How to share read lock in mysql

Explanation

1. The read operation of the MyISAM table (adding a reading lock) will not prevent other processes from reading the same table, but it will prevent the writing operation of the same table.

2. Only after the read lock is released, writing operations of other processes can be performed. No other tables can be accessed before the lock is released.

Example

Transaction-A
mysql> lock table myisam_lock read;
Query OK, 0 rows affected (0.00 sec)
 
mysql> select * from myisam_lock;
9 rows in set (0.00 sec)
 
mysql> select * from innodb_lock;
ERROR 1100 (HY000): Table 'innodb_lock' was not locked with LOCK TABLES
 
mysql> update myisam_lock set v='1001' where k='1';
ERROR 1099 (HY000): Table 'myisam_lock' was locked with a READ lock and can't be updated
 
mysql> unlock tables;
Query OK, 0 rows affected (0.00 sec)

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