Built transactional operations on a single node with full ACID guarantees. This is where we start building real database-like features.
What it Does
- Transactions: Atomic read/write operations
- Isolation: Transactions don't interfere with each other
- Consistency: Operations maintain data integrity
- Durability: Committed transactions persist
The Implementation
- In-memory transaction log
- Version-based concurrency control
- Atomic commit/rollback semantics
- Simple two-phase transaction protocol
Transaction Operations
- 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
Key Design Choices
- 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
ACID Properties
- Atomicity: All operations in transaction succeed or fail together
- Consistency: Transactions maintain data invariants
- Isolation: Concurrent transactions don't interfere
- Durability: Committed changes persist
Why This Works
- 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.
