16.10 - Unity Data Dictionaries - Teradata Unity

Teradata Unity User Guide

Product
Teradata Unity
Release Number
16.10
Published
January 2018
Language
English (United States)
Last Update
2018-03-29
dita:mapPath
anz1496162519675.ditamap
dita:ditavalPath
ft:empty

For all managed routing sessions, Unity uses a data dictionary to determine the systems on which an object is available, and to apply locks to SQL statements.

Objects are added to the dictionary dynamically through DDL statements or via the Unity dictionary scanner. The dictionary scanner is capable of scanning large dictionaries; however, scan times are seriously affected by both the number of objects in the dictionary and the types of objects. Tables and views tend to be simple objects and Unity can scan more than 150,000 of this type of object per system.
Unity does not support more than 150,000 objects in managed dictionaries.
Stored procedures are complex and Unity must pull the original source from each system making these objects particularly slow in scanning. Triggers on tables similarly add complexity and increase scan times.

Any system-specific DDL are executed using a system-specific passive routing rule.

Macros are also unique in that source code must be included in dictionary deploy and this can cause slower deploys.

The scan time varies from several minutes to a few hours for a large system.

The scanner does not create a large load on systems. It is safe to run the scanner on an active system.

During the dictionary deploy, dynamic DDL updates to the dictionary are on hold. Live transactions that perform DDL are blocked until the deploy and dictionary load is complete. Dictionary deploy times vary from several minutes to a few hours.

To assist in object management, create a separate dictionary for each application you deploy. All dictionaries must be deployed at the same time. You cannot undeploy a dictionary once deployed.

Only one user may edit a dictionary at a time. When you edit a dictionary, a lock prevents other users from editing at the same time. The lock is released when you complete editing or if the user session remains idle for longer than the edit lock timeout. To change the duration of data dictionary editing locks, see Global Settings Tab.