Locks in Database | Types of Locks in DBMS

Locks in Database are connected to the locking protocols that are performed in DBMS for the control and supervision of concurrency control, which is a method to perform instant procedures but without bothering with each other. In the transaction process, various transactions may request for a lock on a data record object concurrently. Therefore, for this, we require a tool for controlling the locking calls through the DBMS transactions. This type of tool is appreciated to be a Lock manager.

This DBMS Lock depends on the way of message short where the transactions and lock handler shift messages to control the locking as well as unlocking of the data record items. In this mechanism, the expected data structure used for locking the DBMS transaction method is known to be the Lock table where hashing index is performed.

Syntax:

DBMS Locks engine has the following syntax formation for operating in DBMS table data and reaching the table rows and columns as well:

Database Locks offers three levels for the lock procedure which are mentioned below:

1. Row Level Locking:

The row-level locking is performed if the condition were calculated to only a single table row. In this type of page-level locking, the locking protocol is completed of the clause WHERE assesses to a group of data.

2. Page-Level Locking:

In this type of page-level locking, the locking protocol is performed of the clause WHERE assesses to a group of data.

3. Table Level Locking:

This type of table locking is applied if the WHERE clause is removed and the query will reach the whole table. But when the update is executed by another user the update can not do for the entire table. Following is the syntax code for the same.

LOCK TABLE <name_of_table> [<name_of_table>]….IN {ROW EXCLUSIVE / ROW SHARE / SHARE UPDATE / EXCLUSIVE / SHARE ROW EXCLUSION / SHARE } [NOWAIT]

Locks in Database Management System

In DBMS, the lock is a mechanism used for validating data integrity. In Oracle, the engine locks j table data automatically while executing the SQL query commands such as Insert/ Select/ Delete/ Update. This N kind of locking represents implicit locking. In common, the DBMS looks are of 2 types as mentioned below:

• Shared Locks
• Binary Locks

Shared Locks in Database

The shared locks in Database Management System are placed on resources at whatever time a read operation such as the SELECT command is performed. Various shared locks can be set on a store concurrently.

Binary Locks

This Binary lock implemented on a data item is bound to deliver two events either locked or unlocked. Here, a separate lock may be related to every database item suppose N, if the 1 is the value of the lock on N, then the N item will not be obtained when asked by any database performance. Furthermore, when the value is 0 on N then, the data item can be obtained on appeal.

Example

Let’s consider an example to explain the DBMS Locks explained as follows considering the transaction process that happened to take the database tables. Before continuing forwards, we will perform a details table to practice with the locking of table declarations as,

CREATE TABLE details (
id INT NOT NULL AUTO_INCREMENT,
detail VARCHAR(100) NOT NULL,
PRIMARY KEY (id)
);

Output

In MySQL, the table can be locked with the mentioned query code that provides the table lock explicitly:

LOCK TABLES name_of_table [WRITE | READ];

The syntax code above classifies the table name that one wants to lock either with type READ or WRITE. Thus, for unlocking those tables we can deliver the table as follows:

UNLOCK TABLES;

Let’s review the READ operation type to show how lock-in DBMS works. For this action, we will check the relationship id present by the SQL query as,

LOCK TABLES name_of_table [WRITE | READ];

Conclusion

In DBMS, we have many ways based on protocols that happened for the concurrency control that passes many advantages for controlling the hanging amount which they require. DBMS Locks benefits to manage serializability to resolve the disputes caused among the synchronized transactions. These lock-based protocols present a tool where the transaction can not write or read the data record except it wins an appropriate lock.