O'Reilly logo

SAS Certification Prep Guide, 4th Edition by SAS Institute

Stay ahead with the world's most comprehensive technology and business learning platform.

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, tutorials, and more.

Start Free Trial

No credit card required

Identifying Available Indexes

Overview

The first step for SAS is to determine whether there are any existing indexes that might be used to process the WHERE expression. Specifically, SAS checks the variable in each condition in the WHERE expression to determine whether the variable is a key variable in an index.
index on Order_Date
SAS can use either a simple index or a composite index to optimize a WHERE expression. To be considered for use in optimizing a single WHERE condition, one of the following requirements must be met:
  • the variable in the WHERE condition is the key variable in a simple index
  • the variable in the WHERE condition is the first key ...

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, interactive tutorials, and more.

Start Free Trial

No credit card required