Mock Service Worker is not a Jest mock. It is a network-level interceptor. When your React component calls fetch(‘/api/users’), MSW intercepts that request before it leaves the process, matches it against the handlers you defined, and returns the mocked response as if it came from a real server . The component’s actual fetch call runs,…
Spatial data represents information about the physical location and shape of geometric objects—points, lines, polygons, and the relationships between them . A database that can store coordinates is not automatically a spatial database. A spatial database must understand the geometry’s structure, support the operations that answer spatial questions (does this point fall inside that polygon?…
A B-tree index answers one question well: does this value fall within this ordered range? It is the correct index for equality and range predicates on scalar columns, and it is the default because most queries ask exactly that question. But a query that asks “which documents contain the word ‘index’” or “which geometric shapes…
The query execution engine is the component that takes the physical plan chosen by the optimizer and actually runs it. The optimizer decides what to do—which join algorithm, which index, which order. The execution engine decides how fast to do it. Two execution models dominate the landscape: the Volcano iterator model and vectorized execution. The…
A join is the operation that combines rows from two tables based on a condition. The SQL statement says what to join; the optimizer chooses how to join it. That choice is one of three physical algorithms: nested loop, hash join, or merge join. Each has a different cost profile, a different set of conditions…
The cost-based optimizer is the component of a database that decides how to execute a query. It does not guess. It reads statistics about the tables, columns, and indexes involved, estimates how many rows each step of the plan will produce, and assigns a cost to every candidate plan. The plan with the lowest cost…
Intro The Core Web Stack path covers the essential foundation required to design, build, and deploy modern web applications. From understanding basic web protocols and standard client-side markup to building REST APIs, managing source code with version control, and handling package dependencies, this roadmap provides a complete developer toolkit. Tutorials
Every package you install with npm lands in one of two places in your package.json: dependencies or devDependencies. The distinction is not cosmetic. It determines whether the package is installed when you build for production, whether it is shipped in your deployment artifact, and whether your production server can actually run the code after deployment….
The package.json file is the single most important file in a Node.js project. It is the manifest that tells npm what the project is, what it depends on, and how to run it. Every npm install, npm run, and npm publish reads this file. The npm documentation describes it as “the whole interface” to npm—without…
Every Node.js project begins with a package.json file. It is the manifest that records the project’s name, its version, its scripts, and the dependencies it needs. Creating that file by hand is possible but error-prone: a missing name, a version that does not follow semantic versioning, or a typo in the scripts key produces a…