# Data structures

An index can turn a slow query into a fast one, or slow down every insert on the table. In this article, we explain database indexing in SQL Server, PostgreSQL, and MySQL: eleven index types, when to use each one, when to avoid them, and how to find missing and unused indexes.

Prepare for your next .NET interview with 800+ interview questions and answers covering C#, ASP.NET Core, SQL, NoSQL, microservices, distributed systems, testing, AI, Agile, desktop and mobile development. For developers, senior engineers, architects and tech leads.

In this article, we review AI, LLM, prompting, .NET AI integration, Semantic Kernel, Microsoft Agent Framework, MCP, RAG, resilience, testing, observability, security, and AI coding tools for .NET engineers.

Learn how modern LLMs are trained, from pretraining and instruction tuning to SFT, RLHF, DPO, and model distillation. This guide explains how raw foundation models become production-ready AI assistants, coding copilots, and enterprise agents.

In this article, we explain what a Large Language Model is, how LLMs work, what they excel at, where they fall short, and how they fit into real software products.

This week: a comprehensive .NET desktop development interview guide covering WinUI 3, MAUI, and Avalonia. Lyft goes beyond A/B testing, using surrogates and region splits to measure long-term marketplace effects. Airbnb shares how COVID broke their forecasting models and the Bayesian architecture they built to survive the next shock. And Meta reveals the ML behind Friend Bubbles, blending social closeness models with content signals to power social discovery on Facebook Reels.

This part of C# / .NET interview questions and answers covering modern desktop development: WinUI 3, .NET MAUI, Avalonia UI, MVVM architecture with CommunityToolkit, performance optimization, data storage with EF Core and SQLite, secure credentials, background sync, MSIX packaging, and auto-update strategies. 

This week: Uber shows how AI agents can automate design system documentation via MCP and how real-time batching solves hot-key payment bottlenecks at scale. Airbnb shares a transformer-based model for recommending travel destinations to exploratory users. And Pinterest details how unified context-intent embeddings power their Analytics Agent — now the most widely adopted internal agent at the company.

60+ C# / .NET testing interview questions with code examples. Covers unit testing, integration testing, gRPC, contracts, distributed systems, Playwright, and performance.

In this article, we explore microservices and distributed systems interview questions and answers, and what every .NET engineer should know, from service boundaries and BFF to sagas, events, service discovery, and communication patterns.

Weekend Reading: A weekly roundup of interesting Software Architecture and Programming articles from tech companies. Find fresh ideas and insights every weekend.

This chapter explores NoSQL Databases questions that  .NET engineers should be able to answer in an interview.

This week, we look at consistency models in distributed systems, Uber’s adaptive benchmarking framework, LinkedIn’s evolution of its Venice ingestion pipeline, and Meta’s new open-source platform for adaptive experimentation.

Weekly tech digest: CAP theorem basics, Uber’s probabilistic heatmaps, Dropbox’s context-aware AI, and Lyft’s modern ML platform architecture.

In this article, we explore practical patterns for data versioning and schema evolution in NoSQL systems.

This week, we dive into SQL performance tips, Uber’s approach to fault-tolerant analytics, and how TikTok cut AI costs in half with smart caching.

Practical MongoDB best practices guide for developers. Covers schema design, indexing, performance, queries, transactions, sharding, and common mistakes with examples and links to official docs.

Practical SQL best practices for developers and DBAs. Learn how to design clean schemas, write readable and efficient queries, avoid common mistakes, and keep your database secure and fast

This chapter explores SQL Database questions that  .NET engineers should be able to answer in an interview.

Weekly tech digest: pagination strategies for large datasets, Uber’s rebuilt Apache Pinot query architecture, and Meta’s ML-based notification ranking system for Instagram.