Batching is the mechanism by which React groups multiple state updates into a single re-render. Before React 18, batching was limited to updates inside React event handlers. An update inside a setTimeout, a promise callback, or a native event listener triggered a separate render for each update. React 18 extended batching to all update sources,…
Concurrent rendering is not a feature that makes React faster. It is a scheduling model that changes when React does its work. The scheduler assigns a priority to every state update, processes the highest-priority work first, and yields to the browser between small slices of work so that user input is never blocked by a…
Strict Mode is a development-only wrapper that deliberately runs certain parts of React’s lifecycle more than once. It is not a bug, a performance problem, or something that happens in production. It is a diagnostic tool that surfaces code which violates React’s rules—impure renders, missing effect cleanups, and state that does not reset correctly. The…
React’s rendering pipeline is divided into two distinct phases with different rules, different guarantees, and different failure modes. The render phase is where React calls component functions, compares the new element tree to the previous one, and determines what needs to change. The commit phase is where React applies those changes to the DOM, runs…
React Fiber is not a feature that application developers interact with directly. It is the internal engine that determines how and when React renders. Before Fiber, React used a recursive reconciler that walked the component tree synchronously. Once rendering began, it could not be interrupted. A deeply nested component tree or an expensive render could…
A database driver is a translator. The application speaks in function calls and typed objects; the database speaks in a binary protocol over a socket. The wire protocol is the contract between them: a sequence of messages with defined framing, a startup handshake that negotiates capabilities and authenticates the user, and a query phase that…
Database benchmarking is the discipline of measuring a system’s performance under a workload that is defined, repeatable, and representative of the use case. The three tools that dominate the conversation serve different purposes. sysbench is a lightweight, multi-threaded benchmark tool for quick impressions of system performance, with built-in tests for CPU, memory, file I/O, and…
Database unit testing frameworks exist because the logic inside stored procedures, functions, and triggers is code, and code that is not tested accumulates defects silently. The challenge is that database code does not return values or throw exceptions in the way that application code does. A stored procedure communicates through result sets and output parameters….
Cross-database migration and schema evolution are two different problems that are often confused because both involve moving data and changing structure. A cross-database migration moves data from one database engine to another—PostgreSQL to SQL Server, MySQL to PostgreSQL, on-premises to cloud. Schema evolution changes the structure of a database while it is running, with the…
Database auditing is not a single mechanism but a spectrum of approaches that differ in what they capture, where the record is stored, and whether the record can be tampered with by the same principals being audited. The choice of approach is determined by the compliance framework and the threat model, not by convenience. A…