Backend Developer
Transactions and locking questions
23 questions on Transactions and locking for backend developers, easiest first.
Easy 2
Medium 10
- Isolation levels and dirty readsmedium
- What a dirty read ismedium
- The same row read twice gives two valuesmedium
- PostgreSQL's default isolation levelmedium
- MySQL InnoDB's default isolation levelmedium
- FOR UPDATE that locks nothing usefulmedium
- Several workers taking jobs from a tablemedium
- One query escapes the transactionmedium
- A Redis transaction does not roll backmedium
- Job runs before the row existsmedium
Hard 11
- Lost update on a wallet balancehard
- Saving to DB and publishing an eventhard
- Deadlocks between two transfershard
- Two doctors go off call at oncehard
- A transaction spread across connectionshard
- Errors under Serializable isolationhard
- Deadlocks in money transfershard
- Order saved but event never senthard
- Transactions fail on a local MongoDBhard
- One write escapes a MongoDB transactionhard
- The connection dropped during COMMIThard