Passive Routing for Reporting and Other Read-Only Workloads | Teradata Business Continuity Manager - Passive Routing for Reporting and Other Read-Only Workloads - Teradata Business Continuity Manager

Teradata® Business Continuity Manager User Guide

Product
Teradata Business Continuity Manager
Release Number
1.0
Published
January 2022
Language
English (United States)
Last Update
2022-01-27
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B035-2550
lifecycle
previous
Product Category
Analytical Ecosystem

Passive routing enables a client session to connect to a single specified Teradata system. Requests are then sent to that system. Optionally, the routing rule can also define a set of failover servers so that if the first system is not available, the session reconnects to the next available system in the set.

Reporting applications and other workloads often use volatile tables for the temporary storage of selected data. This data is used only for the lifetime of the workload and is discarded when the workload completes. These types of workloads generally use a passive routing rule. The passive routing option provides the following benefits.
  • Volatile tables are only created on one system.
  • Queries that access the tables are sent only to the system.
  • With only one set of data generated (on a single system), it does not matter if the data generated is deterministic across multiple systems.
  • Requests from passive routing rules are never recorded in the recovery log, never affect the Business Continuity Manager data dictionary, or update the tdbcmgmt transaction table, processing time.

There are five types of passive routing rules.

Routing Rule Description
Single-System Specifies only a single system.

If that system is unavailable, the clients using this routing rule cannot connect. Use this option for users who do not require any failover capability or for DBAs who need to connect to a specific system to perform maintenance.

Preferred Specifies that the first system in the routing list is the preferred system.

If the system is unavailable, the session connects to the next available system in the routing rule system list.

Least Used Allows the client to connect to a set of two or more Teradata systems.

When the client connects, the requests are sent to the system with the least number of passive connections. Use this option to make sure the systems are evenly balanced when the sessions are running different loads.

Round Robin Allows the client to connect to a set of two or more Teradata systems.

When the client connects, requests are sent to the first system. The next session is sent to the second system, and so on. Use this option when each session is expected to run the same amount of work.

Weighted Round Robin Allows the client to connect to a set of two or more Teradata systems, but in a weighted ratio specified by the routing rule.

Use this option when working with systems that are sized differently and can support a different number of connected sessions.