Relaatiotietokantainhallintajärjestelmä

Relaatiotietokantainhallintajärjestelmä (RDBMS) is a software system that manages relational databases, where data is organized in tables with rows and columns. The core concept of relational databases is based on E.F. Codd’s relational model, introduced in 1970. An RDBMS stores data on disk, provides a query language—typically SQL—supports transactions, data integrity constraints, and concurrency control.

Key components of an RDBMS include the storage engine, SQL parser and executor, transaction manager, and the buffer cache. The storage engine can vary (e.g., InnoDB for MySQL, BTREE for many systems), and it handles data layout and indexing. The transaction manager implements ACID properties—Atomicity, Consistency, Isolation, Durability—through mechanisms such as write-ahead logging and lock scheduling.

Typical features offered by modern RDBMSs are user authentication, role-based access control, stored procedures, triggers, views, and support for foreign keys and referential integrity. Performance tuning involves indexing strategies, query optimization, partitioning, and replication.

Common commercial and open-source RDBMSs include Oracle Database, Microsoft SQL Server, IBM Db2, PostgreSQL, MySQL, MariaDB, SQLite, and variables of the MariaDB family. While relational databases excel at handling structured data with well-defined schemas and complex joins, they can become less efficient for highly distributed, horizontally scalable workloads; in those cases NoSQL solutions may be preferred.

Standards such as the SQL standard (ANSI/ISO) guide interoperability between systems, though implementations can differ in proprietary extensions. The RDBMS remains fundamental in enterprise applications, financial systems, web services, and embedded devices due to its maturity, reliability, and robust querying capabilities.