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Designing Data-Intensive Applications: The Big Ideas Behind Reliable, Scalable, and Maintainable Systems

Distributed Systems System Design Databases Architecture Book Notes Scalability

A comprehensive technical deep-dive into the fundamental principles of building robust data systems at scale, inspired by Martin Kleppmann's seminal work.

Martin Kleppmann’s “Designing Data-Intensive Applications” helps us understand the fundamental trade-offs that every distributed system designer faces: consistency vs. availability, latency vs. throughput, and complexity vs. simplicity.

In this technical deep-dive, I’ll explore the core concepts that make data-intensive applications reliable, scalable, and maintainable. We’ll go beyond surface-level explanations to understand the underlying principles that govern modern data systems.

The Three Pillars: Reliability, Scalability, and Maintainability

Reliability: The Foundation of Trust

Reliability is the system’s ability to continue functioning correctly even when things go wrong. In large-scale systems, failures are not exceptional—they’re the norm.

Hardware Faults

  • Disk failures: With 10,000 disks, expect daily failures
  • Memory corruption: ECC memory helps, but cosmic rays still cause bit flips
  • Network partitions: Temporary network issues that split clusters
  • Power failures: UPS systems and graceful shutdown procedures

Software Faults

  • Bugs: Even well-tested code has edge cases
  • Resource leaks: Memory leaks, file descriptor exhaustion
  • Cascading failures: One failure triggering others
  • Clock drift: NTP synchronization issues in distributed systems

Human Errors

  • Configuration mistakes: Wrong timeout values, misconfigured load balancers
  • Deployment failures: Rolling back to previous versions
  • Operational errors: Accidentally deleting production data

Fault Tolerance Strategies

  • Redundancy: Multiple copies of critical components
  • Graceful degradation: System continues with reduced functionality
  • Circuit breakers: Prevent cascading failures
  • Chaos engineering: Proactively testing failure scenarios

Scalability: Growing Without Pain

Scalability is the system’s ability to handle increased load gracefully. Kleppmann emphasizes that scalability isn’t just about performance—it’s about the ability to add resources proportionally.

Load Parameters

  • Web applications: Requests per second, concurrent users
  • Databases: Read/write ratios, data size, query complexity
  • Batch processing: CPU time, I/O bandwidth, memory usage
  • Real-time systems: Event frequency, processing latency

Performance Characteristics

  • Throughput: Number of records processed per second
  • Response time: Time to process a single request
  • Latency percentiles: p50, p95, p99, p999
  • Tail latency: Worst-case performance matters more than average

Scaling Strategies

  • Vertical scaling: Adding more resources to a single machine
  • Horizontal scaling: Adding more machines to the cluster
  • Functional scaling: Separating different types of workloads
  • Geographic scaling: Distributing systems across regions

Scalability Patterns

  • Load balancing: Distributing requests across multiple servers
  • Caching: Reducing load on backend systems
  • Asynchronous processing: Handling non-time-critical operations
  • Database sharding: Distributing data across multiple databases

Maintainability: The Long Game

Maintainability ensures that engineers can work on the system productively over time. This is often overlooked but critical for long-term success.

Operability

  • Monitoring: Comprehensive metrics and alerting
  • Deployment: Automated, safe deployment processes
  • Troubleshooting: Clear logging and debugging tools
  • Documentation: Up-to-date operational procedures

Simplicity

  • Abstraction: Hiding complexity behind clean interfaces
  • Modularity: Breaking systems into manageable components
  • Consistency: Using similar patterns throughout the system
  • Elimination: Removing unnecessary features and complexity

Evolvability

  • Backward compatibility: New versions work with old data
  • Schema evolution: Changing data structures safely
  • API versioning: Managing interface changes
  • Feature flags: Gradual rollout of new functionality

Data Models and Query Languages

The Relational Model: Mathematical Foundation

The relational model’s greatest strength is its mathematical foundation in set theory and predicate logic. This provides:

Mathematical Properties

  • Set operations: Union, intersection, difference, Cartesian product
  • Relational algebra: Selection, projection, join operations
  • Functional dependencies: Normalization theory
  • ACID transactions: Atomicity, consistency, isolation, durability

SQL Advantages

  • Declarative: Describe what you want, not how to get it
  • Query optimization: Database chooses efficient execution plans
  • ACID guarantees: Transactional consistency
  • Schema enforcement: Data integrity constraints

Normalization Trade-offs

  • First Normal Form (1NF): Atomic values, no repeating groups
  • Second Normal Form (2NF): No partial dependencies
  • Third Normal Form (3NF): No transitive dependencies
  • Boyce-Codd Normal Form (BCNF): Every determinant is a candidate key

Document Model: Schema Flexibility

Document databases (MongoDB, CouchDB) offer different trade-offs:

Advantages

  • Schema flexibility: Fields can be added/removed without migrations
  • Better locality: Related data stored together
  • Elimination of joins: Data is denormalized
  • Natural mapping: Objects map directly to application code

Challenges

  • Referential integrity: No foreign key constraints
  • Complex queries: Limited support for joins and aggregations
  • Schema evolution: No built-in schema validation
  • Transaction support: Limited multi-document transactions

Use Cases

  • Content management: Blog posts, articles, product catalogs
  • Real-time analytics: Event data, user behavior tracking
  • Mobile applications: Offline-first data synchronization
  • IoT data: Time-series data with varying schemas

Graph Models: Complex Relationships

When relationships become complex, graph models excel:

Property Graphs

  • Nodes: Entities with properties
  • Edges: Relationships with properties
  • Labels: Categorizing nodes and edges
  • Indexes: Fast traversal of specific patterns

Triple Stores

  • Subject: The entity being described
  • Predicate: The relationship or property
  • Object: The value or related entity
  • RDF: Resource Description Framework standard

Graph Algorithms

  • Shortest path: Finding optimal routes
  • PageRank: Measuring node importance
  • Community detection: Identifying clusters
  • Recommendation: Finding similar entities

Use Cases

  • Social networks: Friend relationships, content sharing
  • Knowledge graphs: Semantic relationships, ontologies
  • Fraud detection: Identifying suspicious patterns
  • Recommendation systems: Finding related items

Storage and Retrieval

Log-Structured Storage: The Power of Append-Only

The log is the most fundamental data structure in computing. It’s append-only, immutable, and provides a complete audit trail.

Write-Ahead Logging (WAL)

  • Durability guarantee: Changes logged before acknowledgment
  • Crash recovery: Replay log to restore state
  • Performance: Sequential writes are much faster than random writes
  • Implementation: fsync() calls ensure disk persistence

Replication Logs

  • Change propagation: Shipping changes to followers
  • Ordering: Maintaining operation sequence across nodes
  • Conflict resolution: Handling concurrent modifications
  • Lag monitoring: Tracking replication delays

Event Sourcing

  • Complete history: All changes stored as events
  • Temporal queries: Understanding system state at any point
  • Audit trails: Compliance and debugging requirements
  • State reconstruction: Deriving current state from events

Log Compaction

  • Space efficiency: Removing obsolete entries
  • Recovery speed: Starting from recent snapshots
  • Compaction strategies: Size-tiered, leveled, time-windowed
  • Garbage collection: Managing log growth

B-Trees: The Workhorse of Relational Databases

B-trees have been the foundation of relational databases for decades:

Structure

  • Balanced tree: All leaf nodes at same level
  • Page-based: Nodes aligned with disk sectors (typically 4KB)
  • Key ordering: Sorted keys for efficient range queries
  • Fan-out: High branching factor minimizes tree height

Operations

  • Search: O(log n) complexity with good cache locality
  • Insert: Split nodes when they become full
  • Delete: Merge nodes when they become too empty
  • Range queries: Efficient traversal of key ranges

Optimizations

  • Prefix compression: Sharing common key prefixes
  • Suffix truncation: Removing unnecessary key parts
  • Bulk loading: Efficient initial tree construction
  • Write optimization: Minimizing disk I/O

Write Amplification

  • In-place updates: Modifying existing pages
  • Page splits: Creating new pages during inserts
  • Rebalancing: Maintaining tree balance
  • Logging overhead: WAL and checkpoint operations

LSM-Trees: Write-Optimized Storage

Log-Structured Merge Trees optimize for write-heavy workloads:

Components

  • Memtable: In-memory buffer for recent writes
  • SSTables: Immutable sorted string tables on disk
  • Bloom filters: Probabilistic membership tests
  • Compaction: Background merging of SSTables

Write Path

  • Buffering: Writes accumulate in memtable
  • Flushing: Memtable flushed to disk when full
  • Sorting: Keys sorted within each SSTable
  • Indexing: Creating metadata for fast lookups

Read Path

  • Bloom filter: Quick check if key might exist
  • Memtable check: Look in recent writes first
  • SSTable search: Binary search within sorted files
  • Merge logic: Combining results from multiple levels

Compaction Strategies

  • Size-tiered: Merging files of similar sizes
  • Leveled: Maintaining sorted runs at each level
  • Time-windowed: Partitioning by time
  • Hybrid approaches: Combining multiple strategies

Trade-offs

  • Write performance: Excellent for high-write workloads
  • Read performance: Multiple SSTable lookups required
  • Space amplification: Multiple copies during compaction
  • Write amplification: Background compaction overhead

Encoding and Evolution

Data Formats: Choosing the Right Representation

Different formats offer different trade-offs:

JSON

  • Human-readable: Easy to debug and inspect
  • Schema-less: Flexible structure evolution
  • Verbose: Larger size compared to binary formats
  • Parsing overhead: Slower than binary formats

Protocol Buffers

  • Compact: Efficient binary encoding
  • Schema evolution: Forward/backward compatibility
  • Code generation: Type-safe language bindings
  • Validation: Runtime schema checking

Avro

  • Schema resolution: Runtime schema evolution
  • Compact: Efficient binary encoding
  • Dynamic typing: No code generation required
  • Schema registry: Centralized schema management

MessagePack

  • JSON-compatible: Similar data model to JSON
  • Binary format: More compact than JSON
  • Fast parsing: Optimized for performance
  • Language support: Available in many languages

Schema Evolution: Managing Change Over Time

Schema evolution is critical for long-lived systems:

Compatibility Types

  • Backward compatibility: New code reads old data
  • Forward compatibility: Old code reads new data
  • Full compatibility: Both directions work
  • Breaking changes: Incompatible schema modifications

Evolution Strategies

  • Additive changes: Always add optional fields
  • Removal policies: Never remove required fields
  • Type changes: Use union types for major changes
  • Versioning: Explicit schema version management

Implementation Patterns

  • Schema registry: Centralized schema storage
  • Runtime validation: Checking data against schemas
  • Migration tools: Automated schema updates
  • Rollback procedures: Reverting to previous schemas

Best Practices

  • Plan for evolution: Design schemas with change in mind
  • Test compatibility: Verify both directions work
  • Document changes: Clear migration procedures
  • Monitor usage: Track schema adoption and issues

Replication

Leader-Based Replication: The Classic Approach

Leader-based replication is the most common strategy:

Architecture

  • Leader: Single node handling all writes
  • Followers: Receiving and applying write-ahead logs
  • Read replicas: Handling read-only queries
  • Failover: Automatic leader promotion on failure

Replication Modes

  • Synchronous: Wait for all followers to acknowledge
  • Asynchronous: Don’t wait for follower acknowledgment
  • Semi-synchronous: Wait for some followers
  • Mixed modes: Different policies for different operations

Challenges

  • Replication lag: Followers may be seconds behind
  • Failover detection: Determining when leader has failed
  • Split-brain: Multiple leaders in partitioned network
  • Consistency: Ensuring all replicas eventually converge

Solutions

  • Heartbeats: Regular leader health checks
  • Timeouts: Configurable failure detection
  • Consensus algorithms: Raft, Paxos for leader election
  • Quorum reads: Ensuring consistency across replicas

Multi-Leader Replication: Write Availability

When you need write availability across multiple data centers:

Advantages

  • Better availability: Writes succeed even if some DCs fail
  • Lower latency: Writes go to nearest data center
  • Offline operation: Local writes when disconnected
  • Geographic distribution: Global write availability

Challenges

  • Conflict resolution: Handling concurrent writes
  • Eventual consistency: Temporary inconsistencies
  • Complex topology: Managing multiple write paths
  • Monitoring: Tracking replication across DCs

Conflict Resolution Strategies

  • Last-write-wins: Simple but can lose data
  • Application-specific: Custom merge logic
  • CRDTs: Conflict-free replicated data types
  • Operational transformation: Text editing algorithms

Use Cases

  • Multi-datacenter deployments: Global applications
  • Offline-first applications: Mobile and desktop apps
  • Collaborative editing: Google Docs, Figma
  • IoT systems: Edge computing with local writes

Leaderless Replication: Dynamo-Style

Dynamo-style replication eliminates single points of failure:

Architecture

  • No leader: All nodes can handle writes
  • Quorum operations: W and R nodes must agree
  • Vector clocks: Tracking causal relationships
  • Hinted handoff: Handling temporary node failures

Quorum Configuration

  • W + R > N: Ensuring consistency
  • W = N/2 + 1: Majority writes for safety
  • R = N/2 + 1: Majority reads for consistency
  • Tunable consistency: Adjusting W and R values

Conflict Resolution

  • Vector clocks: Detecting concurrent writes
  • Last-write-wins: Using timestamps or version numbers
  • Application merge: Custom conflict resolution logic
  • CRDTs: Mathematical conflict resolution

Advantages

  • No single point of failure: Better availability
  • Lower latency: No leader coordination overhead
  • Geographic distribution: Global write availability
  • Fault tolerance: Handles arbitrary node failures

Partitioning

Partitioning Strategies: Distributing Data

Partitioning is essential for handling large datasets:

Key-Range Partitioning

  • Sorted keys: Data ordered by key values
  • Range queries: Efficient for sequential access
  • Hotspot risk: Popular key ranges can overload nodes
  • Rebalancing: Moving ranges between nodes

Hash Partitioning

  • Even distribution: Hash function spreads load evenly
  • Range query performance: Poor for sequential access
  • Rebalancing complexity: Moving individual keys
  • Consistent hashing: Minimizing data movement

Consistent Hashing

  • Virtual nodes: Improving load distribution
  • Minimal disruption: Adding/removing nodes efficiently
  • Hash ring: Circular key space
  • Replication: Multiple copies for fault tolerance

Composite Partitioning

  • Multi-level: Combining multiple strategies
  • Functional partitioning: Different data types on different nodes
  • Time-based: Partitioning by time periods
  • Hybrid approaches: Best of multiple strategies

Partitioning and Secondary Indexes

Secondary indexes introduce complexity in partitioned systems:

Local Secondary Indexes

  • Per-partition: Each partition maintains its own indexes
  • Scatter-gather: Querying all partitions for results
  • Simple maintenance: No cross-partition coordination
  • Query performance: Slower for global queries

Global Secondary Indexes

  • Cross-partition: Index spans all partitions
  • Complex maintenance: Coordinating updates across partitions
  • Better query performance: Single index lookup
  • Consistency challenges: Maintaining index consistency

Index Maintenance Strategies

  • Synchronous updates: Index updated with data
  • Asynchronous updates: Background index maintenance
  • Eventual consistency: Indexes may lag behind data
  • Bulk operations: Efficient index rebuilding

Query Routing

  • Index location: Knowing which partition has the index
  • Query planning: Optimizing multi-partition queries
  • Result aggregation: Combining results from partitions
  • Caching: Storing frequently accessed results

Transactions

ACID Properties: The Transaction Foundation

ACID transactions provide strong guarantees:

Atomicity

  • All-or-nothing: Either all operations succeed or none do
  • Rollback: Automatic cleanup on failure
  • Implementation: Undo logs or shadow pages
  • Recovery: Handling system crashes during transactions

Consistency

  • Valid state: Database moves between valid states
  • Constraints: Referential integrity, check constraints
  • Application logic: Business rules enforced
  • Invariants: System properties maintained

Isolation

  • Concurrent execution: Multiple transactions can run simultaneously
  • Serializability: Equivalent to some serial execution
  • Anomalies: Preventing race conditions
  • Locking: Controlling access to shared resources

Durability

  • Permanent storage: Committed transactions survive crashes
  • Write-ahead logging: Changes logged before acknowledgment
  • Checkpointing: Periodic state persistence
  • Recovery procedures: Restoring state after failures

Isolation Levels: Balancing Consistency and Performance

Different isolation levels offer different guarantees:

Read Uncommitted

  • No isolation: Dirty reads possible
  • Performance: No locking overhead
  • Use cases: Reporting, analytics
  • Risks: Inconsistent data, incorrect results

Read Committed

  • Basic isolation: No dirty reads
  • Non-repeatable reads: Same query may return different results
  • Implementation: Row-level locks or MVCC
  • Performance: Moderate overhead

Repeatable Read

  • Stronger isolation: No dirty or non-repeatable reads
  • Phantom reads: Range queries may return different rows
  • Implementation: Snapshot isolation
  • Use cases: Financial transactions, inventory management

Serializable

  • Strongest isolation: No anomalies possible
  • Performance impact: Higher overhead, potential deadlocks
  • Implementation: Strict two-phase locking
  • Use cases: Critical financial systems, booking systems

Common Anomalies

Dirty Read

  • Transaction A reads uncommitted data from Transaction B
  • Transaction B rolls back, leaving A with invalid data
  • Prevention: Read locks or MVCC

Non-Repeatable Read

  • Transaction A reads a row, Transaction B updates it
  • Transaction A reads the same row again, gets different data
  • Prevention: Row-level locks or snapshot isolation

Phantom Read

  • Transaction A reads a range, Transaction B inserts matching rows
  • Transaction A reads the same range again, gets additional rows
  • Prevention: Range locks or serializable isolation

Write Skew

  • Two transactions read the same data, make conflicting updates
  • Each update is valid, but combination violates constraints
  • Prevention: Serializable isolation or application-level checks

Distributed Transactions

Two-Phase Commit (2PC): The Classic Approach

2PC provides atomicity across multiple nodes:

Phase 1: Prepare

  • Coordinator sends prepare message to all participants
  • Participants perform local validation and logging
  • Participants respond with prepare/abort decision
  • Coordinator waits for all responses

Phase 2: Commit

  • If all participants prepared successfully, send commit
  • If any participant aborted, send abort to all
  • Participants perform local commit/abort
  • Coordinator waits for acknowledgments

Failure Scenarios

  • Participant failure: Coordinator can abort or retry
  • Coordinator failure: Participants may be left in uncertain state
  • Network partition: Some participants may commit, others abort
  • Timeout handling: Deciding when to abort

Problems with 2PC

  • Blocking: Participants may be blocked indefinitely
  • Performance: Multiple round trips required
  • Scalability: Coordinator becomes bottleneck
  • Recovery complexity: Handling uncertain participants

Alternative Approaches

Saga Pattern

  • Long-running transactions broken into local transactions
  • Compensating transactions for rollback
  • Event-driven coordination
  • Use cases: Microservices, long-running workflows

Event Sourcing

  • Store all changes as sequence of events
  • Current state derived by replaying events
  • Enables audit trails and temporal queries
  • Challenges: Event schema evolution, storage requirements

CQRS (Command Query Responsibility Segregation)

  • Separate read and write models
  • Write model: Command handlers, event stores
  • Read model: Optimized for specific query patterns
  • Benefits: Performance, scalability, flexibility

Outbox Pattern

  • Local transaction writes to outbox table
  • Background process publishes events
  • Ensures exactly-once delivery
  • Use cases: Event-driven architectures

Consistency and Consensus

Linearizability: The Strongest Consistency

Linearizability provides the strongest consistency guarantees:

Definition

  • Operations appear to happen atomically at some point in time
  • All nodes see operations in the same order
  • Real-time ordering preserved
  • Example: Distributed lock service

Implementation

  • Single-leader replication: All writes go through leader
  • Consensus algorithms: Raft, Paxos for ordering
  • Global timestamps: Lamport clocks or vector clocks
  • Synchronization: Coordinating across all nodes

Challenges

  • Performance impact: Operations must be ordered globally
  • Availability trade-off: CAP theorem implications
  • Network partitions: Linearizability impossible during partitions
  • Complexity: Hard to implement correctly

Use Cases

  • Distributed locks: Ensuring exclusive access
  • Leader election: Single coordinator
  • Unique constraints: Preventing duplicate keys
  • Financial systems: Ensuring transaction ordering

Eventual Consistency: Weaker but Available

Eventual consistency accepts temporary inconsistencies:

Definition

  • All replicas eventually converge to same state
  • Temporary inconsistencies acceptable
  • Better availability and performance
  • Example: DNS, CDN content

Trade-offs

  • Better availability: System continues during partitions
  • Higher performance: No global coordination required
  • Temporary inconsistencies: Application must handle them
  • Complex reasoning: Hard to reason about system state

Implementation Patterns

  • Vector clocks: Tracking causal relationships
  • Conflict resolution: Merging concurrent changes
  • Anti-entropy: Background synchronization
  • Read repair: Fixing inconsistencies during reads

Use Cases

  • Content delivery: CDNs, social media feeds
  • Offline applications: Mobile apps, desktop software
  • Real-time collaboration: Google Docs, Figma
  • IoT systems: Edge computing with eventual sync

Consensus Algorithms: Agreement in Distributed Systems

Consensus algorithms enable nodes to agree on values:

Paxos

  • Classic algorithm: Foundation for many systems
  • Complex to understand: Hard to implement correctly
  • Used by: Google’s Chubby, Apache ZooKeeper
  • Three roles: Proposers, acceptors, learners

Raft

  • Designed for understandability: Easier than Paxos
  • Leader-based: Single leader handles all requests
  • Log replication: Maintaining consistent logs
  • Used by: etcd, Consul, many distributed databases

Byzantine Fault Tolerance

  • Handles arbitrary failures: Malicious behavior
  • More expensive: Higher message complexity
  • Use cases: Blockchain, secure systems
  • Algorithms: PBFT, Tendermint

Consensus Properties

  • Safety: No two nodes decide different values
  • Liveness: Eventually some value is decided
  • Termination: All correct nodes eventually decide
  • Validity: Only proposed values can be decided

Stream Processing

Event Streams: The Foundation of Modern Systems

Event streams are becoming the backbone of data systems:

Event Sourcing

  • Complete history: All changes stored as events
  • Current state: Derived by replaying events
  • Audit trails: Compliance and debugging
  • Temporal queries: Understanding state at any point

Benefits

  • Debugging: Replay events to reproduce issues
  • Analytics: Analyze patterns over time
  • Compliance: Complete audit trail
  • Flexibility: Multiple read models from same events

Challenges

  • Storage: Events accumulate over time
  • Performance: Replaying long event histories
  • Schema evolution: Changing event structures
  • Complexity: More complex than traditional CRUD

Implementation

  • Event store: Append-only log of events
  • Aggregates: Domain objects with event sourcing
  • Snapshots: Periodic state checkpoints
  • Projections: Read models built from events

CQRS: Separating Read and Write Concerns

Command Query Responsibility Segregation separates different operations:

Command Side

  • Command handlers: Processing write operations
  • Event stores: Storing domain events
  • Aggregates: Enforcing business rules
  • Validation: Input validation and business logic

Query Side

  • Read models: Optimized for specific queries
  • Projections: Building read models from events
  • Caching: Storing frequently accessed data
  • Optimization: Denormalization for performance

Benefits

  • Performance: Optimize each side independently
  • Scalability: Scale read and write separately
  • Flexibility: Different storage for different needs
  • Maintainability: Clear separation of concerns

Challenges

  • Complexity: More complex than traditional CRUD
  • Eventual consistency: Read models may lag behind
  • Data synchronization: Keeping read models up to date
  • Learning curve: New patterns and concepts

Stream Processing Systems

Apache Kafka

  • Distributed commit log: High-throughput message broker
  • Fault tolerance: Replicated across multiple brokers
  • Use cases: Event streaming, message queues
  • Features: Exactly-once delivery, stream processing

Apache Flink

  • Stream processing: Real-time data processing
  • Exactly-once semantics: Ensuring data consistency
  • Stateful computations: Maintaining state across events
  • Use cases: Real-time analytics, fraud detection

Apache Spark Streaming

  • Micro-batch processing: Processing data in small batches
  • Integration: Works with batch processing
  • Use cases: Near real-time analytics
  • Features: Fault tolerance, scalability

Stream Processing Patterns

  • Windowing: Processing data in time windows
  • Joins: Combining multiple streams
  • Aggregations: Computing statistics over streams
  • Pattern matching: Detecting sequences of events

The Future of Data Systems

Unbundling the Database

  • Specialized systems: Different tools for different workloads
  • Polyglot persistence: Use the right tool for each job
  • Microservices: Each service with its own data store
  • Data mesh: Decentralized data ownership

Machine Learning Integration

  • ML models: Part of data pipelines
  • Real-time features: Computing features on streams
  • Automated decisions: ML-driven system behavior
  • Model serving: Deploying models in production

Privacy and Compliance

  • GDPR, CCPA: Data protection regulations
  • Data lineage: Tracking data origins and transformations
  • Governance: Data quality and access control
  • Differential privacy: Protecting individual privacy

Edge Computing

  • Local processing: Computing closer to data sources
  • Reduced latency: Faster response times
  • Bandwidth optimization: Processing data locally
  • Offline operation: Working without network connectivity

Emerging Technologies

NewSQL Databases

  • ACID transactions: Traditional database guarantees
  • Horizontal scaling: Distributed across multiple nodes
  • SQL compatibility: Familiar query language
  • Examples: CockroachDB, TiDB, YugabyteDB

Time-Series Databases

  • Optimized storage: Efficient for time-ordered data
  • Compression: Reducing storage requirements
  • Aggregation: Pre-computing common queries
  • Examples: InfluxDB, TimescaleDB, Prometheus

Graph Databases

  • Relationship modeling: Natural for complex relationships
  • Traversal queries: Finding paths between entities
  • Graph algorithms: PageRank, community detection
  • Examples: Neo4j, Amazon Neptune, ArangoDB

Vector Databases

  • Similarity search: Finding similar vectors
  • Embedding storage: Storing ML model embeddings
  • Semantic search: Finding conceptually similar items
  • Examples: Pinecone, Weaviate, Qdrant

Conclusion

Designing data-intensive applications requires understanding fundamental trade-offs between consistency, availability, and partition tolerance. Kleppmann’s book teaches us that there are no silver bullets—every design decision involves trade-offs that must be made based on specific requirements.

The key principles are:

  1. Start simple: Begin with the simplest solution that meets your needs
  2. Understand trade-offs: Every choice has consequences
  3. Plan for failure: Design for the failures you’ll encounter
  4. Monitor everything: Observability is crucial for production systems
  5. Evolve complexity: Add complexity only when necessary

Remember: Simplicity is the ultimate sophistication. The best data systems are those that solve real problems with the minimum necessary complexity, not those that showcase the most advanced techniques.

Whether you’re building a simple web application or a global distributed system, these principles provide the foundation for making informed architectural decisions. The goal is not to build the most complex system possible, but to build the simplest system that meets your requirements for reliability, scalability, and maintainability.


This blog post is inspired by Martin Kleppmann’s “Designing Data-Intensive Applications.” For a deeper dive into any of these concepts, I highly recommend reading the book itself—it’s an essential resource for anyone building systems that handle data at scale.

The book covers these topics in much greater detail, with real-world examples, implementation details, and practical advice for system designers and engineers.