記憶體管理

對於OLTP系統：
PGA=例項記憶體*20%
SGA=例項記憶體*80%

對於OLAP系統：
PGA=例項記憶體*50%
SGA=例項記憶體*50%

sys@PROD>show parameter memory

NAME                                 TYPE        VALUE

------------------------------------ ----------- ------------------------------

hi_shared_memory_address             integer     0

memory_max_target                    big integer 800M

memory_target                        big integer 800M

shared_memory_address                integer     0

 
---檢視SGA引數：

PROD>show parameter sga

NAME                                 TYPE        VALUE

------------------------------------ ----------- ------------------------------

lock_sga                             boolean     FALSE

pre_page_sga                         boolean     FALSE

sga_max_size                         big integer 800M

sga_target                           big integer 0

---檢視PGA的引數：

sys@PROD>show parameter area_size

NAME                                 TYPE        VALUE

------------------------------------ ----------- ------------------------------

bitmap_merge_area_size               integer     1048576

create_bitmap_area_size              integer     8388608

hash_area_size                       integer     131072

sort_area_size                       integer     65536

workarea_size_policy                 string      AUTO

---三個（記憶體）引數一起檢視：

sys@PROD>show parameter target;

NAME                                 TYPE        VALUE

------------------------------------ ----------- ------------------------------

archive_lag_target                   integer     0

db_flashback_retention_target        integer     1440

fast_start_io_target                 integer     0

fast_start_mttr_target               integer     0

memory_max_target                    big integer 800M

memory_target                        big integer 800M

parallel_servers_target              integer     16

pga_aggregate_target                 big integer 0

sga_target                           big integer 0

#如果不想共享記憶體自動管理，可以將SGA_TARGET引數設定為非零值。

#可以透過控制hash_area_size與sort_area_size引數的值來控制PGA的使用。

--PGA自動或者抖動管理的引數：

sys@PROD>show parameter workarea_size_policy

NAME                                 TYPE        VALUE

------------------------------------ ----------- ------------------------------

workarea_size_policy                 string      AUTO

sys@PROD>

#該引數有兩個值：manual與auto，預設情況下，為auto值，即自動管理。