15.00 - Summary Optimizer Statistics Attributes - Teradata Database

Teradata Database SQL Data Definition Language Detailed Topics

Product
Teradata Database
Release Number
15.00
Content Type
Programming Reference
Publication ID
B035-1184-015K
Language
English (United States)

Summary Optimizer Statistics Attributes

The data types for the table attributes reported by a summary HELP STATISTICS request are as follows:

 

Attribute

Description

Data Type

Date

The date on which statistics were last collected.

CHARACTER(8) CHARACTER SET UNICODE

Time

The time at which statistics were last collected.

CHARACTER(8) CHARACTER SET UNICODE

Unique Values

An estimate of the number of unique values for the specified column set.

VARCHAR(20) CHARACTER SET UNICODE

Column Names

The names of the columns for which summary statistics are reported.

VARCHAR(2000)

The requirement of a 2,000 character maximum derives from the maximum number of columns per index and the maximum length of a column name plus overhead: (64 * 30) + 63 = 1983 characters.

On a standard language support system, the data type for Column Names is VARCHAR(2000) CHARACTER SET LATIN.

On a Japanese language support system, the data type for Column Names is VARCHAR(2000) CHARACTER SET UNICODE if a multibyte site-defined session character set such as UTF-8, UTF-16, Chinese, or Korean is used.

For any other language support system, the data type for Column Names is VARCHAR(2000) CHARACTER SET UNICODE.

The server character set for Column Names is Unicode, which gets translated to the client character set.

If there is multibyte character data, Column Names uses the UTF-8, UTF-16, or some other character sets that supports multibyte client character sets.

Related Topics

For information about collecting and dropping Optimizer statistics, see the following:

  • “COLLECT STATISTICS (Optimizer Form)” on page 175
  • “COLLECT STATISTICS (Optimizer Form)” in SQL Data Definition Language Syntax and Examples
  • “DROP STATISTICS (Optimizer Form)” on page 810
  • “DROP STATISTICS (Optimizer Form)” in SQL Data Definition Language Syntax and Examples
  • For information about reporting detailed Optimizer statistics, see the following.

  • “SHOW STATISTICS” on page 1002
  • “SHOW STATISTICS” in SQL Data Definition Language Syntax and Examples
  • Also see SQL Request and Transaction Processing and Database Design for information about statistics, their collection, and their recollection.