一、概念

• SHARED_POOL_SIZE --大小
• SHARED_POOL_RESERVED_SIZE --保留区大小
• _SHARED_POOL_RESERVED_MIN_ALLOC --请求的内存是否放入保留池的阈值，默认4400,如果在共享池空闲列表中找不到足够大小的内存块，则大于此值的内存分配可以从保留区中分配空间

1.1、查看该参数默认值

SELECT nam.ksppinm NAME,val.ksppstvl VALUE FROM x$ksppi nam,x$ksppsv val WHERE nam.indx = val.indx AND nam.ksppinm LIKE '%shared%' ORDER BY 1;

NAME                                     VALUE
---------------------------------------- ------------------------------------------------------------
_shared_io_pool_debug_trc                0
_shared_io_pool_size                     134217728
_shared_io_set_value                     FALSE
_shared_iop_max_size                     134217728
_shared_pool_max_size                    0
_shared_pool_max_sz                      0
_shared_pool_minsize_on                  FALSE
_shared_pool_reserved_min_alloc          4400
_shared_pool_reserved_pct                5
_shared_server_load_balance              0
_shared_server_num_queues                2

1.2、查看sga中各组件大小

select * from V$SGA_DYNAMIC_COMPONENTS;
COMPONENT                      CURRENT_SIZE   MIN_SIZE   MAX_SIZE USER_SPECIFIED_SIZE OPER_COUNT LAST_OPER_TYPE             LAST_OPER_MODE     LAST_OPER_TIME      GRANULE_SIZE     CON_ID
------------------------------ ------------ ---------- ---------- ------------------- ---------- -------------------------- ------------------ ------------------- ------------ ----------
shared pool                      1761607680 1409286144 1761607680                   0          5 GROW                       DEFERRED           2022-04-12 22:01:44     16777216          0
large pool                         33554432   33554432   33554432                   0          0 STATIC                                                                16777216          0
java pool                                 0          0          0                   0          0 STATIC                                                                16777216          0
streams pool                              0          0          0                   0          0 STATIC                                                                16777216          0
unified pga pool                          0          0          0                   0          0 STATIC                                                                16777216          0
memoptimize buffer cache                  0          0          0                   0          0 STATIC                                                                16777216          0
DEFAULT buffer cache             4966055936 4966055936 5318377472                   0          5 SHRINK                     DEFERRED           2022-04-12 22:01:44     16777216          0
KEEP buffer cache                         0          0          0                   0          0 STATIC                                                                16777216          0
RECYCLE buffer cache                      0          0          0                   0          0 STATIC                                                                16777216          0
DEFAULT 2K buffer cache                   0          0          0                   0          0 STATIC                                                                16777216          0
DEFAULT 4K buffer cache                   0          0          0                   0          0 STATIC                                                                16777216          0

COMPONENT                      CURRENT_SIZE   MIN_SIZE   MAX_SIZE USER_SPECIFIED_SIZE OPER_COUNT LAST_OPER_TYPE             LAST_OPER_MODE     LAST_OPER_TIME      GRANULE_SIZE     CON_ID
------------------------------ ------------ ---------- ---------- ------------------- ---------- -------------------------- ------------------ ------------------- ------------ ----------
DEFAULT 8K buffer cache                   0          0          0                   0          0 STATIC                                                                16777216          0
DEFAULT 16K buffer cache                  0          0          0                   0          0 STATIC                                                                16777216          0
DEFAULT 32K buffer cache                  0          0          0                   0          0 STATIC                                                                16777216          0