tailieunhanh - 8 Monitoring and Managing Memory

After completing this lesson, you should be able to: • Describe the memory components in the SGA • Implement Automatic Shared Memory Management • Manually configure SGA parameters • Configure automatic PGA memory management | Monitoring and Managing Memory Objectives After completing this lesson, you should be able to: Describe the memory components in the SGA Implement Automatic Shared Memory Management Manually configure SGA parameters Configure automatic PGA memory management Memory Management: Overview DBAs must consider memory management to be a crucial part of their job because: There is a finite amount of memory available Allocating more memory to serve certain types of functions can improve overall performance Automatically tuned memory allocation is often the appropriate configuration, but specific environments or even short-term conditions may require further attention Memory Management: Overview Because there is a finite amount of memory available on a database server and thus, on an Oracle database instance, you must pay attention to how memory is allocated. If too much memory is allowed to be used by a particular area that does not need it, then there is the possibility that there are other . | Monitoring and Managing Memory Objectives After completing this lesson, you should be able to: Describe the memory components in the SGA Implement Automatic Shared Memory Management Manually configure SGA parameters Configure automatic PGA memory management Memory Management: Overview DBAs must consider memory management to be a crucial part of their job because: There is a finite amount of memory available Allocating more memory to serve certain types of functions can improve overall performance Automatically tuned memory allocation is often the appropriate configuration, but specific environments or even short-term conditions may require further attention Memory Management: Overview Because there is a finite amount of memory available on a database server and thus, on an Oracle database instance, you must pay attention to how memory is allocated. If too much memory is allowed to be used by a particular area that does not need it, then there is the possibility that there are other functional areas unnecessarily doing without enough memory to perform optimally. With the ability to have memory allocation automatically determined and maintained for you, the task is simplified greatly. But even automatically tuned memory needs to be monitored for optimization and may need to be manually configured to some extent. Beyond the introduction to memory tuning presented in the Oracle Database 10g: Administration Workshop I course, this lesson describes how automatic memory tuning works, when to do manual tuning, what the Program Global Area (PGA) is, and details of each of the memory structures in an Oracle instance. Oracle Memory Structures SGA Java pool Database buffer cache Shared pool Redo log buffer Large pool Streams pool Server process 1 PGA Server process 2 PGA Back- ground process PGA Keep buffer cache Recycle buffer cache nK block size buffer caches Oracle Memory Structures The basic memory structures associated with an Oracle instance include: System Global .