Oracle8 Server Migration Release 8.0 A54650_01

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Downgrading from Oracle8

This chapter discusses downgrading an Oracle8, Release 8.0.3 database to Oracle7, Release 7.x. The following topics are addressed:

• Use of the Migration Utility
• Downgrading Oracle8 to Release 7.x

Use of the Migration Utility

Oracle does not support downgrading from Oracle8 to Oracle7 using the Oracle8 Migration Utility, and Oracle8 provides no other facilities expressly for such downgrading. However, you can use Export/Import or data copying to move data from Oracle8 to Oracle7, as described in the next section.

Downgrading Oracle8 to Release 7.x

An Oracle8 database can be returned (downgraded) to a previous (Oracle7) database, for example, to a Release 7.3 database. However, few downgrade pathways are available for such a downgrade, and the necessary procedures may require extra time and effort:

If the Oracle8 database contains no new data that needs to be preserved, simply restore the complete backup of the previous Release 7.x source database and open it again. Be certain that the restore includes the initialization parameters that were used in the previous Release 7.x database.

If the Oracle8 database does contain new data that needs to be preserved, proceed as follows:

• Use Oracle 7 Export (with the CATEXP7.SQL-created views installed) to export the part of the Oracle8 database containing the new data. For more information on performing an Oracle7 Export from Oracle8, see Oracle8 Server Utilities.
• Restore the complete backup of the previous Oracle7 database (making sure the restore includes the previous initialization parameters) and open the restored database.
• Into the restored Oracle7 database, use Oracle7 Import to import the file previously exported from the Oracle8 database.

Several other methods are available for sending table data from the Oracle8 database back to the Oracle7 (source) database. These methods of returning data to Oracle7 are relatively simple if only a few tables have been updated using Oracle8. However, copying an entire database of tables can be a long and complicated task, so you should decide whether you need to return to Oracle7 before you update many tables using Oracle8.

• You can use SQL*Plus to create non-Oracle text files from the new Oracle8 data and then use the SQL*Loader to load the data back into the Oracle7 database.
• You can use the SQL*Plus COPY command to copy the new data from the Oracle8 database tables into the tables in the earlier Oracle7 database. For more information on the COPY command, see the SQL*Plus User's Guide and Reference.
• If you are still running the earlier Oracle7 database, you can re-create the table where data has been added or modified (using CREATE TABLE ... AS SELECT) by selecting the data in the Oracle8 database table through a distributed query from that Oracle7 database using a database link. For more information on the AS clause of the CREATE TABLE command, see Oracle8 Server SQL Reference.

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