What are the various Oracle Database memory components?

What are the various Oracle Database memory components?

The basic memory structures associated with Oracle include:

• Software Code Areas.
• System Global Area (SGA): the database buffer cache. the redo log buffer. the shared pool.
• Program Global Areas (PGA): the stack areas. the data areas.
• Sort Areas.

What are the three major structures in Oracle Database server architecture?

There are three major structures in Oracle Database server architecture: memory structures, process structures, and storage structures. A basic Oracle database system consists of an Oracle database and a database instance. The database consists of both physical structures and logical structures.

What is SGA PGA and UGA in Oracle?

The SGA is a group of shared memory structures, known as SGA components, that contain data and control information for one Oracle Database instance. Database initialization parameters set the size of the instance PGA, not individual PGAs. User Global Area (UGA) The UGA is memory associated with a user session.

Which data structure is the part of the shared global area SGA in Oracle Database architecture?

The database buffer cache is the portion of the SGA that holds copies of data blocks read from datafiles. All user processes concurrently connected to the instance share access to the database buffer cache. The database buffer cache and the shared SQL cache are logically segmented into multiple sets.

What is the difference between PGA and UGA?

The UGA normally comes from the SGA to allow migration of sessions across processes. If session migration is disabled, UGA memory will be allocated from the PGA. The Process Global Area (PGA) is memory which is physically private to a process (cannot be accessed by another process).

What does shared global area mean in Oracle?

A system global area(SGA) is a group of shared memory structures that contain data and control information for one Oracle database instance. If multiple users are concurrently connected to the same instance, then the data in the instance’s SGA is shared among the users. Consequently, the SGA is sometimes called the shared global area.

Which is a shared memory structure in Oracle?

System Global Area (SGA) A system global area (SGA) is a group of shared memory structures that contain data and control information for one Oracle database instance. If multiple users are concurrently connected to the same instance, the data in the instance’s SGA is “shared” among the users.

What kind of information is stored in Oracle?

Oracle uses memory to store information such as the following: Information about a connected session, even if it is not currently active Information needed during program execution (for example, the current state of a query from which rows are being fetched)

What kind of information is stored in the SGA?

Part of the SGA contains general information about the state of the database and the instance, which the background processes need to access; this is called the fixed SGA. No user data is stored here. The SGA also includes information communicated between processes, such as locking information.