Memory structures consisting of essentially of two memory areas:
Memory area allocated to the SGA (System Global Area) : allocated to start the instance and represents a fundamental component of an Oracle instance. It consists of several memory areas:
The shared memory area
The buffer cache of the database
Buffer logging and other structures for the management of internal and external locks, statistical data, etc ...
The LARGE POOL memory area
The Java memory area
Memory allocated for the PGA (Program Global Area) is allocated at the start of the process server. It is reserved for each user process that connects to the Oracle database and is released at the end of the process.
The user process
The program which interacts with the database by starting a connection. It communicates only with the process server.
Represents the program that interact directly with the Oracle server. It responds to all requests and return results. It can be dedicated to a client or a server shared by many.
The Oracle database is a collection of data treated as a single entity and consists of three types of files including: