Identifying Conditions That Can Be Optimized
In addition to containing key variables, WHERE conditions
must meet other requirements in order to be candidates for optimization.
SAS considers using an index only for WHERE conditions that contain
certain operators and functions. Therefore, the next step for SAS
is to consider the operators and functions in the conditions that
contain key variables.
Requirements for Optimizing a Single WHERE Condition
SAS considers using
an index for a WHERE condition that contains any of the following
operators and functions:
Note: For all of the following examples, assume that the data
set has simple indexes on the variables Quarter, Date_ID, and Region.
Operator
|
Example
|
---|---|
comparison operators
|
|
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