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A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
SELECT FOR UPDATE
A locking read that acquires exclusive row locks — preventing other transactions from modifying selected rows until commit.
1mo ago database advanced
Soft Delete Pattern
Marking records as deleted with a deleted_at timestamp instead of physically removing them — preserving data for auditing and recovery.
1mo ago database intermediate
SQL Window Functions
Window functions (ROW_NUMBER, RANK, LAG, LEAD, SUM OVER) perform calculations across a set of rows related to the current row without collapsing them into a single aggregate — enabling rankings, running totals, and comparisons within result sets.
1mo ago database intermediate
Change Data Capture (CDC)
A pattern for tracking and streaming every insert, update, and delete from a database — by reading the database's internal transaction log rather than polling tables — enabling real-time event-driven integrations without impacting query performance.
2mo ago database advanced
Database Indexes
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.
2mo ago database intermediate
OLAP vs OLTP
OLTP (Online Transaction Processing) optimises for many small, fast read/write operations — your main application database. OLAP (Online Analytical Processing) optimises for few, large analytical queries scanning millions of rows — your reporting and analytics database.
2mo ago database intermediate
ORM — Object-Relational Mapper PHP 7.0+
A library that maps database rows to PHP objects and vice versa — handling SQL generation, relationships, and lazy loading, at the cost of hiding query behaviour that can cause N+1 problems if used carelessly.
2mo ago database beginner
Query Optimisation
The process of rewriting SQL queries and database structures to reduce execution time — using EXPLAIN to identify full table scans, adding targeted indexes, rewriting JOINs, and eliminating N+1 patterns.
2mo ago database intermediate
SQLite in Production PHP 5.1+
SQLite is a serverless, file-based SQL database that is appropriate for production use in single-server applications, edge deployments, and embedded systems — with specific limitations around concurrent writes that make it unsuitable for multi-server setups.
2mo ago database intermediate
Write-Ahead Log (WAL)
A durability technique where changes are written to an append-only log before being applied to the database — if the system crashes, the log is replayed to restore the database to a consistent state.
2mo ago database advanced
Column-Level Encryption PHP 7.1+
Encrypting sensitive database columns (SSN, credit card, medical data) — application holds the key; database never sees plaintext; breach exposes only ciphertext.
2mo ago database advanced
Diagram: Database Replication Database Replication PHP 5.0+
Copying data from one database server to replicas — synchronous replication guarantees zero data loss, asynchronous is faster but risks losing recent writes on failure.
2mo ago database intermediate
Diagram: Database Triggers 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.
2mo ago database intermediate
Document Stores PHP 7.0+
Databases that store semi-structured documents (JSON/BSON) — MongoDB, CouchDB — flexible schema, nested data, and horizontal scaling at the cost of no joins and eventual consistency.
2mo ago database intermediate
DSN Security & Connection String Secrets PHP 5.0+
Database credentials in connection strings must never be hardcoded — use environment variables or secrets managers, least-privilege users, and never log DSNs.
2mo ago database intermediate
Diagram: Eventual Consistency in Databases Eventual Consistency in Databases
A consistency model where replicas are not immediately synchronised — all nodes will converge to the same state given no new writes, trading consistency for availability and partition tolerance.
2mo ago database advanced
Graph Databases
Databases where relationships are first-class citizens — Neo4j, Amazon Neptune — optimised for traversing complex networks of connected entities that are expensive in relational databases.
2mo ago database advanced
Diagram: PostgreSQL VACUUM & ANALYZE PostgreSQL VACUUM & ANALYZE PHP 5.0+
VACUUM reclaims storage from dead tuples created by MVCC updates and deletes. ANALYZE updates query planner statistics. Both are essential for PostgreSQL performance.
2mo ago database advanced
Time-Series Databases PHP 5.0+
Databases optimised for storing and querying time-stamped data — metrics, events, sensor readings — with efficient range queries, downsampling, and data retention policies.
2mo ago database intermediate
Diagram: Common Table Expressions (CTEs) Common Table Expressions (CTEs) PHP 5.0+
Named temporary result sets defined with the WITH clause that can be referenced in a query, improving readability and enabling recursive queries.
2mo ago database intermediate
✓ schema.org compliant