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Lessons (40)
- Database Internals, Replication and Scaling
Connect storage-engine choices, durability, replicas, query plans, pooling and data layout to real production behaviour. ![Database path …
- Storage Engines & Database Operations
Understand B-trees, LSM trees, write-ahead logs, connection pools, backups and the signals behind database reliability. What …
- Database Relations & Foreign Keys
… It is a database promise: an order belongs to one customer; an order contains many items; a student …
- SQL vs NoSQL Databases
… scale OUT"] H1[Node 1] H2[Node 2] H3[Node 3] H4["+ Node 4"] end NoSQL databases like …
- Transactions, Indexes & Concurrency
… state the database product you mean. Q11: Livelock versus deadlock Deadlock is circular waiting, so the database aborts …
- Database Indexing & Transactions
… A database index works the same way. , Kafka can …
- Caching, Consistent Hashing and Sharding
Move reads close to users, distribute data safely, and understand cache and database consistency costs. Three different tools …
- ACID, Transactions & Locks
… Let the database make the decision atomically: UPDATE inventory SET available = available - 1 WHERE sku = :sku AND available …
- Clean Architecture
Organise an application in layers so business rules don't depend on frameworks, databases or the web. Follow …
- Caching & Redis
… database and stores the result. mermaid sequenceDiagram participant App participant Cache as Redis participant DB as Database App …
- Onion Architecture & Clean vs Hexagonal vs Onion
… Infrastructure (databases, UI, frameworks) is the outer skin . , and state in the database. Scaling …
- Replication, Partitioning & Sharding
… independent database owners A shard key routes each row to one shard: tenant id is often safer than …
- Hexagonal Architecture (Ports & Adapters)
… the database is at the bottom"] direction TB L1[UI] -- L2[Business] -- L3[(Database)] end subgraph Hex["Hexagonal …
- ConfigMaps, Secrets & Storage
… Opaque stringData: plain text here; stored base64-encoded DATABASE URL: "postgres://shop:s3cr3t@postgres:5432/shop" STRIPE API …
- Design a URL Shortener
… design-l6/url-shortener.svg) Generate a Base62 database ID or collision-checked random code. Store code, destination …
- Clean Architecture in Depth
… Web frameworks, databases, UIs and third-party APIs are the cabins and paint: details that plug in from …
- Design an E-Commerce Checkout
… Do not hold a database transaction open across payment. Handle unknown provider outcomes through reconciliation; expire reservations; isolate …
- Deployments, ReplicaSets & Rollouts
… APIs, web frontends Interchangeable pods, rolling updates StatefulSet Databases, Kafka, ZooKeeper, Elasticsearch Stable names ( db-0 , db-1 …
- Docker & Containers
… docker run -d -p 3000:3000 --name api -e DATABASE URL=postgres://… shop-api:1.0 docker logs …
- Time, Consistency and Distributed Transactions
… Avoid distributed locks where atomic database/queue claiming owns the state. Two-phase commit offers coordinated atomicity but …
- SQL Interview Query Drills
… define grouping, compute an aggregate, then filter with a clear tie policy](/img/database-interviews/sql-drills.svg …
- What Is Software Architecture?
… Monolith or microservices, layers, sync vs async, which database, where the business logic lives 🔴 High Design How is …
- Creational Patterns: How to Make Objects
… a database pool, a config object, a logger. js // db.js — ES modules are evaluated ONCE and cached …
- Normalization & Denormalization
… one fact, one home Normalization organizes a relational database so a fact is stored once, in the table …
- Debug Latency Like an Investigator
… CPU can be low throughout.  Q2, Q3 and …