The following topics introduce the PSQL Distributed Tuning Interface:

You can also go directly to Distributed Tuning Interface Reference for detailed information on the use of DTI in PSQL.

The purpose of Distributed Tuning Interface (DTI) is to provide an application programming interface for configuration, monitoring, and diagnostics of PSQL components.

A user application uses the client’s OS encoding at the API level. DTI handles internally the differences between OS encodings on the server and client.

If an older client is communicating with the server, the database engine assumes that the client is using an encoding compatible with those available on the server.

The categories of available APIs are summarized in Table 2, DTI Function Groups.

Generally, you want your DTI application to be able to call any of the DTI functions and view or modify all configuration settings. To ensure this full access, connect to the server by providing a name and password of a user with administrative level privileges on the server machine. This applies if the DTI application is running locally through a Terminal Services session or running remotely. An application running locally can omit the user name and password and still be able call any of the DTI functions and view or modify all configuration settings. See Making a Connection to a Server Using DTI.

Without administrator level privileges, an application running locally through a Terminal Services session or running remotely returns an access error for most of the DTI functions. Only a subset of the functions work. For example, many of the functions that can modify configuration settings when full access is permitted are restricted to read-only access.

The DTI functions are defined in the following header files:

The following table lists the link libraries for DTI and the PSQL version in which the library was first available. Link your application to the appropriate library as defined in the table.

The functions for the DTI are documented in Distributed Tuning Interface Reference.

When you want to invoke DTI, you must first call the PvStart() function. Then you can call multiple DTI functions before ending the session.

When ending a session, you must call PvStop() to close the session.

By default, the runtime files for the DTI access method are installed with the PSQL database engine and with PSQL Client. At a minimum, you need PSQL Client to create a DTI application.

The header files and sample files are available by online download. Sample files pertaining to a particular development environment are installed in separate directories, as shown in the following table.

For additional information, see the DTI release notes (readme_dti.htm) installed with the PSQL database engine.

This section outlines key tasks that are often used with DTI.

This documents the procedure for obtaining a connection handle to a server, which is a first step for many DTI functions.

Connection handles are required by many DTI functions. You can have multiple connections open at a time. For each connection or handle, however, you should call the PvDisconnect() function to release the handle.

Many of the configuration functions take a setting ID as a parameter. This procedure describes the prerequisite functions for obtaining a setting ID.

Many functions require that you pass a DTI structure when making the functional call. The following code segment shows an example of a function call including a structure. See DTI Structures for more information about DTI structures.