-<!-- $PostgreSQL: pgsql/doc/src/sgml/func.sgml,v 1.384 2007/08/11 03:56:24 tgl Exp $ -->
+<!-- $PostgreSQL: pgsql/doc/src/sgml/func.sgml,v 1.385 2007/08/13 01:18:47 tgl Exp $ -->
<chapter id="functions">
<title>Functions and Operators</title>
</para>
<para>
- <productname>PostgreSQL</productname>'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
+ <function>regexp_matches</>, but is usually the most convenient behavior
+ in practice. Other software systems such as Perl use similar definitions.
</para>
<!-- derived from the re_syntax.n man page -->
<title>Regular Expression Details</title>
<para>
+ <productname>PostgreSQL</productname>'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.
+ </para>
+
+ <para>
Regular expressions (<acronym>RE</acronym>s), as defined in
<acronym>POSIX</acronym> 1003.2, come in two forms:
<firstterm>extended</> <acronym>RE</acronym>s or <acronym>ERE</>s