SGA包含的组件：
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组件名
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说明
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参数
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buffer cache
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存放从数据文件中读取的数据拷贝，所有用户之间是可以共享的
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db_cache_size
db_keep_cache_size
db_recycle_cache_size
db_nk_cache_size
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redo log buffer
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redo数据
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log_buffer
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shared pool
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存放库缓存和数据字典缓存，结果缓存，并行执行消息缓存，以及控制结构信息
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shared_pool_size
shared_pool_reserved_size
result_cache_max_size*
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large pool
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共享模式下为会话分配内存，oracle xa，并行查询缓存，rman
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large_pool_size
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java pool
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为java代码分配内存
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java_pool_size
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streams pool
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用于oracle stream
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streams_pool_size
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1.AMM(Automatic Memory Management) – 统一管理SGA和PGA
-memory_target
-memory_max_target
2.ASSM(Automatic Shared Memory Management) – 自动管理SGA
自动管理SGA(buffer cache、shared pool、large pool、java pool、streams pool)，使用$sga_target_advice进行调优
-sga_target：动态参数
-sga_max_size
在ASSM中以下部分不受管理：
-Log buffer
-Other buffer caches (such as KEEP, RECYCLE, and other nondefault block size)
-Fixed SGA and other internal allocations
SQL> select * from v$sga_target_advice;
SGA_SIZE SGA_SIZE_FACTOR ESTD_DB_TIME ESTD_DB_TIME_FACTOR ESTD_PHYSICAL_READS
---------- --------------- ------------ ------------------- -------------------
7264 .25 1187001 4.5075 3994550959
10896 .375 453075 1.7205 1350811286
14528 .5 276980 1.0518 585978929
18160 .625 263602 1.001 525730243
21792 .75 263339 1 525730243
25424 .875 263339 1 525730243
29056 1 263339 1 525730243
32688 1.125 263339 1 525730243
36320 1.25 263339 1 525730243
39952 1.375 263339 1 525730243
43584 1.5 263339 1 525730243
47216 1.625 263339 1 525730243
50848 1.75 218598 .8301 325059009
54480 1.875 218492 .8297 325059009
58112 2 218492 .8297 325059009
15 rows selected.
SQL>
3.manual shared memory management – 手动管理SGA
手工管理SGA的时候，需要手动设置以下参数的值：
-db_cache_size
-java_pool_size
-large_pool_size
-log_buffer
-shared_pool_size
oracle在为这些组件分配内存的时候，以granules为单位。SGA<1G时，granules以4mb为单位；SGA>1G时，granules以16mb为单位
调优涉及的部分视图：
v$memory_resize_ops
SQL> select * from v$memory_resize_ops; COMPONENT OPER_TYPE OPER_MODE PARAMETER INITIAL_SIZE TARGET_SIZE FINAL_SIZE STATUS START_TIM END_TIME ------------------------------ ------------- --------- ------------------------------ ------------ ----------- ---------- --------- --------- --------- shared pool STATIC shared_pool_size 0 6576668672 6576668672 COMPLETE 26-DEC-15 26-DEC-15 PGA Target STATIC pga_aggregate_target 0 1.0201E+10 1.0201E+10 COMPLETE 26-DEC-15 26-DEC-15 java pool STATIC java_pool_size 0 469762048 469762048 COMPLETE 26-DEC-15 26-DEC-15 streams pool STATIC streams_pool_size 0 134217728 134217728 COMPLETE 26-DEC-15 26-DEC-15 SGA Target STATIC sga_target 0 3.0467E+10 3.0467E+10 COMPLETE 26-DEC-15 26-DEC-15 DEFAULT buffer cache INITIALIZING db_cache_size 2.2817E+10 2.2817E+10 2.2817E+10 COMPLETE 26-DEC-15 26-DEC-15 ASM Buffer Cache STATIC db_cache_size 0 0 0 COMPLETE 26-DEC-15 26-DEC-15 DEFAULT buffer cache STATIC db_cache_size 0 2.2817E+10 2.2817E+10 COMPLETE 26-DEC-15 26-DEC-15 DEFAULT 2K buffer cache STATIC db_2k_cache_size 0 0 0 COMPLETE 26-DEC-15 26-DEC-15 DEFAULT 4K buffer cache STATIC db_4k_cache_size 0 0 0 COMPLETE 26-DEC-15 26-DEC-15 DEFAULT 8K buffer cache STATIC db_8k_cache_size 0 0 0 COMPLETE 26-DEC-15 26-DEC-15 DEFAULT 16K buffer cache STATIC db_16k_cache_size 0 0 0 COMPLETE 26-DEC-15 26-DEC-15 DEFAULT 32K buffer cache STATIC db_32k_cache_size 0 0 0 COMPLETE 26-DEC-15 26-DEC-15 KEEP buffer cache STATIC db_keep_cache_size 0 0 0 COMPLETE 26-DEC-15 26-DEC-15 RECYCLE buffer cache STATIC db_recycle_cache_size 0 0 0 COMPLETE 26-DEC-15 26-DEC-15 large pool STATIC large_pool_size 0 268435456 268435456 COMPLETE 26-DEC-15 26-DEC-15 16 rows selected. SQL>
v$memory_target_advice
v$sga_current_resize_ops
v$sga_resize_ops
SQL> select * from v$sga_resize_ops; COMPONENT OPER_TYPE OPER_MODE PARAMETER INITIAL_SIZE TARGET_SIZE FINAL_SIZE STATUS START_TIM END_TIME ------------------------------ ------------- --------- ------------------------------ ------------ ----------- ---------- --------- --------- --------- shared pool STATIC shared_pool_size 0 6576668672 6576668672 COMPLETE 26-DEC-15 26-DEC-15 large pool STATIC large_pool_size 0 268435456 268435456 COMPLETE 26-DEC-15 26-DEC-15 java pool STATIC java_pool_size 0 469762048 469762048 COMPLETE 26-DEC-15 26-DEC-15 streams pool STATIC streams_pool_size 0 134217728 134217728 COMPLETE 26-DEC-15 26-DEC-15 DEFAULT buffer cache INITIALIZING db_cache_size 2.2817E+10 2.2817E+10 2.2817E+10 COMPLETE 26-DEC-15 26-DEC-15 ASM Buffer Cache STATIC db_cache_size 0 0 0 COMPLETE 26-DEC-15 26-DEC-15 RECYCLE buffer cache STATIC db_recycle_cache_size 0 0 0 COMPLETE 26-DEC-15 26-DEC-15 DEFAULT 2K buffer cache STATIC db_2k_cache_size 0 0 0 COMPLETE 26-DEC-15 26-DEC-15 DEFAULT 4K buffer cache STATIC db_4k_cache_size 0 0 0 COMPLETE 26-DEC-15 26-DEC-15 DEFAULT 8K buffer cache STATIC db_8k_cache_size 0 0 0 COMPLETE 26-DEC-15 26-DEC-15 DEFAULT 16K buffer cache STATIC db_16k_cache_size 0 0 0 COMPLETE 26-DEC-15 26-DEC-15 DEFAULT 32K buffer cache STATIC db_32k_cache_size 0 0 0 COMPLETE 26-DEC-15 26-DEC-15 KEEP buffer cache STATIC db_keep_cache_size 0 0 0 COMPLETE 26-DEC-15 26-DEC-15 DEFAULT buffer cache STATIC db_cache_size 0 2.2817E+10 2.2817E+10 COMPLETE 26-DEC-15 26-DEC-15 14 rows selected. SQL>
v$sga_dynamic_components
SQL> select * from v$sga_dynamic_components; COMPONENT CURRENT_SIZE MIN_SIZE MAX_SIZE USER_SPECIFIED_SIZE OPER_COUNT LAST_OPER_TYP LAST_OPER LAST_OPER GRANULE_SIZE ------------------------------ ------------ ---------- ---------- ------------------- ---------- ------------- --------- --------- ------------ shared pool 6576668672 6576668672 6576668672 0 0 STATIC 67108864 large pool 268435456 268435456 268435456 0 0 STATIC 67108864 java pool 469762048 469762048 469762048 0 0 STATIC 67108864 streams pool 134217728 134217728 134217728 0 0 STATIC 67108864 DEFAULT buffer cache 2.2817E+10 2.2817E+10 2.2817E+10 0 0 INITIALIZING 67108864 KEEP buffer cache 0 0 0 0 0 STATIC 67108864 RECYCLE buffer cache 0 0 0 0 0 STATIC 67108864 DEFAULT 2K buffer cache 0 0 0 0 0 STATIC 67108864 DEFAULT 4K buffer cache 0 0 0 0 0 STATIC 67108864 DEFAULT 8K buffer cache 0 0 0 0 0 STATIC 67108864 DEFAULT 16K buffer cache 0 0 0 0 0 STATIC 67108864 DEFAULT 32K buffer cache 0 0 0 0 0 STATIC 67108864 Shared IO Pool 0 0 0 0 0 STATIC 67108864 ASM Buffer Cache 0 0 0 0 0 STATIC 67108864 14 rows selected. SQL>
v$sga_dynamic_free_memory
SQL> select * from v$sga_dynamic_free_memory;
CURRENT_SIZE CON_ID
------------ ----------
50331648 0
SQL>