Databases Demystified Chapter 5 – Transactions Part 2

This text discusses the relationship between isolation and concurrency in modern databases. It explains how parallel processing can lead to race conditions, where two processes try to change the same data simultaneously, resulting in unpredictable outcomes. Common race conditions include dirty reads, non-repeatable reads, and phantom reads. To prevent these issues, databases use isolation levels that determine how much isolation transactions have from each other. The four widely recognized isolation levels are Serializable, Repeatable Reads, Read Committed, and Read Uncommitted, with the former being the most strict and the latter being the least strict. Locks are used to implement isolation in databases, allowing only one transaction at a time to access certain data. However, excessive locking can lead to deadlocks and reduced performance. Balancing isolation levels and speed is crucial for ensuring both accurate data and fast application response times.