Intermediate terms
Dependency Injection in Python
Python 3.8+
A design technique where objects receive their collaborators from outside rather than constructing them internally, inverting who controls instantiation.
3mo ago
Python intermediate
Database Bulk Operations
PHP 7.0+
3
Process many rows in a single SQL statement or batched transaction instead of one round-trip per row, for far higher throughput.
3mo ago
Database intermediate
Database Query Result Streaming
PHP 8.0+
2
Processing large result sets row-by-row without loading the entire dataset into memory - essential for PHP CLI scripts handling millions of rows.
5mo ago
Database intermediate
Discriminated Unions
2.0
2
A union of types that each carry a shared literal field (the discriminant) allowing TypeScript to narrow exhaustively — the canonical way to model mutually exclusive states.
6mo ago
TypeScript intermediate
Dependency & Supply Chain Security
Protecting applications from malicious or vulnerable third-party packages — covering transitive dependencies, lock files, SRI hashes, CVE scanning, and supply chain attack vectors.
CWE-1357 OWASP A6:2021
6mo ago
Security intermediate
Docker HEALTHCHECK
4
A Dockerfile instruction that defines how Docker tests whether a container is healthy — enabling automatic restart and load balancer removal on failure.
6mo ago
DevOps intermediate
Dead Code Elimination
PHP 7.4+
3
A compiler and static analysis optimisation that identifies and removes code that can never be executed or whose result is never used.
6mo ago
Compiler intermediate
Database Connection Pooling
2
Connection pooling reuses a fixed set of database connections across requests — eliminating the 50–200ms connection overhead on every request and limiting DB connection count.
6mo ago
Concurrency intermediate
Database Indexes
4
Data structures that allow the database engine to find rows matching a condition without scanning every row — the single most impactful performance optimisation available for read-heavy PHP applications.
6mo ago
Database intermediate
Dead Letter Queue
1
A Dead Letter Queue (DLQ) captures messages that can't be processed — expired, malformed, or repeatedly failed — enabling later inspection and replay without losing data.
6mo ago
Messaging intermediate
Deadlock
3
A deadlock occurs when two or more processes each hold a resource the other needs — both wait forever. Prevention requires consistent lock ordering or timeouts.
6mo ago
Concurrency intermediate
DI Containers — PHP-DI, Symfony & Laravel Compared
PHP 7.4+
4
A Dependency Injection container automates wiring of class dependencies — instead of manually constructing objects and their dependencies, the container reads type hints and builds the full object graph. PHP-DI, Symfony's DIC, and Laravel's service container are the main options.
6mo ago
PHP intermediate
Distributed Tracing
3
Distributed tracing tracks a request as it flows through multiple services — each service adds a span to a shared trace, giving end-to-end visibility into latency and failures.
6mo ago
Observability intermediate
DOMDocument & XPath in PHP
PHP 5.0+
1
PHP's DOMDocument extension parses HTML and XML into a traversable tree. Combined with DOMXPath, you can query the document with XPath expressions — far more powerful than regex for extracting data from HTML.
6mo ago
PHP intermediate
Deprecation Notices & Migration Strategy
PHP 5.0+
1
E_DEPRECATED warnings signal features removed in the next PHP major version — treating them as errors in CI prevents upgrade blockers from accumulating.
6mo ago
PHP intermediate
Database Replication
PHP 5.0+
2
Copying data from one database server to replicas — synchronous replication guarantees zero data loss, asynchronous is faster but risks losing recent writes on failure.
6mo ago
Database intermediate
Database Seeding & Fixture Management
PHP 5.0+
1
Populating databases with consistent, reproducible test and development data — using factories, seeders, and fixtures to create realistic scenarios without manual data entry.
6mo ago
General intermediate
Database Triggers
PHP 5.0+ Stored procedures that fire automatically on INSERT, UPDATE, or DELETE — useful for audit logs and enforcing constraints, but dangerous when they become hidden business logic.
6mo ago
Database intermediate
Dead Condition
PHP 5.0+
A boolean condition that is always true or always false due to logic errors, making the branch either always execute or never execute.
6mo ago
Code Quality intermediate
Dependency Audit & CVE Scanning
PHP 5.0+
1
Automated scanning of project dependencies for known vulnerabilities (CVEs) — composer audit, npm audit, and tools like Snyk run in CI to catch vulnerable packages before deployment.
6mo ago
General intermediate