Downgrade procedure

This section describes how to downgrade from Adaptive Server 15.0 with encryption (Adaptive Server 15.0 EC) to an earlier version of Adaptive Server 15.0 without encryption

If you never configured encrypted columns on Adaptive Server, you do not need to do anything to prepare for downgrade.

If you have configured Adaptive Server to use encrypted columns, drop or decrypt the data in encrypted columns before you reload it on Adaptive Server 15.0 GA or Adaptive Server 15.0 ESD #1. If you do not do this, you will get errors or data corruption when you attempt to process the encrypted data in the earlier version of Adaptive Server 15.0.

To prepare the server for downgrade, remove decryption from all affected tables:

Start Adaptive Server in single-user mode to ensure that no other user can process encrypted columns while you remove encryption from the database.
Make sure sp_configure "enable encrypted columns" shows a Run Value of 1.
Run this command in each database in which the keys were created for a list of all encryption keys:
```
sp_encryption help
```
For each key listed in step 3, execute sp_encryption help, key_name, display_cols to generate a list of all columns this key encrypts. You must have the sso_role to run this command.

The result set includes the database name, table name, and column name for each column encrypted by key_name.

Or, run sp_help table_name on each table in each database. The column description indicates which columns are encrypted.
Either drop the tables that have encrypted columns or use alter table to decrypt the data. For example, to decrypt the column cc_no in the customer table, enter:
```
alter table customer modify cc_no decrypt
```
(Optional.) Drop all encryption keys. Dropping the keys ensures that you have removed all encryption from the database. Adaptive Server returns an error message if you attempt to drop a key that is associated with an existing encrypted column.
Drop the sp_encryption system procedure.
Disable the enable encrypted columns configuration option:
```
sp_configure "enable encrypted columns", 0
```
Shut down Adaptive Server.
Copy the RUN_SERVER file to $SYBASE/ASE-15_0/install in the earlier Adaptive Server 15.0 release area and modify it to use the dataserver binary from this release area.
Restart the server using the modified RUN_SERVER file.
Run the following scripts from the earlier Adaptive Server 15.0 release:
- installmaster – To return system procedures to their original version.
- installsecurity – If you enabled auditing.
- instmsgs.ebf – To make sure your Adaptive Server messages are at the correct level.
- installhasvss – If you enabled, and are using, high availability.
- installmsgsvss – If you have enabled, and are using, Adaptive Server messaging.

You cannot load any dumps of Adaptive Server 15.0 EC databases or transactions with encrypted columns into an earlier version of Adaptive Server 15.0.

Replication issues with downgrade

If you are downgrading a server that has replication enabled on databases that contain encrypted data, you must perform one of the following before you start the downgrade procedure:

Verify that you have successfully transferred all replicated data in the primary database transaction log to the standby or replicate database. The process for doing depends on the application you are using. See the documentation for your application for more information.

Truncate the transaction log in the primary database and set the RS locator to zero with this command:

sp_stop_rep_agent primary_dbname
dbcc settrunc ('ltm', 'ignore')
dump tran  primary_dbname with truncate_only
dbcc settruc ('ltm', 'valid')

Shutdown Replication Server. In the RSSD for the Replication Server run:

rs_zeroltm primary_servername, primary_dbname