15.00 - SysChangeThresholdOption - Teradata Database

Teradata Database Utilities

Product
Teradata Database
Release Number
15.00
Content Type
Configuration
Publication ID
B035-1102-015K
Language
English (United States)
Last Update
2018-09-25

SysChangeThresholdOption

Purpose  

Specifies whether Teradata Database should automatically determine an appropriate data change threshold for statistics recollection.

This setting is used only if the “DefaultUserChangeThreshold” setting is disabled (set to zero) when a COLLECT STATISTICS SQL statement does not specify the USING THRESHOLD PERCENT option.

Field Group

Optimizer Statistics

Settings

 

Value

Description

0

Use factory default, currently equivalent to setting 1.

1

Enables system-determined change threshold checking in statistics collection when DBQL ObjectUsage (update/delete/insert counts) is enabled.

2

Enables system-determined change threshold checking in statistics collection regardless of ObjectUsage setting in DBQL logging options.

3

Disables system-determined change threshold.

Default

0

Changes Take Effect

After the DBS Control Record has been written.

Usage Notes  

Statistics are used by the optimizer to improve query performance.

When cost profiles are in effect, this setting can be overridden by a cost profile constant value.

Related Topics

 

For more information on…

See…

Optimizer statistics fields

  • “DefaultTimeThreshold” on page 298
  • “DefaultUserChangeThreshold” on page 299
  • “SysSampleOption” on page 450
  • Cost profiles

  • DIAGNOSTIC SET PROFILE in SQL Data Manipulation Language
  • Target Level Emulation chapter in SQL Request and Transaction Processing