
I didn't lock query from my java code, but some query are locked....

I don't know why query are locked...
What make it loked query of mysql 4.0.2 ?

Any comment will help me.

Have a day.

#2 (**permalink**) 02-28-2008, 07:35 AM

Hi there.
A number of reasons can lead to locked query appearence in processlist.
Here's the link where mySQL locking is described in general, i guess
http://dev.mysql.com/doc/refman/4.1/...ng-issues.html

Other words, queries can be locked because the need resources (i.e. a
single row for innodb tables and whole table fo myisam tables) which is
used by someone else now.

I.e. in one your session you issue
mysql> select last_name, first_name from emp where emp_id = 12 for
update;
and then in parallel session you say
update emp set department_id = 'Sales' where emp_id = '12';

Second query will wat until the first session either commited or rolled
back.

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