一直打RU补丁，未真正了解过RUR与RU之前关系，今天有机会与小伙伴讨论，修正了之前误区，特此记录。 从 2017 年 7 月开始，Oracle 对数据库和 GI(Grid Infrastructure) 12.2 及之后版本的主动修补程序进行了更改。Oracle 从 12.2 版本开始补丁不在使用 PSU、SPU 的称呼了， 取而代之的为 RU (Release Updates) 和 RUR (Release Update Revisions)
（1）RU、RUR均可独立打，均为累积性。RUR无需前置RU即可独立打补丁。
（2）RUR与RU可以互相转换打补丁序列，但需要遵循补丁后两位之和大于已打补丁，例如：
Example 1:
source - 18.2.2 <<<<< sum of second and third fields is "4"
destination - 18.5.0 <<<<< sum of second and third fields is "5"
conclusion: destination "5" is greater than or equal to source "4" so it is OK to move
Example 2:
source - 18.2.2 <<<<< sum of second and third fields is "4"
destination - 18.3.0 <<<<< sum of second and third fields is "3"
conclusion: destination "3" is less than source "4" so a patch application error is issued
（3）RUR最多可以有两次，即对RU的生命周期延长两个季度。
详细请参考附件以及下面链接：
Release Update Introduction and FAQ (Doc ID 2285040.1).pdfhttps://www.modb.pro/db/27255
