Analysis using a regular expression does not match the results of the regular expression tester

Products

Webtrends Analytics 9.x
Webtrends Analytics 8.x

Issue

A filter using a regular expression successfully passes the regular expression test, yet when the profile is analyzed, the report which should display data defined by the regular expression does not produce the expected results.

Resolution

The tester works using a method considered a “non-greedy match,” in which it is evaluated from right to left. The Webtrends analysis engine performs a “greedy match,” evaluating the entire expression in one pass. A properly crafted greedy statement will work in both cases, so the regular expression must be built as a greedy match to guarantee results.