16.10 - Read/Write Requests for Passive Routing - Teradata Unity

Teradata Unity User Guide

Teradata Unity
Release Number
January 2018
English (United States)
Last Update

Passive sessions are opened on only one system, per routing rule definition. All Reads and Writes are directed to that system. If a request contains Writes to one or more objects, the objects are compared with the objects in the Data Dictionary. If a Write object exist in the Data Dictionary and the session's associated routing rule does not allow Writes to managed objects, the query is rejected with error code 4530, "Query rejected because associated routing rule prohibits writing to managed objects."

For Writes, since there is only one system, Unity does not perform data consistency checks or keep Writes to managed objects in sync. When a Read or allowed Write is done against a Unity managed object (object exists in Data Dictionary), access to the object is allowed regardless of the state of the objects. This allows passive sessions (sessions associated with a Passive routing rule) to access objects that are Unrecoverable or in an otherwise inaccessible state in the Data Dictionary.