Area #0 `Fixed Size' containing Subareas 0-0               
  Total size 00000000001299c8 Minimum Subarea size 00000000 
   Area  Subarea    Shmid      Stable Addr      Actual Addr 
      0        0    65536 0x00000020000000 0x00000020000000      Low Address|--Stable addr of Fixed SGA:0x00000020000000  对照开始的图
                              Subarea size     Segment size                 |
                          000000000012a000 0000000011a00000                 |--Segment size 11a00000=282M=(sga_max_size)    SQL> show parameter sga_max                                                   
 Area #1 `Variable Size' containing Subareas 2-2                            |                                                            
  Total size 0000000011000000 Minimum Subarea size 00400000                 |                                               NAME              TYPE        VALUE                        
   Area  Subarea    Shmid      Stable Addr      Actual Addr                 |                                               ----------------- ----------- ---------
      1        2    65536 0x00000020800000 0x00000020800000                 |--Stable addr of Variable:0x00000020800000   sga_max_size      big integer 280M                         
                              Subarea size     Segment size                 |
                          0000000011000000 0000000011a00000                 |
 Area #2 `Redo Buffers' containing Subareas 1-1                             |
  Total size 00000000006d6000 Minimum Subarea size 00000000                 |
   Area  Subarea    Shmid      Stable Addr      Actual Addr                 |
      2        1    65536 0x0000002012a000 0x0000002012a000                 |--Stable addr of Redo Buffer:0x0000002012a000
                              Subarea size     Segment size                 |
                          00000000006d6000 0000000011a00000                 |
 Area #3 `skgm overhead' containing Subareas 3-3                            |
  Total size 0000000000001000 Minimum Subarea size 00000000                 |
   Area  Subarea    Shmid      Stable Addr      Actual Addr                 |
      3        3    65536 0x00000031800000 0x00000031800000     High Address|--Stable addr of OS Specified:0x00000031800000
                              Subarea size     Segment size                 (*地址是从低到高*)
 
                          0000000000001000 0000000011a00000 
验证地址的连续性:variable --redo buffe
SQL> select to_number('20800000','xxxxxxxxx') from dual;
TO_NUMBER('20800000','XXXXXXXX
------------------------------
                     545259520

验证前面的结构图