Key Technologies
The tools that power modern distributed systems. Know not just what they are, but when to use them, what problems they solve, and what their trade-offs are.
Redis
In-Memory Data Store
Primary choice for caching, session storage, pub/sub, and distributed locks. Supports rich data structures (sorted sets, streams) making it versatile beyond simple key-value.
Kafka
Distributed Event Streaming
Durable, high-throughput event bus. Enables decoupled async communication, event sourcing, and real-time stream processing. Consumers can replay events from any offset.
Elasticsearch
Distributed Search & Analytics
Full-text search, fuzzy matching, geo-search, and log analytics at scale. Uses inverted indexes. Common for search-as-a-service alongside a primary DB.
Cassandra
Wide-Column NoSQL DB
Optimized for high write throughput, linear scalability, and multi-region deployments. Tunable consistency. Ideal for time-series data, activity logs, and messaging.
DynamoDB
Managed NoSQL (AWS)
Serverless key-value / document store with single-digit millisecond latency at any scale. Ideal for predictable access patterns. Global tables for multi-region.
PostgreSQL
Relational Database
Battle-tested RDBMS with strong ACID guarantees. Supports JSONB, full-text search, and PostGIS for geo. Default choice when you need strong consistency and complex queries.
Flink
Stream & Batch Processing
Stateful stream processing with exactly-once semantics. Used for real-time aggregations, event-time windowing, and complex event processing on Kafka streams.
ZooKeeper
Distributed Coordination
Leader election, distributed configuration, service discovery, and distributed locks. Acts as the source of truth for cluster coordination in systems like Kafka, HBase.
API Gateway
Edge Routing Layer
Single entry point for all clients. Handles routing, auth, rate limiting, SSL termination, and request transformation. Decouples clients from microservice topology changes.