What are the characteristics of the three types of locks in MySQL?

The three common types of locks in MySQL are shared lock (S-lock), exclusive lock (X-lock), and intention lock (IS-lock and IX-lock).

1. Shared lock (S lock):

1. Shared locks are used for read operations, multiple transactions can hold shared locks simultaneously without interfering with each other.
2. A shared lock prevents other transactions from obtaining an exclusive lock but allows other transactions to obtain a shared lock.
3. Shared locks do not block read operations for other transactions, but they do block write operations for other transactions.

1. Exclusive lock (X lock)

1. Exclusive lock is used for write operations, where only one transaction can hold the exclusive lock.
2. Exclusive locks prevent other transactions from obtaining shared locks and exclusive locks.
3. The exclusive lock will block the read and write operations of other transactions.

1. Intent locks (IS lock and IX lock):

1. An intent lock is a type of auxiliary lock used for table-level locking, rather than directly locking data rows.
2. The IS lock indicates that a transaction is preparing to acquire a shared lock on a table, preventing other transactions from acquiring an exclusive lock on that table.
3. IX lock indicates a transaction preparing to acquire an exclusive lock on a table, preventing other transactions from acquiring shared and exclusive locks on that table.
4. Intent locks do not block read operations of other transactions but do block write operations of other transactions.

These locks can determine whether concurrent operations and data consistency are allowed based on the transaction isolation level. Different locks can be used in different scenarios to meet the requirements of data consistency and concurrency.