Download (direct link):
A session is explicitly logged on and off from the Teradata RDBMS. The session is established when the Teradata server accepts the logon string of the user. When a session is logged off, the system discards the user-session identification and does not accept additional Teradata SQL statements from that session.
To access the Teradata database from a mainframe client, the user or application program logs on through a Teradata interface facility (such as BTEQ) and submits a request. The request is processed by the interface and directed to a Teradata Director Program (TDP).
Each request is handled as follows:
• In a channel environment, the TDP builds the request parcel and sends it through the channel to the PE associated with that TDP.
• In a network environment, the MTDP builds the request parcel and sends it over the network to the Teradata gateway. The gateway distributes the parcel to an available PE on the node on which the gateway is running.
The result of a query or a status becomes the returned answer set. The PE turns the answer set into a response parcel and returns it to:
• The TDP, in a channel environment. The TDP returns it to the client utility or program.
• The gateway, in a network environment. The gateway sends it to the MTDP, and the MTDP returns it to the client utility or program.
Controlling Session Defaults
You can control session defaults by including the DEFAULT DATABASE, COLLATION, and/or ROLE options in the CREATE USER or MODIFY USER statement, or by issuing a SET statement during a session. DR52715
You can also control session conditions for particular users by defining a STARTUP clause containing a string of one or more Teradata SQL statements. A STARTUP string is subject to the same restrictions as a macro.
Teradata RDBMS Database Administration
A - 21Appendix A: Teradata RDBMS Configuration, Global Defaults, and Client Connections
Communicating with Teradata RDBMS
Client-Server Applications Connectivity
Applications performing embedded SQL statements need to pre-processed by the Teradata Preprocessor2, which runs on a client system.
You can run the preprocessor against an application without connecting to the Teradata RDBMS if you specify the SQLCHECK (-sc) option as NOSYNTAX. However, to precompile and run an application, a separate connection to Teradata RDBMS is required for the precompilation and the runtime event.
Also offered is a client utility, the Data Definition Language Processor (DDLP), that processes ANSI data definition language statements for Teradata RDBMS for UNIX. This processor breaks down entry level ANSI SQL CREATE SCHEMA statements into their individual components and sends requests to the Teradata RDBMS to create databases, tables, views, and user privileges. DDLP commands can be entered from a workstation, terminal, or command file.
DDLP is only supported with the Teradata RDBMS for UNIX, Version 2 Release 2.0, or higher. DDLP runs only on NCR platforms with UNIX SVR4 MP-RAS 3.00.02, or higher. The DDLP interacts with the Teradata RDBMS through the Teradata RDBMS call-level interface version 2 (CLIv2).
For instructions on how to prepare, precompile, and run an application on Teradata RDBMS with embedded SQL statements, see Teradata RDBMS SQL Reference, Volume 4 and Teradata Preprocessor2 Programming Guide.
For details on using DDLP and CLIv2, see:
• Teradata Data Definition Language Processor Reference
• Teradata Enhanced Call-Level Interface Reference
• Teradata Call-Level Interface Version 2 Reference for Channel-Attached Systems
• Teradata Call-Level Interface Version 2 Reference for Network-Attached Systems
A - 22
Teradata RDBMS Database Administration A - 21Appendix A: Teradata RDBMS Configuration, Global Defaults, and Client Connections
Teradata utilities and software programs support Teradata database access in mainframe environments. These utilities and programs run under the client's operating system and provide the functionality for a user to access the database system.
The Teradata Channel Interface enables communication between a mainframe client and a Teradata server using a channel with either a parallel or serial I/O interface. Two devices that consist of an even and odd address pair make up this connection. Each device is independent of the other. The client sends Teradata RDBMS messages to a server using the device with the even address. The server returns responses to the client using the device with the odd address.
This hardware was originally known as the Channel Interface Controller (CIC). Each CIC was associated with one Teradata Interface Processor (IFP) to provide a device pair on a parallel I/O interface channel, or with the MicroChannel-to-Channel Adapter (MCCA) board Application Processor (AP) and a Parsing Engine (PE).
The current platforms can be connected with either traditional Bus and Tag or the new ESCON fiber channel. The Host Channel Adapters available on WorldMark systems are: