Execute Transactions Using READ COMMITTED Level

Set Transaction Isolation Level to READ COMMITTED

Write a PostgreSQL query to set the transaction isolation level to READ COMMITTED for a transaction.

Solution:

-- Begin the transaction and set isolation level to READ COMMITTED.
BEGIN;
SET TRANSACTION ISOLATION LEVEL READ COMMITTED;
-- (Perform transactional operations here)
COMMIT;

Explanation:

• Purpose of the Query:
• The goal is to ensure that the transaction only sees data committed before each query execution.
• This demonstrates how to explicitly set the isolation level to READ COMMITTED for a transaction.
• Key Components:
• BEGIN; : Starts the transaction.
• SET TRANSACTION ISOLATION LEVEL READ COMMITTED; : Specifies the isolation level.
• COMMIT; : Finalizes the transaction.
• Real-World Application:
• Used when you require a balance between data consistency and concurrency, typical for many OLTP systems.

Notes:

• READ COMMITTED is PostgreSQL's default isolation level.
• This level prevents dirty reads while allowing non-repeatable reads and phantom reads.

For more Practice: Solve these Related Problems:

• Write a PostgreSQL query to update the last login timestamp in the Users table within a transaction using READ COMMITTED isolation.
• Write a PostgreSQL query to insert a new order into the Orders table within a transaction set to READ COMMITTED isolation.
• Write a PostgreSQL query to delete expired sessions from the Sessions table in a transaction using READ COMMITTED isolation.
• Write a PostgreSQL query to select the latest records from the Logs table within a transaction operating in READ COMMITTED mode.

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