Transactions, Isolation, and Recovery

Status Draft outlineSection Storage and Database Internals

Transactions define which intermediate states may be observed and how committed state survives failure. Isolation and durability require distinct mechanisms.

Planned model

Interleave reads and writes under locking and multiversion concurrency control. Inject crashes around log, data-page, commit, and checkpoint events.

Questions

• Which anomalies does each isolation level permit?
• What ordering between WAL and data pages enables recovery?
• How are abandoned versions or locks cleaned up?

Exercise

Construct one write-skew history and show which isolation rule prevents it.