Per this discussion, here's a patch to implement both levenshtein() and

metaphone() in a contrib. There seem to be a fair number of different
approaches to both of these algorithms. I used the simplest case for
levenshtein which has a cost  of 1 for any character insertion, deletion, or
substitution. For metaphone, I adapted the same code from CPAN that the PHP
folks did.

A couple of questions:
1. Does it make sense to fold the soundex contrib together with this one?

2. I was debating trying to add multibyte support to levenshtein (it would
make no sense at all for metaphone), but a quick search through the contrib
directory found no hits on the word MULTIBYTE. Should worry about adding
multibyte support to levenshtein()?

Joe Conway

contrib/fuzzystrmatch/fuzzystrmatch.sql.in

@@ -0,0 +1,5 @@
+CREATE FUNCTION levenshtein (text,text) RETURNS int
+  AS 'MODULE_PATHNAME','levenshtein' LANGUAGE 'c' with (iscachable, isstrict);
+
+CREATE FUNCTION metaphone (text,int) RETURNS text
+  AS 'MODULE_PATHNAME','metaphone' LANGUAGE 'c' with (iscachable, isstrict);