compares two strings' soundex values for similarity, from Kris Jurka.
Also mark the text_soundex() function as STRICT, to avoid crashing
on NULL input.
an empty input string causes an empty output string to be returned, instead of
throwing an ERROR -- per complaint from Aaron Hillegass, and consistent with
double metaphone. Fix examples in README.soundex pointed out by James Robinson.
> Second argument to metaphone is suposed to set the limit on the
> number of characters to return, but it breaks on some phrases:
>
> usps=# select metaphone(a,3),metaphone(a,4),metaphone(a,20) from
> (select 'Hello world'::varchar AS a) a;
> HLW | HLWR | HLWRLT
>
> usps=# select metaphone(a,3),metaphone(a,4),metaphone(a,20) from
> (select 'A A COMEAUX MEMORIAL'::varchar AS a) a;
> AKM | AKMKS | AKMKSMMRL
>
> In every case I've found that does this, the 4th and 5th letters are
> always 'KS'.
Nice catch.
There was a bug in the original metaphone algorithm from CPAN. Patch
attached (while I was at it I updated my email address, changed the
copyright to PGDG, and removed an unnecessary palloc). Here's how it
looks now:
regression=# select metaphone(a,4) from (select 'A A COMEAUX
MEMORIAL'::varchar AS a) a;
metaphone
-----------
AKMK
(1 row)
regression=# select metaphone(a,5) from (select 'A A COMEAUX
MEMORIAL'::varchar AS a) a;
metaphone
-----------
AKMKS
(1 row)
Joe Conway
be able to apply against what you just committed. It rolls soundex into
fuzzystrmatch.
Remove soundex/metaphone and merge into fuzzystrmatch.
Joe Conway
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
