Transaction Isolation
Everything on SkillVeris tagged Transaction Isolation — collected across the glossary, study notes, blog, and cheat sheets.
11 resources across 1 library
Interview Questions(11)
What is the Read Uncommitted Isolation Level?
Read Uncommitted is the weakest transaction isolation level, allowing a transaction to see changes made by other transactions even before those changes are com…
What is the Read Committed Isolation Level?
Read Committed is an isolation level that guarantees a transaction only ever sees data that has been committed by other transactions, eliminating dirty reads w…
What is the Repeatable Read Isolation Level?
Repeatable Read is an isolation level that guarantees any row a transaction has read will return the exact same values if read again later in that same transac…
What is the Serializable Isolation Level?
Serializable is the strictest transaction isolation level, guaranteeing that the outcome of running transactions concurrently is identical to running them one…
What is a Phantom Read in Database Transactions?
A phantom read is a concurrency anomaly where a transaction re-runs a range query and finds a different set of rows than the first time, because another transa…
Dirty Read vs Non-Repeatable Read: What is the Difference?
A dirty read happens when a transaction reads data written by another transaction that has not yet committed, so it can read a value that later gets rolled bac…
What is MVCC (Multi-Version Concurrency Control)?
MVCC (Multi-Version Concurrency Control) is a concurrency-control technique where the database keeps multiple versions of a row so readers see a consistent sna…
What is the Write Skew Anomaly?
Write skew is a concurrency anomaly where two transactions each read overlapping data, independently decide their own write is safe based on what they read, an…
What is the Lost Update Problem in Databases?
The lost update problem occurs when two transactions read the same row, both compute a new value based on that same original read, and the second transaction’s…
What is the Two-Phase Locking (2PL) Protocol?
Two-Phase Locking (2PL) is a concurrency-control protocol that guarantees serializable execution by splitting every transaction into a growing phase, where it…
How Does Optimistic Concurrency Control Work With Version Columns?
Optimistic concurrency control uses a version (or updated_at) column on each row so an UPDATE only succeeds if the version read by the client still matches the…