Contents Index ESTIMATE function [Miscellaneous] EVENT_CONDITION function [System]

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ESTIMATE_SOURCE function [Miscellaneous]


Function 

Provides the source for selectivity estimates used by the query optimizer.

Syntax 

ESTIMATE_SOURCE (
column-name
[, value  [ , relation-string ] ] )

Parameters 

column-name    The name of the column that is being investigated.

value    The value to which the column is compared. This is optional.

relation-string    The comparison operator used for the comparison, enclosed in single quotes. The default is equality (=).

Return value 

The source of the selectivity estimate can be one of the following:

Standards and compatibility 
See also 

ESTIMATE function [Miscellaneous]

INDEX_ESTIMATE function [Miscellaneous]

Example 

The following statement returns the value Index, which means that the query optimizer probed an index to estimate the selectivity.

SELECT FIRST ESTIMATE_SOURCE( emp_id, 200, '>' )
FROM employee

Contents Index ESTIMATE function [Miscellaneous] EVENT_CONDITION function [System]