As discussed in the Tip of the Night for March 2, 2019, regular expressions can be used in repeated content filters to find disclaimers in the footers of email messages and other sentences which are repeated throughout a data set. These are removed from indexes in order to facilitate searching. Keep in mind that there are several different syntaxes of the regular expression language. Some of the most common are Perl; POSIX; the syntax used for the open source ViM ; and the regex syntax used with Python.

So for example while a Word boundary in a Perl, Python, and POSIX regex search is written as:

\b

in a ViM regex search it is:

/ \> OR /string\>

We may be familiar with using the pipe character | as an OR operator in Regex searches, but in POSIX (BRE) and ViM it is: \|

Relativity uses the Java.util.regex.Pattern Java RegEx syntax which is similar to Perl. Be sure to check to check your Regex searches with an online tester such as https://www.regextester.com/ in order to confirm that they will find examples of what you hope to match.

PCRE stands for Perl Compatible Regular Expressions.

This is the fourth anniversary of Tip of the Night - Four Years of Tips - every single night!