-
编辑 删除
Specifying the Large Pool Size (112)
The LARGE_POOL_SIZE initialization parameter is a dynamic parameter that lets you specify or adjust the size of the large pool component of the SGA. The large pool is an optional component of the SGA. You must specifically set the LARGE_POOL_SIZE parameter if you want to create a large pool. Configuring the large pool is discussed in Oracle Database Performance Tuning Guide.[@more@]
-
编辑 删除
Specifying the Java Pool Size (113)
The JAVA_POOL_SIZE initialization parameter is a dynamic parameter that lets you specify or adjust the size of the java pool component of the SGA. Oracle Database selects an appropriate default value. Configuration of the java pool is discussed in Oracle Database Java Developer's Guide.[@more@]
-
编辑 删除
Specifying the Shared Pool Size (111)
The SHARED_POOL_SIZE initialization parameter is a dynamic parameter that lets you specify or adjust the size of the shared pool component of the SGA. Oracle Database selects an appropriate default value.In releases before Oracle Database 10g Release 1, the amount of shared pool memory that was allocated was equal to the value of the SHARED_POOL_SIZE initialization parameter plus the amount of internal SGA overhead computed during instance startup. The internal SGA overhead refers to memory that
-
编辑 删除
The DB_nK_CACHE_SIZE Initialization Parameters (110)
The sizes and numbers of nonstandard block size buffers are specified by the following initialization parameters:■ DB_2K_CACHE_SIZE ■ DB_4K_CACHE_SIZE ■ DB_8K_CACHE_SIZE ■ DB_16K_CACHE_SIZE ■ DB_32K_CACHE_SIZE Each parameter specifies the size of the buffer cache for the corresponding block size. For example:DB_BLOCK_SIZE=4096DB_CACHE_SIZE=12MDB_2K_CACHE_SIZE=8MDB_8K_CACHE_SIZE=4MIn this example, the parameters specify that the standard block size of the database is 4K. The size of the cach
-
编辑 删除
Setting the Buffer Cache Initialization Parameters (108)
The buffer cache initialization parameters determine the size of the buffer cache component of the SGA. You use them to specify the sizes of caches for the various block sizes used by the database. These initialization parameters are all dynamic.If you intend to use multiple block sizes in your database, you must have the DB_CACHE_SIZE and at least one DB_nK_CACHE_SIZE parameter set. Oracle Database assigns an appropriate default value to the DB_CACHE_SIZE parameter, but the DB_nK_CACHE_SIZE par
-
编辑 删除
DB_CACHE_SIZE Initialization Parameter (109)
The DB_CACHE_SIZE initialization parameter has replaced the DB_BLOCK_BUFFERS initialization parameter, which was used in earlier releases. The DB_CACHE_SIZE parameter specifies the size in bytes of the cache of standard block size buffers. Thus, to specify a value for DB_CACHE_SIZE, you would determine the number of buffers that you need and multiple that value times the block size specified in DB_BLOCK_SIZE.For backward compatibility, the DB_BLOCK_BUFFERS parameter still functions, but it remai
-
编辑 删除
Using Manual Shared Memory Management (107)
If you decide not to use automatic shared memory management by not setting the SGA_TARGET parameter, you must manually configure each component of the SGA. This section provides guidelines on setting the parameters that control the size of each SGA components.[@more@]
-
编辑 删除
Modifying Parameters for Manually Sized Components (106)
Parameters for manually sized components can be dynamically altered as well. However, rather than setting a minimum size, the value of the parameter specifies the precise size of the corresponding component. When you increase the size of a manually sized component, extra memory is taken away from one or more automatically sized components. When you decrease the size of a manually sized component, the memory that is released is given to the automatically sized components.For example, consider thi
-
编辑 删除
Modifying Parameters for Automatically Managed Components (105)
When SGA_TARGET is not set, the automatic shared memory management feature is not enabled. Therefore the rules governing resize for all component parameters are the same as in earlier releases. However, when automatic shared memory management is enabled, the manually specified sizes of automatically sized components serve as a lower bound for the size of the components. You can modify this limit dynamically by changing the values of the corresponding parameters.If the specified lower limit for t
-
编辑 删除
Modifying Parameters for Automatically Managed Components (104)
When SGA_TARGET is not set,the automatic shared memory management feature is not enabled. Therefore the rulesgoverning resize for all component parameters are the same as in earlier releases.However, when automatic shared memory management is enabled, the manuallyspecified sizes of automatically sized components serve as a lower bound for the sizeof the components. You can modify this limit dynamically by changing the values ofthe corresponding parameters.If the specified lower limit for the siz
-
编辑 删除
Dynamic Modification of SGA_TARGET (103)
The SGA_TARGET parameter can be increased upto the value specified for the SGA_MAX_SIZE parameter, and it can also be reduced. Ifyou reduce the value of SGA_TARGET, the system identifies one or more automaticallytuned components for which to release memory. You can reduce SGA_TARGET untilone or more automatically tuned components reach their minimum size. OracleDatabase determines the minimum allowable value for SGA_TARGET taking intoaccount several factors, including values set for the automati
-
编辑 删除
Dynamic Modification of SGA Parameters (102)
You can modify the value of SGA_TARGET andthe parameters controlling individual components dynamically using the ALTERSYSTEM statement, as described in "Using ALTER SYSTEM to Change InitializationParameter Values" on page2-38.[@more@]
-
编辑 删除
Automatic Tuning and the Shared Pool (101)
When the automatic shared memory management feature is enabled, the internal tuningalgorithm tries to determine an optimal size forthe shared pool based on the workload. It usually converges on this value byincreasing in small increments over time. However, the internal tuning algorithmtypically does not attempt to shrink the shared pool, because the presence of opencursors, pinned PL/SQL packages, and other SQL execution state in the shared poolmake it impossible to find granules that can be fr
-
编辑 删除
Setting Minimums for Automatically Sized SGA Components (100)
You can exercise some control over the size of the automatically sized SGA components byspecifying minimum values for the parameters corresponding to these components. Doing socan be useful if you know that an application cannot function properly without a minimumamount of memory in specific components. You specify the minimum amount of SGA spacefor a component by setting a value for its corresponding initialization parameter. Hereis an example configuration:■ SGA_TARGET = 256M■ SHARED_POOL_SI
