Backend

Backend is the area I've been doing longest. These notes focus on the engines most of my systems actually run on — Postgres, Redis, Kafka, ClickHouse — with the fundamental properties (ACID, replication, storage internals) sitting alongside. Not a tutorial area: most notes are term-style entries to re-read when I need to remember how a specific piece works.

Architecture patterns

• CQRS — split command and query models when reads and writes diverge.
• Separation of concerns — boundaries between layers and reasons to change.

Node / API layer

• NestJS — structured Node framework (modules, DI, decorators).

Persistence and validation

• Prisma and Sequelize — ORMs on top of SQL stores.
• Zod — runtime validation at API edges.

Core properties

• ACID — atomicity, consistency, isolation, durability.
• Columnar storage — the storage model behind analytics engines.
• Algorithms MOC — the CS fundamentals layer under all of this.

Postgres

• Indexes, JSON
• Query planner
• Transactions, WAL, vacuum
• Replication, connection pooling, extensions

Redis

• Redis — overview and links into the note cluster.
• Data types
• Caching, expiration, memory management
• Persistence, clustering
• Pub/sub, streams, transactions, Lua scripts

Kafka

• Brokers, topics, partitions
• Producers, consumers, consumer groups, offsets
• Replication, Kafka Connect, Kafka Streams

ClickHouse

• MergeTree — the core storage engine.
• Primary index, partitioning, TTL
• Materialized views, query optimization
• Compression, replication, distributed tables

Tooling

• npm package template — my CLI for bootstrapping publishable npm packages.
• npm, pnpm, and Yarn — package managers for Node libraries and services.