Prior to ArcGIS 9.3, clients and geodatabases had to be maintained at the same release to be able to make a direct connection from the client to the geodatabase. Additionally, older clients could not connect to newer versions of the geodatabase with a direct connection or using an ArcSDE service (application server).
Beginning with ArcGIS 9.3, you can install files that will allow you to make a direct connection from any ArcGIS or ArcIMS 9.3 client to a 9.3, 9.2, 9.1, or 9.0 ArcSDE geodatabase. This allows you to use direct connections to the geodatabase without having to upgrade the geodatabase at the same time the clients are upgraded. The installation file for the necessary direct connect drivers is in the GDBDirectConnect folder on your installation media. On Windows, it can be executed from the installation dialog box and is called ArcGIS Pre 9.3 GDB Direct Connect drivers. You must run this installation to get the drivers.
ArcSDE application server connections are not affected by this; you are still able to connect from an ArcGIS 9.3 client to an older geodatabase using an ArcSDE application server, just as you always were.
In addition, files are available from the ESRI support site to allow you to connect from ArcGIS 9.2 service pack 5 (SP5) or later 9.2 SP release clients to ArcSDE 9.3 geodatabases using a direct connection. You will also be able to make an application server connection from ArcGIS 9.2 SP5 or later 9.2 SP clients to an ArcSDE geodatabase. No additional files are necessary to make the application server (ArcSDE service) connection from ArcGIS 9.2 SP5 or later service packs to an ArcSDE 9.3 geodatabase.
This topic covers some of the rules that apply to these interoperable connections.
To connect from an ArcGIS or ArcIMS 9.3 client to an ArcSDE 9.1 or 9.0 geodatabase, the geodatabase will have to be upgraded to the latest ArcSDE service pack or patch for 9.1 or 9.0.
Interoperable direct connections between client and geodatabase versions do not apply to ArcSDE for Informix due to differences in the client software development kit (SDK) necessary to make direct connections.
When you make a direct connection from a 9.3 client to an older ArcSDE geodatabase, you only have access to functionality that is available for the release of your geodatabase. For example, you cannot connect from an ArcGIS 9.3 client to an ArcSDE 9.1 geodatabase on Oracle and create a feature class using ST_Geometry storage because this storage type was not implemented in ArcSDE 9.1.
This also applies to C and Java API functionality; if the functionality does not exist in the version of the geodatabase to which you want to connect, you cannot use the newer C or Java API function. The reverse is also true; if an older function is no longer available in a newer release of the geodatabase, the older function cannot be called when executing against a newer release geodatabase.
Because support is no longer available from Oracle for Oracle8i databases, connections from 9.3 clients to ArcSDE 9.1 or 9.0 geodatabases stored in Oracle8i are not supported.
When you connect from an ArcGIS 9.2 SP5 or later release client to an ArcSDE 9.3 geodatabase with either a direct connection or an ArcSDE service, you do not have access to functionality that was newly implemented at 9.3. For example, you cannot connect from an ArcGIS 9.2 SP5 client to an ArcSDE 9.3 geodatabase on PostgreSQL or DB2 for z/OS. You also will not be able to use the Windows Size pyramid types for Terrains that are available in 3D Analyst for ArcGIS 9.3 or create a network dataset that uses Global Turn Delay or Network Function evaluators, which are available in Network Analyst for ArcGIS 9.3. Additionally, you will not be able to replicate from an ArcGIS 9.2 geodatabase to a file geodatabase. Similarly, you cannot connect to a 9.3 ArcSDE for SQL Server Express instance using a 9.2 SP5 client and create a geodatabase that has a full-text catalog.
When using ArcSDE for SQL Server Express, there is nothing to prevent a 9.2 SP5 or later service pack release client from connecting to an ArcSDE database server that is licensed for ArcGIS Server 9.3 Workgroup and creating a 9.2 geodatabase. The reverse is also true: a 9.3 client can connect to and create 9.3 geodatabases on a database server licensed for 9.2. If you have a mix of client releases at your organization, be aware that there is the potential to have different release geodatabases that, therefore, have different functionality on the same ArcSDE database server.
This also means there is the potential for connecting 9.3 clients to upgrade the geodatabases created by 9.2 clients. That may be acceptable for your workflow or it may not be—you need to decide the rules your users will follow in regard to this functionality. As always, users should create a backup of the geodatabase before upgrading it.
ArcGIS 9.2 SP5 or later service pack release clients should not detach 9.3 geodatabases. This has the potential to negatively affect the full-text catalog associated with the 9.3 geodatabase.