Read Committed Isolation

Read Committed is a transaction isolation level in database systems that ensures a transaction only reads data that has been committed by other transactions, preventing dirty reads. It allows non-repeatable reads and phantom reads, meaning data can change between reads within the same transaction if other transactions commit changes. This level balances consistency and concurrency by providing basic data integrity while allowing higher performance in multi-user environments.

Also known as: Read Committed, RC, Read Committed Level, Read Committed Isolation Level, RC Isolation

Why learn Read Committed Isolation?

Developers should use Read Committed isolation when building applications that require moderate data consistency without the overhead of stricter isolation levels, such as in web applications with high concurrency where occasional non-repeatable reads are acceptable. It is commonly the default isolation level in databases like PostgreSQL and SQL Server, making it essential for ensuring data integrity in transactional systems while avoiding deadlocks and performance bottlenecks associated with serializable isolation.

Learning Resources

• docs: PostgreSQL Documentation: Transaction Isolation
• docs: Microsoft SQL Server Docs: SET TRANSACTION ISOLATION LEVEL
• book: Database System Concepts: Isolation Levels
• video: YouTube: Understanding Database Isolation Levels
• course: Coursera: Database Management Essentials