What's the usage of Oracle directories in Replicate Oracle source?
While Replicate working with Oracle source database, some questions are raised for example:
- Purpose for creation of directories in Oracle (Source)
- What are files we are going to keep in these directories
- What storage required for the directories
- If files are going to keep in the directories then what will be the retention period
This article address these basic questions.
Explanations
Oracle provides functionality called "Directories" which is a secure and robust capability to access operating system directories and files. A DIRECTORY object specifies a logical alias name for a physical directory on the database server file system under which the file to be accessed is located, Oracle directory pointing to a operating system directory on the database server machine for reading and writing files.
You can use the Oracle Directories to read/write 'files' (and LOBs) via your script, apps, or any software. It's same for Replicate, while Replicate reads the Oracle Redo Log files (for both Online and archived redo), we use the logical alias name too, that why we need to create the directories in Oracle source DB when using Replicate Log Reader access Oracle source DB.
Please take note that Directories do not allow subdirectory traversal. That means that you need to create Oracle directories for all directories and subdirectories you need to access.
In summary, Oracle directories is total different thing with OS level directories. It's *NOT* used to 'store' something so you need not allocate spaces or reserve spaces for it. Certainly you need not to care about the retention of it.
Reference documents Oracle CREATE DIRECTORY
Qlik article Why does Replicate perform 'create directory'
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