28.Oracle杂记——Oracle常用动态视图v$rollstat

28.Oracle杂记——Oracle常用动态视图v$rollstat
视图v$rollstat：联机回滚段统计信息     

描述如下：

sys@PDB1> desc v$rollstat;

 Name                                                                                                     Null?         Type

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

 USN                                                                                                                                     NUMBER

 LATCH                                                                                                                                 NUMBER

 EXTENTS                                                                                                                            NUMBER

 RSSIZE                                                                                                                              NUMBER

 WRITES                                                                                                                            NUMBER

 XACTS                                                                                                                                 NUMBER

 GETS                                                                                                                                   NUMBER

 WAITS                                                                                                                                NUMBER

 OPTSIZE                                                                                                                            NUMBER

 HWMSIZE                                                                                                                         NUMBER

 SHRINKS                                                                                                                            NUMBER

 WRAPS                                                                                                                                                 NUMBER

 EXTENDS                                                                                                                           NUMBER

 AVESHRINK                                                                                                                      NUMBER

 AVEACTIVE                                                                                                                      NUMBER

 STATUS                                                                                                                            VARCHAR2(15)

 CUREXT                                                                                                                             NUMBER

 CURBLK                                                                                                                             NUMBER

 CON_ID                                                                                                                            NUMBER

各个列描述如下：

USN：回滚段号

 LATCH：回滚段的LATCH

 EXTENTS：回滚段区数量

 RSSIZE：回滚段大小

 WRITES ：写到回滚段的字节数

 XACTS：活动的交易数量

 GETS： 获取的头数量

 WAITS：等待头的数量

 OPTSIZE                ：回滚段的合理大小

 HWMSIZE：回滚段大小的高水位

 SHRINKS                ：回滚段减少的次数

 WRAPS：回滚段SWAP的次数

 EXTENDS： 回滚段大小扩展的次数

 AVESHRINK：平均SHRINK 大小

 AVEACTIVE：平均活动区大小

 STATUS：回滚段状态

 CUREXT：当前区

 CURBLK ：当前块

 CON_ID：容器ID