Priority Scheduler - Teradata Database

Priority Scheduler

Priority Scheduler is a resource management tool that controls the dispersal of computer resources in Teradata Database. This resource management tool uses scheduler parameters that satisfy site-specific requirements and system parameters that depict the current activity level of Teradata Database. You can provide Priority Scheduler parameters to directly define a strategy for controlling computer resources.

You can use Priority Scheduler to:

Define a weighting system, based on user logon characteristics or Workload Definition (WD) rules, which prioritizes the database workload.

To define scheduling parameters and to monitor your current system activity.

Note: If TASM workload definition (Category 3) is active, no Priority Scheduler modifications are allowed through schmon.

Design Goals

Priority Scheduler includes default parameters that provide four priority levels; all users are assigned to one level.

To take advantage of Priority Scheduler capabilities:

Assign users to one of the several default priority levels based on a priority strategy.

Define additional priority levels and assign users to them to provide a more sophisticated priority strategy.

Assign user who execute very response-sensitive work to a very high priority level to support Teradata Database applications.

For a description of the structure of and relationships between the scheduling components and parameters of Priority Scheduler, see “Priority Scheduler” in Utilities.

When setting up for Priority Scheduler, Teradata recommends:

A low number of active AGs are preferred. 5 or 6 is a good target.

1 or 2 Resource Partitions (RPs) to cover all user work.

A reasonably higher weight assigned to tactical query components, compared to those supporting other user work.

A demotion AG, if needed.

One possible RP setup is the following.

RP	Weight	Description
Default	40	Console utilities
Tactical (optional)	40	Highly-tuned tactical queries only
Standard	20	All nontactical user-assigned work

The recommended setup assumes that tactical queries are highly tuned and that they demonstrate the following characteristics: that all-AMP queries consume low levels of CPU per node.

Bringing together all PGs doing nontactical work into a single RP makes it:

Easier to understand priority differences among AGs.

Simpler to setup and tune.

Less complex when faced with growth.

Easier when several PGs to share a single AG.