New Features and Upgrading Guide
CHAPTER 5. Upgrading to Adaptive Server Anywhere
SQL Remote installations include a consolidated database and many remote databases, together with a Message Agent at each site.
At each site, the Message Agent handles the sending and receiving of messages. The messages take the form of SQL statements, and the database server handles the actual execution of those SQL statements.
The upgrade requirements for SQL Remote are as follows:
No need to upgrade databases There is no need to upgrade databases for Version 6. However, if you do wish to upgrade a database, you can do so using the Upgrade utility at any of the sites. There is no need for all databases to be upgraded at the same time.
Software upgrades can be one site at a time Version 5 Message Agents can exchange messages with Version 6 Message Agents as long as the COMPRESSION database option is set to a value of -1 (minus one). There is no need to upgrade software throughout the installation simultaneously.
Message Agent and server can be upgraded separately The Message Agent is an Embedded SQL application. Therefore, the database server can be upgraded before the Message Agent as long as the compatibility library is used. It is, however, recommended that you upgrade your Message Agent at the same time as the database server for performance reasons.
The Message Agent cannot be upgraded before the database server, as a Version 6 client application cannot work with a Version 5 server.
Do not unload and reload There is no need to unload and reload a database when moving from Version 5 to Version 6.
Replication is based on the transaction log, and when a database is unloaded and reloaded, the old transaction log is no longer available. For this reason, good backup practices are especially important when participating in replication.
One approach to upgrading is as follows:
Upgrade the consolidated database server and Message Agent. Set the COMPRESSION database option to -1 so that all messages are compatible with the Version 5 software at remote sites.
Over time, upgrade remote database servers and Message Agents. You can set the COMPRESSION database option to a value other than -1 to take advantage of compression and encoding on messages being sent to the consolidated database server.
When all remote database servers and Message Agents are upgraded, set the COMPRESSION database option a the consolidated site to a value other than -1.