Learn PostgreSQL Isolation Levels for Secure Transactions

This resource offers a total of 60 PostgreSQL Isolation levels problems for practice. It includes 12 main exercises, each accompanied by solutions, detailed explanations, and four related problems.

Following exercises illustrate various methods to set and use isolation levels in PostgreSQL transactions, ensuring data consistency and controlling concurrent access.

1. Set Transaction Isolation Level to READ COMMITTED

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

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2. Set Transaction Isolation Level to REPEATABLE READ

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

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3. Set Transaction Isolation Level to SERIALIZABLE

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

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4. Set Session Default Isolation Level

Write a PostgreSQL query to set the default transaction isolation level for the session to REPEATABLE READ.

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5. Begin Transaction with Custom Isolation Level for Multiple Operations

Write a PostgreSQL query to start a transaction with a custom isolation level and perform several operations before committing.

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6. Read Latest Committed Data in READ COMMITTED Mode

Write a PostgreSQL query to illustrate how a transaction operating in READ COMMITTED isolation level reads the latest committed data.

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7. Consistent Snapshot in REPEATABLE READ Mode

Write a PostgreSQL query to demonstrate that a transaction in REPEATABLE READ mode returns a consistent snapshot of data.

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8. Handling Serialization Errors in SERIALIZABLE Mode

Write a PostgreSQL query to simulate a transaction that may encounter a serialization error under SERIALIZABLE isolation.

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9. Using Isolation Level to Prevent Dirty Reads

Write a PostgreSQL query to demonstrate that setting an isolation level prevents dirty reads by updating and then selecting data in a transaction.

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10. Simulating Concurrent Transactions with Different Isolation Levels

Write a PostgreSQL query example to illustrate two concurrent transactions—one using READ COMMITTED and another using REPEATABLE READ.

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11. Preventing Lost Updates with REPEATABLE READ

Write a PostgreSQL query to demonstrate how REPEATABLE READ can help prevent lost updates in a concurrent environment.

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12. Reset Session Isolation Level to Default

Write a PostgreSQL query to reset the session's transaction isolation level back to the default (typically READ COMMITTED).

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More to Come !

Do not submit any solution of the above exercises at here, if you want to contribute go to the appropriate exercise page.