UPDATE STATISTICS

Use the UPDATE STATISTICS statement to perform any of the following tasks:

Calculate the distribution of column values.
Update system catalog tables that the database server uses to optimize queries.
Force reoptimization of SPL routines.
Convert existing indexes when you upgrade the database server.

This statement is an extension to the ANSI/ISO standard for SQL.

Syntax

>>-UPDATE STATISTICS-------------------------------------------->
 
     .-LOW-.
>--+-+-----+--+----------------------------+--+--------------------+--------+-><
   |          '-| Table and Column Scope |-'  '-DROP DISTRIBUTIONS-'        |
   |                                                                   (1)  |
   +-+-MEDIUM-+--+----------------------------+--| RESOLUTION Clause |------+
   | '-HIGH---'  '-| Table and Column Scope |-'                             |
   |                        (2)                                             |
   '-| Routine Statistics |-------------------------------------------------'
 
Table and Column Scope:
 
|--FOR TABLE--+----------------------------------------------------------------+--|
              +-+-----------+-+-table---+-+------------------+-----------------+
              | '- 'owner.'-' '-synonym-' |    .-,------.    |                 |
              |                           |    V        |    |                 |
              |                           '-(----column-+--)-'                 |
              '-ONLY-- (--+-----------+--+-table---+-- )--+------------------+-'
                          '- 'owner.'-'  '-synonym-'      |    .-,------.    |
                                                          |    V        |    |
                                                          '-(----column-+--)-'

Notes:

See Resolution Clause
See Routine Statistics

Element	Description	Restrictions	Syntax
column	A column in table or synonym	Must exist. With MEDIUM or HIGH keywords, column cannot be of BYTE or TEXT data type	Identifier
synonym	Synonym for a table whose statistics are to be updated	The synonym and the table to which it points must exist in the current database	Database Object Name
table	Table for which statistics are to be updated	Must exist in the current database or be a temporary table created in the current session	Database Object Name

Usage

Use the UPDATE STATISTICS statement to update system catalog information that the query optimizer uses for operations on objects in the local database.

You cannot, however, update the statistics for a table or the query plan of a UDR that is external to the current database. That is, the database server ignores remote database objects when executing the UPDATE STATISTICS statement.