Purpose - Teradata Director Program

Teradata® Director Program Reference - 17.20

Teradata Director Program
Release Number
June 2022
English (United States)
Last Update
Product Category
Teradata Tools and Utilities

Use the DISPLAY NP command to display information about one or more NPs that have been started or attached.

Because this command displays information about the status of an NP, the processing by an NP is briefly described as an aid to understanding. An optional ATTACH and a START command is issued for each NP. The START command either specifies an IP address or uses IP name information from the CONFIG NP command to locate the NP on the database, using network facilities provided by the operating system. This process is referred to by TDP as acquisition, but it does not actually communicate with the database. Once acquired, a TCP connection is established with the database, followed by a process between TDP and the database to initialize the encapsulation protocol. This protocol packages the request and response messages to and from the database in a form suitable for network transmission. Next is a process between TDP and the database to initialize the communication protocol. This protocol aggregates requests and responses to maximize throughput. Finally, TDP synchronizes its status of any existing sessions and requests with the database's status. Then normal network transmissions begin between TDP and the database. Requests are associated with an NP from the time they are sent until their responses are received. Should a communication problem occur, the encapsulation protocol is interrupted and must be re-established. Until this is done, the NP is idle. Depending on the problem, the communication protocol may also need to be re-established. The goal is to resume communication with the database. If at any time an unrecoverable error occurs, use of the NP is halted. The STOP and DETACH commands may be used to discontinue use of an NP. The processing is the reverse of starting the NP: normal network transmissions are quiesced, when they end the communication protocol is terminated, the encapsulation protocol is terminated, and TDP's use of the NP ends.

The communication protocol and synchronization between TDP and the database are the same for network and channel communication.