SGBDRs

SGBDRs, or Systèmes de Gestion de Bases de Données Relationnelles, are software systems that store and manage data according to the relational model. Data is organized into tables (relations) with rows (records) and columns (attributes). Relationships among data are represented through keys and constraints, and SQL is the primary language for defining, querying, and updating data.

Key characteristics include a schemas-based design, data integrity through constraints (primary keys, foreign keys, unique constraints), and ACID transactions that ensure atomicity, consistency, isolation, and durability. Normalization is commonly used to reduce redundancy, while indexes speed up data access.

Typical architecture comprises storage engines, a query processor with an optimizer, a transaction manager, and concurrency control mechanisms. Many SGBDRs support transactions across multiple statements and provide features such as durability logging, replication, backups, and disaster recovery.

History and standards: Relational databases were proposed by E. F. Codd in 1970. SQL emerged in the 1970s and 1980s and has since become the dominant standard, with variants from vendors such as MySQL, PostgreSQL, Oracle, SQL Server, and IBM Db2.

Use and considerations: SGBDRs are widely used for OLTP applications and transactional workloads requiring strong consistency. They contrast with NoSQL systems that prioritize schema flexibility or horizontal scalability. Trade-offs include schema rigidity and scaling challenges versus maturity, reliability, and strong transactional guarantees.