"深入理解Oracle系统管理与架构"

The system architecture of Oracle includes three main components: System Global Area (SGA), Process, and Files. When the Oracle system is started, it occupies a large amount of memory space on the host to control information and store data, known as SGA. The SGA is primarily composed of three main components: Shared Pool, Database Buffer Cache, and Redo Log Buffer. The Shared Pool is mainly composed of the Library Cache, Dictionary Cache, and some control structures, contributing to the efficient sharing of data and code across multiple users. The Database Buffer Cache stores data blocks that have been recently used, resulting in improved performance by reducing disk I/O. The Redo Log Buffer records all changes made to the database, providing a crucial component for recovery and backup operations. In addition to the SGA, the Oracle system architecture also includes the Process component, which is responsible for managing and executing user requests. Each user session is represented by a dedicated server process or a shared server process, allowing for efficient utilization of system resources. The Files component of the Oracle system architecture includes data files, control files, and redo log files. Data files contain the actual data and indexes of the database, while control files maintain the structural integrity of the database, recording the physical structure and status of the database. Redo log files store a record of all changes made to the database, providing a critical component for recovery in the event of a failure. Overall, the Oracle system architecture is designed to efficiently manage and store data, with the SGA providing a dedicated memory space for controlling and storing information, while the Process and Files components handle the execution of user requests and the management of database files. These components work together to ensure the reliability, performance, and security of the Oracle database system.