Oracle Database 内存管理

SGA
SQL> show parameter sga_target
NAME                                 TYPE                              VALUE
------------------------------------ --------------------------------- ------------------------------
sga_target                           big integer                       1G

SQL> show parameter sga_max_size
NAME                                 TYPE                              VALUE
------------------------------------ --------------------------------- ------------------------------
sga_max_size                         big integer                       1G

SQL> select name,value/1024/1024 as "SIZE (MB)" from v$sga;
NAME                                                          SIZE (MB)
------------------------------------------------------------ ----------
Fixed Size                                                   2.11734772
Variable Size                                                276.003746
Database Buffers                                                    736
Redo Buffers                                                   5.296875

DB BUFFER CACHE
SQL> show parameter db_block_size
NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
db_block_size                        integer     8192

SQL> select * from v$sgainfo where name='Granule Size';
NAME                                  BYTES RES
-------------------------------- ---------- ---
Granule Size                       16777216 No

SQL> select 16777216/8192 from dual; -- granule中包含2048个buffer
16777216/8192
-------------
         2048
         
SQL> select * from v$sgainfo where name='Buffer Cache Size';
NAME                                  BYTES RES
-------------------------------- ---------- ---
Buffer Cache Size                 771751936 Yes

SQL> select 771751936/1024/1024 from dual;
771751936/1024/1024
-------------------
                736
                
SQL> select 771751936/8192 from dual;  --db_cache中包含94208个buffer
771751936/8192
--------------
         94208
         
SQL> select 94208/2048 from dual; --db_cache由46个granule组成
94208/2048
----------
        46