Mathias Paulenko

How to create, analyze, and maintain indexes to speed up database queries and avoid common indexing mistakes.

How to identify, analyze, and fix slow SQL queries using EXPLAIN, query refactoring, and database-specific optimization techniques.

Improve Core Web Vitals, reduce bundle sizes, and optimize frontend performance with lazy loading, code splitting, and modern build tools.

How to capture all changes as immutable events using event sourcing with AWS Lambda, DynamoDB streams, and event stores for audit trails...

Create and deploy serverless functions with AWS Lambda, Google Cloud Functions, and Azure Functions for event-driven, pay-per-use compute.

How to coordinate complex serverless processes using AWS Step Functions, Temporal, and Durable Functions to manage state, retries, and...

How to generate realistic, deterministic test data with Faker, factory-boy, and type-aware generators for reliable test suites in Python,...

How to use mutation testing with MutPy, Stryker, and PIT to evaluate whether your tests actually assert behavior or merely execute code.

How to write property-based tests with Hypothesis, fast-check, and jqwik that generate thousands of inputs to find edge cases traditional...

How to use AssertJ soft assertions in JUnit5 to collect multiple assertion failures in a single test instead of stopping at the first...

How to use WireMock in Java tests to stub external HTTP services, including response templating, delay simulation, and stateful mock...

How to use Vitest snapshot testing to catch unintended UI changes in React components, including inline snapshots and snapshot updating...

How to simulate realistic traffic, measure response times, and identify bottlenecks using k6 and JMeter for APIs and web services.

How to measure, report, and enforce code coverage with branch and condition coverage using pytest-cov, nyc, and JaCoCo for meaningful...

How to measure and enforce Python test coverage thresholds with pytest-cov, including branch coverage, HTML reports, exclusions, and CI...

Stream data lazily with async generators. Yield values one at a time as they become available, enabling memory-efficient processing of...

Use the Decorator pattern to compose cross-cutting concerns like logging, metrics, and retries into HTTP request pipelines without...

Build a language interpreter that evaluates expressions and rules by representing grammar as composable objects, useful for formulas,...

Prevent duplicate processing by tracking message IDs with idempotency keys. Consumers check a store before processing to skip messages...

Smooth traffic spikes by placing a queue between a producer and a consumer. The producer writes messages at any rate; the consumer...

Preserve message ordering for related messages in a distributed system by grouping them into ordered sequences and processing them one at a...

Deploy static files to a dedicated content delivery network or object storage to offload origin servers, reduce latency, and improve...

How to define, schedule, and monitor Directed Acyclic Graphs in Apache Airflow with operators, sensors, XCom, and task dependencies.

How to use Dask for parallel DataFrame operations on datasets larger than memory, covering lazy evaluation, partitions, custom...