Transactions and isolation levels explained

What you’ll learn here

Transactions and isolation levels are where “it works on my machine” turns into production reality. This quiz helps you connect theory (ACID, anomalies) with what databases actually do under concurrent load.

Each question is multiple-choice with 4 options and no timer, so you can think through schedules, locks, and visibility rules without rushing.

Skills you’ll practice

You’ll practice identifying which isolation level prevents which anomaly, reasoning about concurrent transactions, and choosing safe patterns for reads and writes. Expect a mix of definitions, applied scenarios, and “what happens if…” debugging questions.

To tailor the experience, choose your preferred question count and difficulty before starting—short sets for quick refreshers, or longer runs to build endurance across mixed topics.

Common pitfalls (and how this quiz targets them)

Many learners mix up non-repeatable reads vs phantom reads, or assume “Serializable” always means table locks. The questions repeatedly contrast similar concepts so you build reliable mental checkpoints.

Another frequent trap is confusing MVCC behavior with lock-based isolation; several items focus on visibility, snapshots, and write conflicts to clarify the differences.

How difficulty is balanced

Difficulty is mixed on purpose: easier questions reinforce core vocabulary, while harder ones simulate real concurrency bugs and trade-offs. This balance keeps the quiz approachable while still challenging experienced developers.

• Map dirty/non-repeatable/phantom reads to the isolation levels that prevent them
• Recognize when locking, MVCC snapshots, or write skew can occur
• Choose safe transaction boundaries and understand autocommit implications
• Interpret practical outcomes of Read Committed vs Repeatable Read vs Serializable
• Spot misleading assumptions about “consistent reads” under concurrency