Under the hood mechanics of Multi-Version Concurrency Control, transaction isolation anomalies, 2PL, index types, deadlock detection, and cost-based query optimization.
MVCC (Multi-Version Concurrency Control)
Isolation Levels & Anomalies Matrix
ANSI SQL & Snapshot Isolation Anomalies
Isolation Level
Dirty Read
Non-Repeatable Read
Phantom Read
Write Skew
Read Uncommitted
Allowed
Allowed
Allowed
Allowed
Read Committed
Prevented
Allowed
Allowed
Allowed
Repeatable Read
Prevented
Prevented
Allowed (SQL Standard)
Allowed
Snapshot Isolation
Prevented
Prevented
Prevented
Allowed
Serializable (SSI)
Prevented
Prevented
Prevented
Prevented
Locking & Concurrency Control
Deadlock Detection & Prevention
Cost-Based Query Optimizer (CBO)
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