oracle升級后數據文件路徑變為大寫

進行數據文件維護時，發現數據文件的名稱存在大小寫差異。

在某個時間點以后創建的數據文件，名稱中的db_name和“datafile”都是大寫，而以前都是小寫。

查詢官方文檔 Directory for Datafiles and Controlfiles Become Uppercase in 18.3 DBCA. (Doc ID 2542927.1)

在18.3.0.0版本開始，內部設計上的變化導致了此問題。

同時還指向一個internal的文檔，無權限瀏覽：

BUG:29294715  - 18.3 DBCA UPPERCASING DB_UNIQUE_NAME FOR DIRECTORY OF DATA FILES AND CONTROL FILES.

進一步分析發現，我們將數據庫升級到19c，并將compatible由11.2.0.4改為19.3.0.0后，數據文件路徑就改為大寫了。

使用文件系統作為存儲介質的數據庫未出現此問題。

Directory for Datafiles and Controlfiles Become Uppercase in 18.3 DBCA. (Doc ID 2542927.1)

APPLIES TO:

Oracle Database Configuration Assistant - Version 18.3.0.0.0 and later
Information in this document applies to any platform.

SYMPTOMS

When you specified lowercase "DB_UNIQUE_NAME" variable(for example:orcl) in DB:18.3 DBCA to create DB instance
after the instance be created, you will find the directory of data files and control files contains uppercase DB_UNIQUE_NAME which you specified.
-----------------------------
/u01/app/oracle/oradata/ORCL
-----------------------------
This result is different from the previous version(DB:12.2/DB:12.1).

If we save the DBCA scripts which can be generated by DBCA, we could see that even if you specified lowercase DB_UNIQUE_NAME in DBCA, 
the script is to create uppercase DB_UNIQUE_NAME in the directory path of data files and control files.

CHANGES

Using DB:18.3 DBCA to create database instance and specified lowercase "DB_UNIQUE_NAME" variable.

CAUSE

It is a limitation according to current design.

SOLUTION

The following method can avoid this issue.

STEP 1: Generate the DBCA Scripts.
STEP 2: Change the uppercase DB_UNIQUE_NAME to lowercase DB_UNIQUE_NAME manually.
STEP 3: Execute these scripts to create DB instance.