Master Hibernate and JPA with Spring Boot in 100 Steps - Step 61 - Understand 4 Isolation Levels

The video tutorial explains the four different isolation levels in database transactions: read uncommitted, read committed, repeatable read, and serializable. Each level addresses specific problems such as dirty reads, non-repeatable reads, and phantom reads. Read uncommitted allows all transactions to read any data, leading to potential dirty reads. Read committed prevents dirty reads by allowing only committed data to be read. Repeatable read locks both modified and read data, preventing dirty and non-repeatable reads. Serializable, the strictest level, prevents all three problems by locking the entire table or specific constraints during a transaction. The tutorial concludes with a brief overview of the isolation levels and hints at further discussion on their consequences.

Which isolation level allows transactions to read uncommitted data, potentially leading to dirty reads?

• Serializable

• Repeatable Read

• Read Uncommitted

• Read Committed

What is the main advantage of the Read Committed isolation level?

• It allows phantom reads.

• It allows dirty reads.

• It prevents dirty reads by only allowing committed data to be read.

• It locks the entire table during a transaction.

Which isolation level would you choose to prevent dirty reads but allow non-repeatable reads and phantom reads?

• Read Committed

• Read Uncommitted

• Repeatable Read

• Serializable

How does the Repeatable Read isolation level ensure data consistency?

• By allowing non-repeatable reads.

• By locking both modified and read data during a transaction.

• By locking only modified data.

• By allowing dirty reads.

Which isolation level is the strictest and prevents all three problems: dirty reads, non-repeatable reads, and phantom reads?

• Serializable

• Repeatable Read

• Read Committed

• Read Uncommitted

In the Serializable isolation level, what happens when a transaction starts with a query that has specific constraints?

• Only the modified rows are locked.

• The entire table is locked.

• No locks are applied.

• A lock is created for any row matching the constraints.

What is a potential downside of using the Serializable isolation level?

• It does not prevent phantom reads.

• It allows dirty reads.

• It can lead to reduced concurrency due to extensive locking.

• It allows non-repeatable reads.