已索引
一句话：存量系统看需求，新系统直接19c！以后的内容可以不用看了。如果想更深入了解，再看看。
19c实际发布时间在2019.5月。Oracle下一个计划的长期支持版本是23c。
关于Oracle版本，可以查看：Release Schedule of Current Database Releases (Doc ID 742060.1)。
Oracle 数据库有两种发行版本：
- Long Term Release
- Innovation Release
Long Term Release:
该版本提供更高级别的稳定性和最长的支持时间：至少5年标准服务(Premier Support)和3年扩展服务(Extended Support)。并且可能会根据需要延长标准服务时间或者免除扩展服务的费用。
Innovation Release:
在Long Term Release之间，Oracle会发布Innovation Releases，该版本会加进一些将来包含在下一个Long Term Release中的高级功能和新特性。Innovation Releases旨在让用户能够使用前沿科技，至少会提供2年的标准服务，但没有扩展服务。
Oracle关于版本的升级建议：
For product longevity and patching, Oracle strongly recommends upgrading to 19c which is the Long Term Release with a support end date of April 30, 2027 (or April 30, 2025 if you choose not to pay Extended Support fees or purchase a ULA).
If you are currently running 11.2.x/12.1.x you will need to upgrade to the terminal release (i.e. 11.2.0.4/12.1.0.2) for the DB Release you are running and then continue the upgrade process by upgrading to the 19c. 11.2.0.4 is in Sustaining Support with Market Driven Support available for some platforms. 12.1.0.2 is in Sustaining Support with Market Driven Support available beginning January 1, 2023 for some platforms.
If you are currently running 12.2.0.1 or 18c, you should upgrade to 19c without delay. 18c and 12.2 are in Sustaining Support.
关于18c = 12.2.02，19c=12.2.0.3：
There is no 12.2.0.3 version. After 12.2.0.1 Oracle did change there release naming convention. Now it is base on the year starting from 2018. Accordingly it would be 18c, 19c and so on. Currently 19c is the long term support release. You should there by plan on upgrading from 12.2.0.1 to 19c. Then you can apply the latest RU which would result in 19.11.
I believe in some circles (or unofficially) people refer 18c as 12.2.0.2 and 19c as 12.2.03. However as mentioned above Oracle documentation refers to 12.2 followed by 18c, 19c, etc.
