Oracle Architecture Diagram

1 Oracle database mainly consists of data file database and DB instance instance. Users are linked to the server process through user processes. When the database is started, you need to rely on the parameter files parameter file, if our database is an archive mode, the Oracle database will write redo log files to archived log files, to avoid redo log files being overwritten
2 instance Introduction
When the database starts, it reads the parameter file SPFile and assigns a system globle area (SGA) based on the parameter file, the memory shared by each Oracle data session connection, and the shared pool for the SGA, which can be divided into a sharer pool. Store some data dictionary caches and common libraries of functions. For SGA, it is more important to have database buffer Cache,redo log buffer, Java pool, large pool, etc.
For the PGA and SGA allocations: PGA: Whenever a TCP connection is connected to Oracle, a session is generated and a PGA is assigned. For SGA: The memory that is shared by all sessions session, when the Oracle database is started it is initialized to allocate a shared memory area, the size of this SGA will not change after startup
2 database file: Data Files,control Files,redo Log files. Data files are mainly used for storing business data files, for control files are stored in a controlled file, Redo log files are stored in the database operation records, if the database is abnormally closed, the startup will read Redo log Files to repair the database
3 The database and instance of Oracle databases are communicated through a series of background. Different operations have different background processes to process

Oracle Architecture Diagram