Team Exasol
Team Exasol

Background

Regular expressions do not recognize non-ascii national characters in class groups.

Example:

select regexp_substr('dejá vu', '[[:lower:]]+');
--> "dej"

Explanation

Character groups using [[:group:]] notation are Unicode-unaware as well as highly locale-dependant. Basically, they only work for the ASCII part of Unicode (characters 0 through 127).

As EXASolution implements the PCRE syntax for regular expressions, you should use Unicode character classes instead, using \p notation:

select regexp_substr('dejá vu', '[\p{Ll}]+');
--> "dejá"

Here, "Ll" denotes the property (L)etter, (l)owercase.

Additional References

A list of classes (or character properties) defined by the Unicode standard can be found in Table 12 of document http://www.unicode.org/reports/tr44/#Property_Values