Obtain an Exclusive Lock on the Entire Table

Lock an Entire Table Using LOCK TABLE

Write a PostgreSQL query to lock an entire table to prevent any concurrent data modifications.

Solution:

-- Lock the Employees table in ACCESS EXCLUSIVE mode.
LOCK TABLE Employees IN ACCESS EXCLUSIVE MODE; -- Prevents all concurrent reads and writes.

Explanation:

• Purpose of the Query:
• The goal is to acquire an exclusive lock on the table, blocking all other operations until released.
• This demonstrates the use of the LOCK TABLE command for table-level locking.
• Key Components:
• LOCK TABLE Employees : Specifies the table to be locked.
• IN ACCESS EXCLUSIVE MODE : The highest lock level that prevents any other access.
• Real-World Application:
• Useful during schema changes or critical batch updates where no concurrent access is desired.

Notes:

• Table-level locks can impact performance; use them only when necessary.
• This lock type blocks both reads and writes from other transactions.

For more Practice: Solve these Related Problems:

• Write a PostgreSQL query to lock the entire Orders table in ACCESS EXCLUSIVE mode to prepare for a bulk update.
• Write a PostgreSQL query to lock the Customers table in SHARE MODE to allow reads but block writes during maintenance.
• Write a PostgreSQL query to lock the Inventory table in ROW EXCLUSIVE mode to update stock levels without interfering with other sessions.
• Write a PostgreSQL query to lock the Employees table in ACCESS EXCLUSIVE mode prior to a major schema change.

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