Terms starting with "D"
Data Clump
The same group of variables appearing together repeatedly — a signal they belong in a class together.
6mo ago
Code Quality intermediate
Data Mapper vs Active Record
1
Two ORM patterns: Active Record bakes persistence into the domain object itself; Data Mapper separates the domain object from its persistence mechanism.
6mo ago
Architecture advanced
Data Transfer Object (DTO)
PHP 8.0+
A simple object that carries data between layers or systems with no business logic — reducing coupling between layers and making data contracts explicit.
6mo ago
Code Quality intermediate
Database Connection Pool Sizing
PHP 5.0+
2
The optimal pool size is smaller than you think — follow the formula (cores × 2) + effective_spindle_count rather than matching thread count.
6mo ago
Performance advanced
Database Deadlocks
PHP 5.0+
4
A situation where two or more transactions hold locks the other needs, each waiting indefinitely — resolved by the database killing one transaction.
6mo ago
Database advanced
Database Indexes — Types & Trade-offs
PHP 5.0+ B-Tree, hash, full-text, and partial indexes — each suited to different query patterns, with write overhead as the cost of read speed.
6mo ago
Database intermediate
Database Indexing
PHP 5.0+
3
Indexes are data structures that allow the database to find rows matching a WHERE clause without scanning the entire table.
6mo ago
Performance intermediate
Database Migrations
PHP 5.0+
1
Version-controlled, incremental scripts that evolve the database schema alongside code, enabling reproducible deployments and rollbacks.
6mo ago
General intermediate
Database Normalisation
PHP 5.0+
Organising relational database tables to reduce redundancy and improve integrity — from 1NF through 3NF (and beyond) as design guidelines.
6mo ago
General intermediate
Database Normalisation
1
The process of structuring a relational database to reduce redundancy and improve integrity, defined through progressive normal forms (1NF through BCNF).
6mo ago
Database intermediate
Database Partitioning
PHP 5.0+
1
Splitting a large table into physical segments by range, list, or hash — enabling partition pruning, faster archival, and parallel scans.
6mo ago
Performance advanced
Database Schema Design
PHP 5.0+
5
The process of defining tables, columns, data types, constraints, and relationships — decisions made at schema design time are expensive to reverse once data is live.
6mo ago
Database intermediate
Database Sharding
PHP 5.0+ Horizontally partitioning data across multiple database instances by a shard key, scaling write throughput beyond a single server's limits.
6mo ago
Performance advanced
Database Transactions
PHP 5.1+
4
A sequence of SQL operations treated as a single atomic unit — all succeed or all roll back — enforcing ACID guarantees.
6mo ago
Database intermediate
Database Views & Materialised Views
PHP 5.0+
1
A view is a saved SELECT query presented as a virtual table. A materialised view stores the query result physically — trading freshness for query speed.
6mo ago
Database intermediate
Date / Time Functions
PHP 5.5+
1
PHP's date/time API including DateTime, DateTimeImmutable, and DateTimeZone for safe, timezone-aware date handling.
6mo ago
PHP beginner
DDD Aggregates & Aggregate Roots
2
A cluster of domain objects treated as a single unit with one root entity controlling access and enforcing invariants across the cluster.
6mo ago
Architecture advanced
DDD Domain Services
Domain logic that doesn't naturally belong to any single entity or value object — cross-entity operations modelled as stateless service classes.
6mo ago
Architecture advanced
DDD Repositories vs Active Record
Repository pattern separates persistence from domain logic — the opposite of Active Record where the model knows how to save itself.
6mo ago
Architecture advanced
DDD Value Objects in PHP
Immutable objects defined by their attributes rather than identity — Money, Email, Coordinate — that encapsulate validation and domain behaviour.
6mo ago
Architecture intermediate