A.2 Downgrading RDF Graph Support to a Previous Release

You can downgrade the RDF Graph support, in conjunction with an Oracle Database downgrade to Release 12.1.

However, downgrading is strongly discouraged, except for rare cases where it is necessary. If you downgrade to a previous release, you will not benefit from bug fixes and enhancements that have been made in intervening releases.

• Downgrading to Release 12.1 Semantic Graph Support
  

A.2.1 Downgrading to Release 12.1 Semantic Graph Support

If you need to downgrade to Oracle Database Release 12.1, the RDF semantic graph support component will be downgraded automatically when you downgrade the database. However, any RDF or OWL data that is specific to Release 12.2 (that is, Release 12.2 or later RDF/OWL persistent structures that are not supported in previous versions) must be dropped before you perform the downgrade, so that the database is compatible with Release 12.1.

To check if any Release 12.2 or later RDF data is incompatible with Release 12.1, perform the following steps:

1. Connect to the database (Release 12.2 or later) as the SYS user with SYSDBA privileges (SYS AS SYSDBA, and enter the SYS account password when prompted).

2. Start SQL*Plus, and enter the following statements:

   SET SERVEROUT ON
   EXECUTE SDO_SEM_DOWNGRADE.CHECK_121_COMPATIBLE;
   

If any RDF data is incompatible with Release 12.1, the procedure generates an error and displays a list of the incompatible data. In this case, you must perform the following steps:

1. Remove any Release 12.2 or later release-specific RDF or OWL data if you have not already done so, as explained earlier in this section.

2. Perform the database downgrade.

3. Connect to the Release 12.1 database as the SYS user with SYSDBA privileges (SYS AS SYSDBA, and enter the SYS account password when prompted).

4. Start SQL*Plus, and enter the following statement:

   • Linux: @$ORACLE_HOME/md/admin/catsem.sql

   • Windows: @%ORACLE_HOME%\md\admin\catsem.sql

     Note:

     If you are in a multitenant environment, run the script with catcon.pl. See “Running Oracle-Supplied SQL Scripts in a CDB” in Oracle Database Administrator’s Guide.

   If the script completes successfully, a row with the following column values is inserted into the MDSYS.RDF_PARAMETER table:

   • NAMESPACE: MDSYS

   • ATTRIBUTE: SEM_VERSION

   • VALUE: (string starting with 12.1)

   • DESCRIPTION: VALID

   After the catsem.sql script completes successfully, Oracle semantic technologies support for Release 11.2 is enabled and ready to use, and all Release 12.1-compatible data is preserved.