Using SERIALIZABLE Isolation Level in MySQL

Set Isolation Level to Serializable

Write a MySQL query to set the isolation level to SERIALIZABLE and perform a read operation.

Solution:

-- Set the transaction isolation level to SERIALIZABLE:
-- This ensures the highest level of isolation, preventing dirty reads, non-repeatable reads, and phantom reads.
SET TRANSACTION ISOLATION LEVEL SERIALIZABLE;

-- Begin a new transaction
START TRANSACTION;

-- Select all employees from DepartmentID = 2:
-- Under SERIALIZABLE isolation, this query locks the relevant rows or even the whole table (depending on the database system).
-- No other transaction can modify or insert new rows in the same range until this transaction is complete.
SELECT * FROM Employees WHERE DepartmentID = 2;

-- Commit the transaction:
-- Since there are no data modifications (only a SELECT statement), this step ensures the transaction is properly closed.
COMMIT;

Explanation:

• Purpose of the Query:
• The goal is to ensure the highest level of isolation, preventing phantom reads.
• This demonstrates the use of the SERIALIZABLE isolation level.
• Key Components:
• SET TRANSACTION ISOLATION LEVEL SERIALIZABLE: Sets the strictest isolation level.
• SELECT * FROM Employees: Reads data from the Employees table.
• Why use Isolation Levels?:
• Isolation levels control the visibility of changes made by other transactions, ensuring data consistency.
• Real-World Application:
• For example, in a banking system, you might use READ COMMITTED to ensure that only finalized transactions are visible.

For more Practice: Solve these Related Problems:

• Write a MySQL query to perform a complex multi-table join under SERIALIZABLE isolation.
• Write a MySQL query to demonstrate how SERIALIZABLE prevents phantom reads.
• Write a MySQL query to compare the execution time of SERIALIZABLE transactions with lower isolation levels.
• Write a MySQL query to handle a long-running transaction using SERIALIZABLE isolation.

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• Master MySQL Transactions and Concurrency Exercises Home. ↩
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