17.10 - Usage Notes - Advanced SQL Engine - Teradata Database

Teradata Vantage™ - Database Utilities

Product
Advanced SQL Engine
Teradata Database
Release Number
17.10
Release Date
July 2021
Content Type
Configuration
Publication ID
B035-1102-171K
Language
English (United States)

User Names

By default, Gateway Global treats user names as ISO 8859-1 (Latin-1) encoding. Characters that cannot be represented in 7-bit ASCII, or that are non-printable are represented using the Unicode delimited identifier format.

User names that contain no characters that would require the use of Unicode delimited identifier syntax, but that contain characters that would require quoting in SQL (such as names containing a space character), can be represented by simple double-quote character (“) delimited identifiers, for example “john doe”. Unicode delimited identifiers and identifiers enclosed in double quotation marks are described in Teradata Vantage™ - SQL Fundamentals, B035-1141.

Client Disconnections and Reconnections

Client sessions that are disconnected from the gateway due to communications failures can immediately reconnect.

During the reconnection, both the old lost connection and new reconnecting connection can briefly appear simultaneously, having the same session number in the output of Gateway Global commands DISPLAY GTW, DISPLAY USER, and DISPLAY STATS USER.

You can distinguish the old from the new connection by looking at the status displayed in the output: The new connection shows a status of REASSIGN, TAKEOVER, or EXITED, while the old connection shows a status of TAKENOVER or LOGOFF for the DISPLAY GTW and DISPLAY USER commands, or just the requested statistics for the DISPLAY STATS USER command.

Gateway Status

Gateway Global commands DISPLAY GTWand DISPLAY USER report gateway status information, which appears as a column in the output. For disconnected sessions, status is additionally shown in the output of the DISPLAY SESSION and DISPLAY STATS USER commands.

The following table lists and briefly describes these statuses.

Status Description Persistence
CONNECTED Session is connected to the gateway. While session is connected.
DISCON The connection for a session was lost. Gateway is waiting for reconnection. Until the client reconnects or until the session is logged off after the session timeout period, which can be specified using the gtwcontrol -t command. For more information on gtwcontrol, see Gateway Control (gtwcontrol).
EXITED The reconnecting connection has done an implicit logoff (an orderly close of its connection) after having authenticated itself, but before the old connection has completed its takeover processing. The session will be logged off after the takeover processing is complete. Brief, rarely seen.
FORCED Session has been forced to close by Gateway Global, Performance Monitoring or Production Control (PMPC), or by a security violation. Session timeout period, which can be specified using the gtwcontrol -t command. For more information on gtwcontrol, see Gateway Control (gtwcontrol).
GONE Session forced off by PMPC. Session timeout period, which can be specified using the gtwcontrol -t command. For more information on gtwcontrol, see Gateway Control (gtwcontrol).
KILLED Session has been killed by the Gateway Global KILL SESSION or KILL USER command. Until logoff is confirmed. Brief, rarely seen.
LOGOFF Reported for a session while it is being logged off due to an earlier implicit logoff (an orderly close of its connection) by a new connection that was taking over the session. From the time the session completes its takeover processing and begins logging off until the logoff is complete.
REASSIGN Reported for a new connection when it has requested that an existing session be reassigned to it, but it hasn't yet established the right to take over the session. Between when a reconnection attempt starts and the time it authenticates itself and is allowed to take over for a lost connection. Brief, rarely seen.
TAKENOVER Reported for the original (disconnected) connection while the session is in the process of being taken over by a new connection during an authenticated reconnect. Until the original connection completes takeover processing or the session is logged off. Brief, rarely seen.
TAKEOVER Reported for an authenticated new connection while it's taking over an existing session from its original (disconnected) connection Until the original connection completes takeover processing, the session is logged off, or the new connection does an implicit logoff or disconnects. Brief, rarely seen.