diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml index 4e5f8f1148a..52858efc600 100644 --- a/doc/src/sgml/func.sgml +++ b/doc/src/sgml/func.sgml @@ -1,4 +1,4 @@ - + Functions and Operators @@ -3383,10 +3383,12 @@ SELECT foo FROM regexp_split_to_table('the quick brown fox', E'\\s*') AS foo; - PostgreSQL's regular expressions are implemented - using a package written by Henry Spencer. Much of - the description of regular expressions below is copied verbatim from his - manual entry. + As the last example demonstrates, the regexp split functions ignore + zero-length matches that occur at the start or end of the string + or immediately after a previous match. This is contrary to the strict + definition of regexp matching that is implemented by + regexp_matches, but is usually the most convenient behavior + in practice. Other software systems such as Perl use similar definitions. @@ -3394,6 +3396,13 @@ SELECT foo FROM regexp_split_to_table('the quick brown fox', E'\\s*') AS foo; Regular Expression Details + + PostgreSQL's regular expressions are implemented + using a package written by Henry Spencer. Much of + the description of regular expressions below is copied verbatim from his + manual entry. + + Regular expressions (REs), as defined in POSIX 1003.2, come in two forms: