Commit e529cd4ffa605c6f introduced an Assert requiring NAMEDATALEN to be
less than MAX_LEVENSHTEIN_STRLEN, which has been 255 for a long time.
Since up to that instant we had always allowed NAMEDATALEN to be
substantially more than that, this was ill-advised.
It's debatable whether we need MAX_LEVENSHTEIN_STRLEN at all (versus
putting a CHECK_FOR_INTERRUPTS into the loop), or whether it has to be
so tight; but this patch takes the narrower approach of just not applying
the MAX_LEVENSHTEIN_STRLEN limit to calls from the parser.
Trusting the parser for this seems reasonable, first because the strings
are limited to NAMEDATALEN which is unlikely to be hugely more than 256,
and second because the maximum distance is tightly constrained by
MAX_FUZZY_DISTANCE (though we'd forgotten to make use of that limit in one
place). That means the cost is not really O(mn) but more like O(max(m,n)).
Relaxing the limit for user-supplied calls is left for future research;
given the lack of complaints to date, it doesn't seem very high priority.
In passing, fix confusion between lengths-in-bytes and lengths-in-chars
in comments and error messages.
Per gripe from Kevin Day; solution suggested by Robert Haas. Back-patch
to 9.5 where the unwanted restriction was introduced.
Commit 13629df changed metaphone() function to return an empty string on
empty input, but it left the old error message in place. It's now dead code.
Michael Paquier, per Coverity warning.
The hope is that we can use this to produce better diagnostics in
some cases.
Peter Geoghegan, reviewed by Michael Paquier, with some further
changes by me.
Because of gcc -Wmissing-prototypes, all functions in dynamically
loadable modules must have a separate prototype declaration. This is
meant to detect global functions that are not declared in header files,
but in cases where the function is called via dfmgr, this is redundant.
Besides filling up space with boilerplate, this is a frequent source of
compiler warnings in extension modules.
We can fix that by creating the function prototype as part of the
PG_FUNCTION_INFO_V1 macro, which such modules have to use anyway. That
makes the code of modules cleaner, because there is one less place where
the entry points have to be listed, and creates an additional check that
functions have the right prototype.
Remove now redundant prototypes from contrib and other modules.
Operating directly on the underlying varlena saves palloc and memcpy
overhead, which testing shows to be significant.
Extracted from a larger patch by Alexander Korotkov.
specify the cost values to use, instead of always using 1's.
Volkan Yazici
In passing, remove fuzzystrmatch.h, which contained a bunch of stuff that had
no business being in a .h file; fold it into its only user, fuzzystrmatch.c.
strings. This patch introduces four support functions cstring_to_text,
cstring_to_text_with_len, text_to_cstring, and text_to_cstring_buffer, and
two macros CStringGetTextDatum and TextDatumGetCString. A number of
existing macros that provided variants on these themes were removed.
Most of the places that need to make such conversions now require just one
function or macro call, in place of the multiple notational layers that used
to be needed. There are no longer any direct calls of textout or textin,
and we got most of the places that were using handmade conversions via
memcpy (there may be a few still lurking, though).
This commit doesn't make any serious effort to eliminate transient memory
leaks caused by detoasting toasted text objects before they reach
text_to_cstring. We changed PG_GETARG_TEXT_P to PG_GETARG_TEXT_PP in a few
places where it was easy, but much more could be done.
Brendan Jurd and Tom Lane
a few typos in comments.
The dictionaries I checked list "altho" as a variant of "although,"
but I didn't find any other instances of the former in the source
tree so I changed it.
Michael Fuhr
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
