Can an SAP application start on an Oracle database that is opened in read-only mode? Or does SAP need to modify any database-level tables when it starts the application? Also, can we use Oracle Database 10g flashback technology in an SAP Oracle environment? Does SAP support this?
See OSS NOTE 817253 -- FAQ: Open a database in read-only. The application directly performs changes to several database tables:
- Last logon time of users connecting
- Statistical information which is stored in the database
- ABAP loads are potentially generated
- Internal application server synchronization via table DDLOG
As such, using databases in read-only mode is not possible.
On Oracle Database 10g Flashback
Flashback Drop is a new feature in Oracle Database 10g. It is part of the Oracle Flashback technology.
If you delete a table (DROP TABLE), the table and the memory occupied by the table are not deleted immediately. The table is renamed in the Oracle Dictionary and logically transferred to the recycle bin. If you want to reverse the deletion of the table, you can recover it again from the recycle bin at a later point. this feature is called Flashback Drop. The memory occupied by the table is not deleted or overwritten until the space is needed in another segment. The design of the recycle bin prevents that database files keep growing due to delete operations.
As the SAP application, and especially SAP BW, systematically creates and deletes a large number of tables, the volume of the Oracle Dictionary may be bloated considerably as of Oracle Database 10g. In order to avoid this, you must deactivate this feature in the SAP environment.
This was first published in March 2009