Specifying the DDL Lock Timeout
- Nonblocking DDL waits until every concurrent DML transaction that references the object affected by the DDL either commits or rolls back.
- Blocking DDL fails, though it might have succeeded if it had been executed subseconds later when the locks become available.
Specifying the Maximum Number of Processes
Specifying a Fast Recovery Area
- DB_RECOVERY_FILE_DEST: Location of the Fast Recovery Area. This can be a directory, file system, or Automatic Storage Management (Oracle ASM) disk group. It cannot be a raw file system.
- In an Oracle Real Application Clusters (Oracle RAC) environment, this location must be on a cluster file system, Oracle ASM disk group, or a shared directory configured through NFS.
- DB_RECOVERY_FILE_DEST_SIZE: Specifies the maximum total bytes to be used by the Fast Recovery Area. This initialization parameter must be specified before DB_RECOVERY_FILE_DEST is enabled.
Nonstandard Block Sizes
- The SGA is a group of shared memory structures, known as SGA components, that contain data and control information for one Oracle Database instance. The SGA is shared by all server and background processes. Examples of data stored in the SGA include cached data blocks and shared SQL areas.
- A PGA is a memory region that contains data and control information for a server process. It is nonshared memory created by Oracle Database when a server process is started. Access to the PGA is exclusive to the server process. There is one PGA for each server process. Background processes also allocate their own PGAs. The total PGA memory allocated for all background and server processes attached to an Oracle Database instance is referred to as the total instance PGA memory, and the collection of all individual PGAs is referred to as the total instance PGA, or just instance PGA.
Automatic Memory Management
Memory Management Data Dictionary Views
Displays summary information about the system global area (SGA).
Displays size information about the SGA, including the sizes of different SGA components, the granule size, and free memory.
Displays detailed information about how memory is allocated within the shared pool, large pool, Java pool, and Streams pool.
Displays PGA memory usage statistics as well as statistics about the automatic PGA memory manager when it is enabled (that is, when PGA_AGGREGATE_TARGET is set). Cumulative values in V$PGASTAT are accumulated since instance startup.
Displays information on the current size of all automatically tuned and static memory components, with the last operation (for example, grow or shrink) that occurred on each.
Displays the current sizes of all SGA components, and the last operation for each component.
Displays information about the amount of SGA memory available for future dynamic SGA resize operations.
Displays information about resize operations that are currently in progress. A resize operation is an enlargement or reduction of the SGA, the instance PGA, or a dynamic SGA component.
Displays information about dynamic SGA component resize operations that are currently in progress.
Displays information about the last 800 completed memory component resize operations, including automatic grow and shrink operations for SGA_TARGET and PGA_AGGREGATE_TARGET.
Displays information about the last 800 completed SGA component resize operations.
Displays information that helps you tune MEMORY_TARGET if you enabled automatic memory management.
Displays information that helps you tune SGA_TARGET.
Displays information that helps you tune PGA_AGGREGATE_TARGET.