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Concepts
What are database connections?
A database connection is a connection from a client application to a source of geographic data stored in a DBMS. 

To establish a connection, the application must provide the following information:

  • The name of the host server on which the geodatabase resides
  • The name of the service or direct connection syntax
  • The name of the database (not applicable for Oracle® databases)
  • The user name and password for authentication in the DBMS

ArcSDE processes the connection request on the specified host and returns a connection handle to the application once a connection is established. All operations performed using this connection are executed as the named user.

You can use operating system environment variables to define the server, instance, database, user name, and password. While supported, using the password variable is not recommended because it can compromise your security. Pass NULL for any argument for which the variable is set.


ArcSDE Services
API Comparison

  

The variables are:

  • SDESERVER—The name of the ArcSDE server
  • SDEINSTANCE—The name of the ArcSDE instance
  • SDEDATABASE—The name of the ArcSDE database (if required by the underlying DBMS)
  • SDEUSER—The user name
  • SDEPASSWORD—The user’s password

Connections in a multithreaded environment

By default, simultaneous access of a single ArcSDE connection by multiple threads is not supported. This guarantees the best performance when invoking methods on an established connection. To enforce a concurrency mechanism, which is required when building multithreaded applications, one of the concurrency schemes must be adopted. Please consult the Database Connections API in the API section to learn more about implementing the concurrent mechanism.
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