Vertica Analytics Platform Version 9.2.x Documentation

Regular Expression Functions

A regular expression lets you perform pattern matching on strings of characters. The regular expression syntax allows you to precisely define the pattern used to match strings, giving you much greater control than wildcard matching used in the LIKE predicate. The Vertica regular expression functions let you perform tasks such as determining if a string value matches a pattern, extracting a portion of a string that matches a pattern, or counting the number of times a pattern occurs within a string.

Vertica uses the Perl Compatible Regular Expression (PCRE) library to evaluate regular expressions. As its name implies, PCRE's regular expression syntax is compatible with the syntax used by the Perl 5 programming language. You can read PCRE's documentation about its library. However, if you are unfamiliar with using regular expressions, the Perl Regular Expressions Documentation is a good introduction.

The regular expression functions only operate on valid UTF-8 strings. If you try using a regular expression function on a string that is not valid UTF-8, the query fails with an error. To prevent an error from occurring, use the ISUTF8 function as an initial clause to ensure the strings you pass to the regular expression functions are valid UTF-8 strings. Alternatively, or you can use the 'b' argument to treat the strings as binary octets, rather than UTF-8 encoded strings.

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