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
Bruce Momjian
Neil Conway
Tom Lane
Joe Conway