Built transactional operations on a single node with full ACID guarantees. This is where we start building real database-like features.
Transactions: Atomic read/write operations
Isolation: Transactions don't interfere with each other
Consistency: Operations maintain data integrity
Durability: Committed transactions persist
In-memory transaction log
Version-based concurrency control
Atomic commit/rollback semantics
Simple two-phase transaction protocol
Begin: Start a new transaction
Read: Read values within transaction context
Write: Buffer writes until commit
Commit: Apply all buffered writes atomically
Rollback: Discard all transaction changes
Optimistic Concurrency: Assume no conflicts initially
Version Vectors: Track read/write sets for conflict detection
Local Atomicity: Single-node makes commit simple
Write Buffering: Defer writes until commit
Atomicity: All operations in transaction succeed or fail together
Consistency: Transactions maintain data invariants
Isolation: Concurrent transactions don't interfere
Durability: Committed changes persist
Single node eliminates distributed coordination
In-memory operations are fast and atomic
Version tracking enables optimistic concurrency
Simple conflict detection and resolution
This foundation sets us up for multi-node distributed transactions - once we have solid single-node ACID, we can think about distributed ACID.