１、SGA_TARGET始终要= SGA_MAX_SIZE 否则 ORA-00823: Specified value ofsga_target greater than sga_max_size AMM启动时（即memory_target=非0） 1、sga_target《memory_target《memory_max_target 如果 sga_targetmemory_target，则会提示： ORA-00838:
１、SGA_TARGET始终要<=SGA_MAX_SIZE
否则
ORA-00823: Specified value ofsga_target greater than sga_max_size
AMM启动时（即memory_target=非0）
1、sga_target《memory_target《memory_max_target
如果sga_target>memory_target，则会提示：
ORA-00838:指定的 MEMORY_TARGET 的值太小, 至少应为 XXXX M（该值等于sga_target与pga_aggregate_target之和，
因为MEMORY_TARGET》=sga_target与pga_aggregate_target之和）
2、sga_max_size《memory_target ，否则
ORA-00851:SGA_MAX_SIZE 780140544 cannot be set to more than MEMORY_TARGET 41943
0400.
AMM关闭时（即memory_target=0）
1、sga_target ORA-00849:SGA_TARGET 524288000 cannot be set to more than MEMORY_MAX_TARGET 0. 2、sga_max_size可以大于memory_max_target吗？ 在参数文件里，即使当sga_target《memory_max_target时，如果sga_max_size>memory_max_target，则启动实例时也不会成功，也会出现提示与sga_target>memory_max_target时相同的提示：ORA-00849:SGA_TARGET
524288000 cannot be set to more than MEMORY_MAX_TARGET 0. 只当参数文件里sga_max_size和memory_max_target都为0时，启动实例后，显示的sga_max_size可以大于memory_max_target。 总之， AMM启动时（即memory_target=非0），sga_max_size《memory_target： sga_target《sga_max_size《memory_target AMM关闭时（即memory_target=0），由于memory_target=0相当于说memory_target这个参数不起作用此时，所以sga_max_size《memory_max_target： 原本以为 AMM启动时（即memory_target=非0），sga_target只要《memory_target，以及<=SGA_MAX_SIZE就行，sga_max_size和memory_target间可以无相关关系；AMM关闭时（即memory_target=0），sga_target只要《memory_max_target以及<=SGA_MAX_SIZE就行，sga_max_size和memory_max_target间可以无相关关系。 事实是，在sga_max_size和memory_max_target（或是memory_target）间是有相关关系的。 估计因为oracle公司设计程序时考虑到如下效率问题吧： 如果在sga_max_size和memory_max_target（或是memory_target）间无相关关系时， 每次修改一次sga_target的值，程序都要进行两次判断sga_target修改后的值是否符合条件： 一是sga_target是否《memory_max_target（或是memory_target），二是sga_target是否<=SGA_MAX_SIZE 而如果在sga_max_size和memory_max_target（或是memory_target）间有相关关系，即sga_max_size
<=memory_max_target（或是memory_target）时， 每次修改一次sga_target的值，程序只要进行一次判断sga_target修改后的值是否符合条件即可： sga_target是否<=SGA_MAX_SIZE. 注释小结： 1、AMM启动时（即memory_target=非0），才会出现 ORA-00851:SGA_MAX_SIZE 780140544 cannot be set to more than MEMORY_TARGET 41943 AMM启动时（即memory_target=非0）且sga_max_size>memory_target时，才会出现 ORA-00851。 当memory_target=0时，由于memory_target=0而使memory_target参数不起作用，所以以memory_max_target为标准线，sga_max_size和sga_target围绕memory_max_target，即sga_max_size和sga_target与memory_max_target间有关系存在。 2、 启动实例时 SGA_TARGET要小于等于MEMORY_MAX_TARGET ORA-00849（MEMORY_TARGET=0AMM关闭下，当SGA_MAX_SIZE大于等于MEMORY_MAX_TARGET时就会发生ORA-00849，即使SGA_TARGET小于等于MEMORY_MAX_TARGET也会发生ORA-00849） SGA_MAX_SIZE
要小于等于 MEMORY_TARGET
ORA-00851 （当SGA_MAX_SIZE =非0，MEMORY_TARGET=0时例外，因为MEMORY_TARGET=0AMM关闭即MEMORY_TARGET参数不起作用，所以此时SGA_MAX_SIZE
与MEMORY_TARGET无关系） 实例运行时 SGA_MAX_SIZE 可以大于（修改后的）MEMORY_TARGET 无论启动实例时，还是实例运行时 MEMORY_TARGET要小于等于MEMORY_MAX_TARGET （启动实例前，MEMORY_TARGET=非0，MEMORY_MAX_TARGET=0例外） SGA_TARGET要小于等于SGA_MAX_SIZE MEMORY_TARGET》=sga_target与pga_aggregate_target之和 因为无论启动实例时，还是实例运行时 MEMORY_TARGET》=sga_target与pga_aggregate_target之和 所以SGA_TARGET始终要小于等于MEMORY_TARGET 注释： 如果两个参数都是静态或是动态参数，那讨论她两关系时就不用区分实例启动前修改它们值和实例启动后（即实例运行时）修改它们值两个阶段。 如果两个参数，一个是静态，一个是动态参数，那讨论她两关系时就要区分实例启动前修改它们值和实例启动后（即实例运行时）修改它们值两个阶段。同一个层级上的两个参数只讨论实例启动前修改它们值这个阶段。例如，MEMORY_TARGET和MEMORY_MAX_TARGET MEMORY_TARGET要小于等于MEMORY_MAX_TARGET， 当MEMORY_TARGET=非0，MEMORY_MAX_TARGET=0时，启动实例后MEMORY_MAX_TARGET=MEMORY_TARGET值。 上下层级的两个参数区分实例启动前修改它们值和实例启动后（即实例运行时）修改它们值两个阶段来讨论。例如，SGA_MAX_SIZE和 MEMORY_TARGET 启动实例时 SGA_MAX_SIZE
要小于等于 MEMORY_TARGET
ORA-00851 实例运行时 SGA_MAX_SIZE 可以大于（修改后的）MEMORY_TARGET 因为 memory_max_target是静态参数，其实例运行期间修改的值在实例运行期间不起作用，该参数只在实例启动时起作用。 附加注释： 实例以workarea_size_policy=manual启动实例时可以在参数文件里pga_aggregate_target
可以设置为0，实例启动后显示的pga_aggregate_target
的值为0。 从这个结论，说明有些动态参数也要分实例启动前后讨论。 下面是实验： 提示ORA-00849: SGA_TARGET 1048576000(是1000M,不是500M)
cannot be setto more than MEMORY_MAX_TARGET 943718400. 参数: *.memory_max_target=900M *.memory_target=0 *.pga_aggregate_target=100M *.workarea_size_policy='AUTO' *.sga_max_size=1000M *.sga_target=500M SQL> startuppfile=E:\app\hc\product\11.2.0\dbhome_1\database\INITmonkey.ORA ORA-00843: Parameter not takingMEMORY_MAX_TARGET into account ORA-00849: SGA_TARGET 1048576000(是1000M,不是500M) cannot be setto more than
MEMORY_MAX_TARGET 943718400. ORA-01078: 处理系统参数失败 SQL> 参数: *.memory_max_target=900M *.memory_target=0 *.pga_aggregate_target=100M *.workarea_size_policy='AUTO' *.sga_max_size=1000M *.sga_target=950M SQL> startup pfile=E:\app\hc\product\11.2.0\dbhome_1\database\INITmonkey.ORA ORA-00843: Parameter not takingMEMORY_MAX_TARGET into account ORA-00849: SGA_TARGET 1048576000(是1000M,不是950M) cannot be setto more than
MEMORY_MAX_TARGET 94 3718400. ORA-01078: 处理系统参数失败 SQL> 参数: *.memory_max_target=900M *.memory_target=0 *.pga_aggregate_target=100M *.workarea_size_policy='AUTO' *.sga_max_size=1000M *.sga_target=1200M SQL> startuppfile=E:\app\hc\product\11.2.0\dbhome_1\database\INITmonkey.ORA ORA-00843: Parameter not takingMEMORY_MAX_TARGET into account ORA-00849: SGA_TARGET 1048576000(是1000M,不是1200M) cannotbe set to more than
MEMORY_MAX_TARGET 943718400. ORA-01078: 处理系统参数失败 SQL> 说明 同时出现sga_max_size< sga_target和memory_max_target 参数: *.memory_max_target=900M *.memory_target=0 *.pga_aggregate_target=100M *.workarea_size_policy='AUTO' *.sga_max_size=800M *.sga_target=1000M SQL> startuppfile=E:\app\hc\product\11.2.0\dbhome_1\database\INITmonkey.ORA ORA-00823:Specified value of sga_target greater than sga_max_size ORA-01078: 处理系统参数失败 SQL> 总之，memory_参数和sga_参数间的关系出错（即memory_max_target ；memory_ target 参数: *.memory_max_target=900M *.memory_target=0 *.pga_aggregate_target=100M *.workarea_size_policy='AUTO' *.sga_max_size=800M *.sga_target=700M SQL> startup pfile=E:\app\hc\product\11.2.0\dbhome_1\database\INITmonkey.ORA 启动实例成功 参数: *.memory_max_target=900M *.memory_target=0 *.pga_aggregate_target=100M *.workarea_size_policy='AUTO' *.sga_max_size=700M *.sga_target=800M SQL> startup pfile=E:\app\hc\product\11.2.0\dbhome_1\database\INITmonkey.ORA ORA-00823: Specified value of sga_targetgreater than sga_max_size ORA-01078: 处理系统参数失败 SQL> 说明 同时出现sga_max_size< sga_target和memory_max_target 附加： 当memory_target=0时，由于memory_target=0而使memory_target参数不起作用，所以以memory_max_target为标准线，sga_max_size和sga_target围绕memory_max_target，即sga_max_size和sga_target与memory_max_target间有关系存在。 提示ORA-00851: SGA_MAX_SIZE1048576000 cannot be set to more than MEMORY_TARGET 629145600. 参数: *.memory_max_target=900M *.memory_target=600M *.pga_aggregate_target=100M *.workarea_size_policy='AUTO' *.sga_max_size=1000M *.sga_target=500M SQL> shutdown immediate 数据库已经关闭。 已经卸载数据库。 ORACLE 例程已经关闭。 SQL> startup pfile=E:\app\hc\product\11.2.0\dbhome_1\database\INITmonkey.ORA ORA-00844: Parameter not takingMEMORY_TARGET into account ORA-00851: SGA_MAX_SIZE 1048576000 cannot be set to more thanMEMORY_TARGET 6291 45600. 注释： memory_max_target < sga_max_size时，还是提示memory_ target和
sga_max_size间的关系，说明memory_target=非0时是memory_target和
sga_max_size间有关系。 ORA-01078: 处理系统参数失败 SQL> 参数: *.memory_max_target=900M *.memory_target=600M *.pga_aggregate_target=100M *.workarea_size_policy='AUTO' *.sga_max_size=1000M *.sga_target=500M SQL> shutdown immediate 数据库已经关闭。 已经卸载数据库。 ORACLE 例程已经关闭。 SQL> startup pfile=E:\app\hc\product\11.2.0\dbhome_1\database\INITmonkey.ORA ORA-00844: Parameter not takingMEMORY_TARGET into account ORA-00851: SGA_MAX_SIZE 1048576000 cannot be set to more thanMEMORY_TARGET 6291 45600. ORA-01078: 处理系统参数失败 SQL> 参数: *.memory_max_target=900M *.memory_target=600M *.pga_aggregate_target=200M *.workarea_size_policy='AUTO' *.sga_max_size=1000M *.sga_target=500M SQL> shutdown immediate 数据库已经关闭。 已经卸载数据库。 ORACLE 例程已经关闭。 SQL> startup pfile=E:\app\hc\product\11.2.0\dbhome_1\database\INITmonkey.ORA ORA-00844: Parameter not takingMEMORY_TARGET into account ORA-00851: SGA_MAX_SIZE 1048576000 cannot be set to more thanMEMORY_TARGET 6291 45600. ORA-01078: 处理系统参数失败 SQL> 参数: *.memory_max_target=900M *.memory_target=600M *.pga_aggregate_target=200M *.workarea_size_policy='AUTO' *.sga_max_size=600M *.sga_target=500M SQL> startuppfile=E:\app\hc\product\11.2.0\dbhome_1\database\INITmonkey.ORA ORA-00838: Specifiedvalue of MEMORY_TARGET is too small, needs to be at least 7 00M ORA-01078: 处理系统参数失败 SQL> 说明 同时出现pga_aggregate_target与sga_target之和>memory_target和memory_ target < sga_max_size时，优先报错后者的相关错误消息，即ORA-00851:SGA_MAX_SIZE
1048576000 cannot be set to more than MEMORY_TARGET 6291 45600. 参数: *.memory_max_target=900M *.memory_target=600M *.pga_aggregate_target=100M *.workarea_size_policy='AUTO' *.sga_max_size=800M *.sga_target=700M SQL> startup pfile=E:\app\hc\product\11.2.0\dbhome_1\database\INITmonkey.ORA ORA-00844: Parameter not takingMEMORY_TARGET into account ORA-00851: SGA_MAX_SIZE 838860800 cannot beset to more than MEMORY_TARGET 62914 5600. ORA-01078: 处理系统参数失败 SQL> 参数: *.memory_max_target=900M *.memory_target=600M *.pga_aggregate_target=100M *.workarea_size_policy='AUTO' *.sga_max_size=700M *.sga_target=800M SQL> startuppfile=E:\app\hc\product\11.2.0\dbhome_1\database\INITmonkey.ORA ORA-00844: Parameter not takingMEMORY_TARGET into account ORA-00851: SGA_MAX_SIZE 734003200 cannot beset to more than MEMORY_TARGET 62914 5600. ORA-01078: 处理系统参数失败 SQL> 只有当memory_ target 〉 sga_max_size且memory_target 〉sga_target时，sga_max_size< sga_target才会抱错sga_max_size< sga_target的相关提示ora-00823。 参数: *.memory_max_target=900M *.memory_target=600M *.pga_aggregate_target=100M *.workarea_size_policy='AUTO' *.sga_max_size=500M *.sga_target=700M SQL> startup pfile=E:\app\hc\product\11.2.0\dbhome_1\database\INITmonkey.ORA ORA-00838: Specified value of MEMORY_TARGETis too small, needs to be at least 800M ORA-01078: 处理系统参数失败 SQL> memory_ target 〉 sga_max_size且 memory_target 同时memory_target MEMORY_TARGET sga_max_size 参数: *.memory_max_target=900M *.memory_target=700M *.pga_aggregate_target=0 *.workarea_size_policy='MANUAL' *.sga_max_size=600M *.sga_target=800M SQL> startuppfile=E:\app\hc\product\11.2.0\dbhome_1\database\INITmonkey.ORA ORA-00838: Specified value of MEMORY_TARGET is too small, needs to beat least 8 12M(粒度) ORA-01078: 处理系统参数失败 SQL> 当 同时出现MEMORY_TARGET< sga_target sga_max_size
sga_target《sga_max_size《memory_max_target
都是AMM程序里的参数：是AMM程序里上下层级上的参数：
memory_target=0
memory_max_target < sga_max_size：
memory_max_target >sga_target时
memory_max_target
sga_max_size> sga_target
sga_max_size< sga_target
memory_max_target > sga_max_size：
memory_max_target
memory_max_target >sga_target时
sga_max_size> sga_target
sga_max_size< sga_target
memory_target=非0
以memory_max_target为标准线，sga_max_size和sga_target围绕此
memory_max_target < sga_max_size且memory_target>sga_target时
以memory_ target为标准线，sga_max_size和sga_target围绕此。
memory_target < sga_max_size且memory_target >sga_target时
pga_aggregate_target与sga_target之和< memory_target
pga_aggregate_target与sga_target之和>memory_target
memory_ target < sga_max_size且memory_target
sga_max_size> sga_target
sga_max_size< sga_target
memory_ target 〉 sga_max_size且memory_target
