Daily Archives: October 19, 2024

The Program Global Area (PGA) is an essential memory structure in Oracle databases, specifically allocated for a dedicated server session. It is subdivided into various areas, each serving distinct purposes. Here’s an overview of the key contents of the PGA:

The Fixed SGA (System Global Area) is a predefined memory area within the Oracle database that serves essential housekeeping functions

The Streams pool is a dedicated memory area used exclusively by Oracle Streams to manage data replication and messaging

The Java pool is a dedicated area of memory within the Oracle database that stores session-specific Java code and data executed in the Java Virtual Machine (JVM).

The large pool is an optional memory area in Oracle databases designed for memory allocations that exceed the size limits of the shared pool.

The shared pool stores parsed SQL statements, PL/SQL code, system parameters, and data dictionary information. It plays a role in nearly every database operation, such as executing SQL statements.

The redo log buffer is a circular buffer located in the System Global Area (SGA) that stores redo entries, which describe changes made to the database.

The database buffer cache, or simply the buffer cache, is a critical memory area that stores copies of data blocks read from data files. It allows all users connected to a database instance to share access to these cached data blocks.