Isolation level in SQL SERVER

 

Ø  Isolation levels determine how a transaction interacts with other concurrent transactions accessing the same data.

Ø  SQL Server has four isolation levels: Read Uncommitted, Read Committed, Repeatable Read, and Serializable.

Ø  Each isolation level provides a different balance between data accuracy, consistency, concurrency, and performance.

Ø  It's important to choose the right isolation level for your transactions based on your specific requirements and potential concurrency issues.

Ø  You should carefully consider the trade-offs between data accuracy, consistency, concurrency, and performance when choosing an isolation level.

Ø  SQL Server allows you to change the isolation level at any time during a transaction using the SET TRANSACTION ISOLATION LEVEL statement.

Isolation Level	Description	Example
Read Uncommitted	Allows transactions to read data that has been modified by other transactions but not yet committed.	Running reports that can tolerate dirty reads
Read Committed	Allows transactions to read data that has been committed by other transactions, but not data that has been modified but not yet committed.	An e-commerce website where multiple customers may be placing orders at the same time
Repeatable Read	Ensures that a transaction can read the same data multiple times and get the same results each time, by placing shared locks on all data read by the transaction.	A financial application where multiple users may be updating account balances at the same time
Serializable	Ensures that a transaction can read and modify data as if it is the only transaction running, by placing range locks on all data read by the transaction.	A reservation system where multiple users may be reserving the same seats at the same time