mysql - Unlocking tables if thread is lost

Question

http://dev.mysql.com/doc/refman/5.0/en/internal-locking.html

The following is the extract from the documentation.

mysql> LOCK TABLES real_table WRITE, temp_table WRITE;
mysql> INSERT INTO real_table SELECT * FROM temp_table;
mysql> DELETE FROM temp_table;
mysql> UNLOCK TABLES;

My question is that if I use this logic in the shell script code, and if the thread is lost (not killed) before it reaches "unlock tables" statement, how will I know that some tables are locked and how do I unlock tables manually?

Answer 1

Here's what i do to FORCE UNLOCK FOR some locked tables in MySQL

1) Enter MySQL

mysql -u your_user -p

2) Let's see the list of locked tables

mysql> show open tables where in_use>0;

3) Let's see the list of the current processes, one of them is locking your table(s)

mysql> show processlist;

4) Let's kill one of these processes

mysql> kill put_process_id_here;