In memory undolatch 0 0 0 0
In memory undolatch 0 0 0 0
In memory undolatch 0 0 0 0
In memory undolatch 0 0 0 0
In memory undolatch 4 0 2 0
In memory undolatch 214 0 25 0
In memory undolatch 6118 0 3064 0
In memory undolatch 4230 0 1084 0
In memory undolatch 39583 0 2842 0
18 rows selected.
除了前面提到的，还有几个隐含参数与IMU有关：
·_recursive_imu_transactions：控制递归事务是否使用IMU，该参数缺省值为False；
sys@TQGZS> @GetHidPar.sql
Enter value for par: _recursive_imu_transactions
old 4: AND x.ksppinm LIKE '%&par%'
new 4: AND x.ksppinm LIKE '%_recursive_imu_transactions%'
NAME VALUE DESCRIB
------------------------------ --------------------------------------------------------------------------------
_recursive_imu_transactions FALSE recursive transactions may be IMU
·_db_writer_flush_imu：控制是否允许DBWR将IMU事务的降级为常规事务，并执行UNDO SEGMENT的写出操作，缺省值为TRUE。
sys@TQGZS> @GetHidPar.sql
Enter value for par: _db_writer_flush_imu
old 4: AND x.ksppinm LIKE '%&par%'
new 4: AND x.ksppinm LIKE '%_db_writer_flush_imu%'
NAME VALUE DESCRIB
------------------------------ --------------------------------------------------------------------------------
_db_writer_flush_imu TRUE If FALSE, DBWR will not downgrade IMU txns for AGING
此外，在RAC环境中，IMU不被支持。
经过不同版本Oracle技术的不断演进，Oracle的内存管理已经和以前大为不同，现在Buffer Cache、Shared Pool、Log Buffer的内容正在不断交换渗透，Redo、Undo数据都可以部分地存储在共享池中，Oracle 11g的Result Cache也被记录在Shared Pool当中。
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