postgresql/contrib/metaphone/README.metaphone

This directory contains a module that implements the "Metaphone" code as
a PostgreSQL user-defined function.  The Metaphone system is a method of
matching similar sounding names (or any words) to the same code. 

Metaphone was invented by Lawrence Philips as an improvement to the popular
name-hashing routine, Soundex.

This metaphone code is from Michael Kuhn, and is detailed at
   http://aspell.sourceforge.net/metaphone/metaphone-kuhn.txt

Code for this (including this help file!) was liberally borrowed from
the soundex() module for PostgreSQL.

There are two functions:
  metaphone(text)       : returns hash of a name
  metaphone(text,int)   : returns hash (maximum length of int) of name

---

To install it, first configure the main source tree, then run make;
make install in this directory.  Finally, load the function definition
with psql:

    psql -f PREFIX/share/contrib/metaphone.sql

The following are some usage examples:

SELECT text_metaphone('hello world!');
SELECT text_metaphone('hello world!', 4);

CREATE TABLE s (nm text)\g

insert into s values ('john')\g
insert into s values ('joan')\g
insert into s values ('wobbly')\g

select * from s
where text_metaphone(nm) = text_metaphone('john')\g

select nm from s a, s b
where text_metaphone(a.nm) = text_metaphone(b.nm)
and a.oid <> b.oid\g

CREATE FUNCTION text_mp_eq(text, text) RETURNS bool AS
'select text_metaphone($1) = text_metaphone($2)'
LANGUAGE 'sql'\g

CREATE FUNCTION text_mp_lt(text,text) RETURNS bool AS
'select text_metaphone($1) < text_metaphone($2)'
LANGUAGE 'sql'\g

CREATE FUNCTION text_mp_gt(text,text) RETURNS bool AS
'select text_metaphone($1) > text_metaphone($2)'
LANGUAGE 'sql';

CREATE FUNCTION text_mp_le(text,text) RETURNS bool AS
'select text_metaphone($1) <= text_metaphone($2)'
LANGUAGE 'sql';

CREATE FUNCTION text_mp_ge(text,text) RETURNS bool AS
'select text_metaphone($1) >= text_metaphone($2)'
LANGUAGE 'sql';

CREATE FUNCTION text_mp_ne(text,text) RETURNS bool AS
'select text_metaphone($1) <> text_metaphone($2)'
LANGUAGE 'sql';

DROP OPERATOR #= (text,text)\g

CREATE OPERATOR #= (leftarg=text, rightarg=text, procedure=text_mp_eq,
commutator=text_mp_eq)\g

SELECT *
FROM s
WHERE text_mp_eq(nm,'pillsbury')\g

SELECT *
from s
where s.nm #= 'pillsbury';