Add a variant of the Levenshtein string-distance function that lets the user
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.
This commit is contained in:
Tom Lane
parent
bbe48195ab
commit
55f6e5f689
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@ -5,7 +5,7 @@
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*
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* Joe Conway <mail@joeconway.com>
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*
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* $PostgreSQL: pgsql/contrib/fuzzystrmatch/fuzzystrmatch.c,v 1.26 2008/03/25 22:42:41 tgl Exp $
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* $PostgreSQL: pgsql/contrib/fuzzystrmatch/fuzzystrmatch.c,v 1.27 2008/04/03 21:13:07 tgl Exp $
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* Copyright (c) 2001-2008, PostgreSQL Global Development Group
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* ALL RIGHTS RESERVED;
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*
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@ -15,6 +15,8 @@
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* found at http://www.merriampark.com/ld.htm
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* Also looked at levenshtein.c in the PHP 4.0.6 distribution for
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* inspiration.
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* Configurable penalty costs extension is introduced by Volkan
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* YAZICI <volkan.yazici@gmail.com>.
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*
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* metaphone()
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* -----------
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@ -43,153 +45,251 @@
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*
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*/
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#include "fuzzystrmatch.h"
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#include "postgres.h"
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#include <ctype.h>
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#include "fmgr.h"
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#include "utils/builtins.h"
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PG_MODULE_MAGIC;
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/*
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* Calculates Levenshtein Distance between two strings.
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* Uses simplest and fastest cost model only, i.e. assumes a cost of 1 for
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* each deletion, substitution, or insertion.
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* External declarations for exported functions
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*/
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PG_FUNCTION_INFO_V1(levenshtein);
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Datum
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levenshtein(PG_FUNCTION_ARGS)
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extern Datum levenshtein_with_costs(PG_FUNCTION_ARGS);
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extern Datum levenshtein(PG_FUNCTION_ARGS);
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extern Datum metaphone(PG_FUNCTION_ARGS);
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extern Datum soundex(PG_FUNCTION_ARGS);
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extern Datum difference(PG_FUNCTION_ARGS);
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/*
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* Soundex
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*/
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static void _soundex(const char *instr, char *outstr);
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#define SOUNDEX_LEN 4
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/* ABCDEFGHIJKLMNOPQRSTUVWXYZ */
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static const char *soundex_table = "01230120022455012623010202";
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#define soundex_code(letter) soundex_table[toupper((unsigned char) (letter)) - 'A']
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/*
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* Levenshtein
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*/
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#define MAX_LEVENSHTEIN_STRLEN 255
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static int levenshtein_internal(const char *s, const char *t,
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int ins_c, int del_c, int sub_c);
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/*
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* Metaphone
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*/
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#define MAX_METAPHONE_STRLEN 255
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/*
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* Original code by Michael G Schwern starts here.
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* Code slightly modified for use as PostgreSQL function.
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*/
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/**************************************************************************
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metaphone -- Breaks english phrases down into their phonemes.
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Input
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word -- An english word to be phonized
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max_phonemes -- How many phonemes to calculate. If 0, then it
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will phonize the entire phrase.
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phoned_word -- The final phonized word. (We'll allocate the
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memory.)
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Output
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error -- A simple error flag, returns TRUE or FALSE
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NOTES: ALL non-alpha characters are ignored, this includes whitespace,
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although non-alpha characters will break up phonemes.
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****************************************************************************/
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/**************************************************************************
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my constants -- constants I like
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Probably redundant.
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***************************************************************************/
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#define META_ERROR FALSE
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#define META_SUCCESS TRUE
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#define META_FAILURE FALSE
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/* I add modifications to the traditional metaphone algorithm that you
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might find in books. Define this if you want metaphone to behave
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traditionally */
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#undef USE_TRADITIONAL_METAPHONE
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/* Special encodings */
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#define SH 'X'
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#define TH '0'
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static char Lookahead(char *word, int how_far);
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static int _metaphone(char *word, int max_phonemes, char **phoned_word);
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/* Metachar.h ... little bits about characters for metaphone */
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/*-- Character encoding array & accessing macros --*/
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/* Stolen directly out of the book... */
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char _codes[26] = {
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1, 16, 4, 16, 9, 2, 4, 16, 9, 2, 0, 2, 2, 2, 1, 4, 0, 2, 4, 4, 1, 0, 0, 0, 8, 0
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/* a b c d e f g h i j k l m n o p q r s t u v w x y z */
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};
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#define ENCODE(c) (isalpha((unsigned char) (c)) ? _codes[((toupper((unsigned char) (c))) - 'A')] : 0)
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#define isvowel(c) (ENCODE(c) & 1) /* AEIOU */
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/* These letters are passed through unchanged */
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#define NOCHANGE(c) (ENCODE(c) & 2) /* FJMNR */
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/* These form dipthongs when preceding H */
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#define AFFECTH(c) (ENCODE(c) & 4) /* CGPST */
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/* These make C and G soft */
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#define MAKESOFT(c) (ENCODE(c) & 8) /* EIY */
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/* These prevent GH from becoming F */
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#define NOGHTOF(c) (ENCODE(c) & 16) /* BDH */
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/*
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* levenshtein_internal - Calculates Levenshtein distance metric
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* between supplied strings. Generally
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* (1, 1, 1) penalty costs suffices common
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* cases, but your mileage may vary.
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*/
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static int
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levenshtein_internal(const char *s, const char *t,
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int ins_c, int del_c, int sub_c)
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{
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char *str_s = TextDatumGetCString(PG_GETARG_DATUM(0));
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char *str_t = TextDatumGetCString(PG_GETARG_DATUM(1));
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int cols = strlen(str_s) + 1;
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int rows = strlen(str_t) + 1;
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char *str_s0;
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int *u_cells;
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int *l_cells;
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int *tmp;
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int i;
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int j;
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int m, n;
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int *prev;
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int *curr;
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int i, j;
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const char *x;
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const char *y;
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m = strlen(s);
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n = strlen(t);
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/*
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* str_s is referred to as the "source", str_t is referred to as the
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* "target", cols = length of source + 1 to allow for the initialization
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* column, rows = length of target + 1 to allow for the initialization row
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* If either m or n is 0, the answer is the other value. This makes
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* sense since it would take that many insertions to build a matching
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* string
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*/
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if (!m)
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return n;
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if (!n)
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return m;
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/*
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* Restrict the length of the strings being compared to something
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* reasonable because we will have to perform rows * cols calculations. If
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* longer strings need to be compared, increase MAX_LEVENSHTEIN_STRLEN to
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* suit (but within your tolerance for speed and memory usage).
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* For security concerns, restrict excessive CPU+RAM usage. (This
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* implementation uses O(m) memory and has O(mn) complexity.)
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*/
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if ((cols > MAX_LEVENSHTEIN_STRLEN + 1) || (rows > MAX_LEVENSHTEIN_STRLEN + 1))
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if (m > MAX_LEVENSHTEIN_STRLEN ||
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n > MAX_LEVENSHTEIN_STRLEN)
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ereport(ERROR,
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(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
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errmsg("argument exceeds the maximum length of %d bytes",
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MAX_LEVENSHTEIN_STRLEN)));
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/*
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* If either rows or cols is 0, the answer is the other value. This makes
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* sense since it would take that many insertions the build a matching
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* string
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*/
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if (cols == 0)
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PG_RETURN_INT32(rows);
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if (rows == 0)
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PG_RETURN_INT32(cols);
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/* One more cell for initialization column and row. */
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++m;
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++n;
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/*
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* Allocate two vectors of integers. One will be used for the "upper" row,
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* the other for the "lower" row. Initialize the "upper" row to 0..cols
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* Instead of building an (m+1)x(n+1) array, we'll use two
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* different arrays of size m+1 for storing accumulated values.
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* At each step one represents the "previous" row and one is the
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* "current" row of the notional large array.
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*/
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u_cells = palloc(sizeof(int) * cols);
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for (i = 0; i < cols; i++)
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u_cells[i] = i;
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prev = (int *) palloc(2 * m * sizeof(int));
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curr = prev + m;
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l_cells = palloc(sizeof(int) * cols);
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/* Initialize the "previous" row to 0..cols */
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for (i = 0; i < m; i++)
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prev[i] = i;
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/*
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* Use str_s0 to "rewind" the pointer to str_s in the nested for loop
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* below
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*/
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str_s0 = str_s;
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/*
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* Loop through the rows, starting at row 1. Row 0 is used for the initial
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* "upper" row.
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*/
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for (j = 1; j < rows; j++)
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/* Loop through rows of the notional array */
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for (y = t, j = 1; j < n; y++, j++)
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{
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int *temp;
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/*
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* We'll always start with col 1, and initialize lower row col 0 to j
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* First cell must increment sequentially, as we're on the
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* j'th row of the (m+1)x(n+1) array.
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*/
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l_cells[0] = j;
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for (i = 1; i < cols; i++)
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curr[0] = j;
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for (x = s, i = 1; i < m; x++, i++)
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{
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int c = 0;
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int c1 = 0;
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int c2 = 0;
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int c3 = 0;
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int ins;
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int del;
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int sub;
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/*
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* The "cost" value is 0 if the character at the current col
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* position in the source string, matches the character at the
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* current row position in the target string; cost is 1 otherwise.
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*/
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c = (*str_s != *str_t);
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/* Calculate costs for probable operations. */
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ins = prev[i] + ins_c; /* Insertion */
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del = curr[i-1] + del_c; /* Deletion */
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sub = prev[i-1] + ((*x == *y) ? 0 : sub_c); /* Substitution */
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/*
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* c1 is upper right cell plus 1
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*/
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c1 = u_cells[i] + 1;
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/*
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* c2 is lower left cell plus 1
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*/
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c2 = l_cells[i - 1] + 1;
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/*
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* c3 is cell diagonally above to the left plus "cost"
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*/
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c3 = u_cells[i - 1] + c;
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/*
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* The lower right cell is set to the minimum of c1, c2, c3
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*/
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l_cells[i] = (c1 < c2 ? c1 : c2) < c3 ? (c1 < c2 ? c1 : c2) : c3;
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/*
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* Increment the pointer to str_s
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*/
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str_s++;
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/* Take the one with minimum cost. */
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curr[i] = Min(ins, del);
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curr[i] = Min(curr[i], sub);
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}
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/*
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* Lower row now becomes the upper row, and the upper row gets reused
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* as the new lower row.
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*/
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tmp = u_cells;
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u_cells = l_cells;
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l_cells = tmp;
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/*
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* Increment the pointer to str_t
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*/
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str_t++;
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/*
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* Rewind the pointer to str_s
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*/
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str_s = str_s0;
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/* Swap current row with previous row. */
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temp = curr;
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curr = prev;
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prev = temp;
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}
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/*
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* Because the final value (at position row, col) was swapped from the
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* lower row to the upper row, that's where we'll find it.
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* Because the final value was swapped from the previous row to
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* the current row, that's where we'll find it.
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*/
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PG_RETURN_INT32(u_cells[cols - 1]);
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return prev[m-1];
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}
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PG_FUNCTION_INFO_V1(levenshtein_with_costs);
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Datum
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levenshtein_with_costs(PG_FUNCTION_ARGS)
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{
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char *src = TextDatumGetCString(PG_GETARG_DATUM(0));
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char *dst = TextDatumGetCString(PG_GETARG_DATUM(1));
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int ins_c = PG_GETARG_INT32(2);
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int del_c = PG_GETARG_INT32(3);
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int sub_c = PG_GETARG_INT32(4);
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PG_RETURN_INT32(levenshtein_internal(src, dst, ins_c, del_c, sub_c));
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}
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PG_FUNCTION_INFO_V1(levenshtein);
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Datum
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levenshtein(PG_FUNCTION_ARGS)
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{
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char *src = TextDatumGetCString(PG_GETARG_DATUM(0));
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char *dst = TextDatumGetCString(PG_GETARG_DATUM(1));
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PG_RETURN_INT32(levenshtein_internal(src, dst, 1, 1, 1));
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}
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|
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|
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/*
|
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* Calculates the metaphone of an input string.
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* Returns number of characters requested
|
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|
|
@ -249,9 +349,8 @@ metaphone(PG_FUNCTION_ARGS)
|
|||
/*
|
||||
* Original code by Michael G Schwern starts here.
|
||||
* Code slightly modified for use as PostgreSQL
|
||||
* function (palloc, etc). Original includes
|
||||
* are rolled into fuzzystrmatch.h
|
||||
*------------------------------------------------------------------*/
|
||||
* function (palloc, etc).
|
||||
*/
|
||||
|
||||
/* I suppose I could have been using a character pointer instead of
|
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* accessing the array directly... */
|
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|
|
@ -273,7 +372,7 @@ metaphone(PG_FUNCTION_ARGS)
|
|||
|
||||
/* Allows us to safely look ahead an arbitrary # of letters */
|
||||
/* I probably could have just used strlen... */
|
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char
|
||||
static char
|
||||
Lookahead(char *word, int how_far)
|
||||
{
|
||||
char letter_ahead = '\0'; /* null by default */
|
||||
|
|
@ -299,14 +398,10 @@ Lookahead(char *word, int how_far)
|
|||
#define Isbreak(c) (!isalpha((unsigned char) (c)))
|
||||
|
||||
|
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int
|
||||
_metaphone(
|
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/* IN */
|
||||
char *word,
|
||||
static int
|
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_metaphone(char *word, /* IN */
|
||||
int max_phonemes,
|
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/* OUT */
|
||||
char **phoned_word
|
||||
)
|
||||
char **phoned_word) /* OUT */
|
||||
{
|
||||
int w_idx = 0; /* point in the phonization we're at. */
|
||||
int p_idx = 0; /* end of the phoned phrase */
|
||||
|
|
|
|||
|
|
@ -1,171 +0,0 @@
|
|||
/*
|
||||
* fuzzystrmatch.h
|
||||
*
|
||||
* Functions for "fuzzy" comparison of strings
|
||||
*
|
||||
* Joe Conway <mail@joeconway.com>
|
||||
*
|
||||
* $PostgreSQL: pgsql/contrib/fuzzystrmatch/fuzzystrmatch.h,v 1.17 2008/03/25 22:42:41 tgl Exp $
|
||||
* Copyright (c) 2001-2008, PostgreSQL Global Development Group
|
||||
* ALL RIGHTS RESERVED;
|
||||
*
|
||||
* levenshtein()
|
||||
* -------------
|
||||
* Written based on a description of the algorithm by Michael Gilleland
|
||||
* found at http://www.merriampark.com/ld.htm
|
||||
* Also looked at levenshtein.c in the PHP 4.0.6 distribution for
|
||||
* inspiration.
|
||||
*
|
||||
* metaphone()
|
||||
* -----------
|
||||
* Modified for PostgreSQL by Joe Conway.
|
||||
* Based on CPAN's "Text-Metaphone-1.96" by Michael G Schwern <schwern@pobox.com>
|
||||
* Code slightly modified for use as PostgreSQL function (palloc, elog, etc).
|
||||
* Metaphone was originally created by Lawrence Philips and presented in article
|
||||
* in "Computer Language" December 1990 issue.
|
||||
*
|
||||
* Permission to use, copy, modify, and distribute this software and its
|
||||
* documentation for any purpose, without fee, and without a written agreement
|
||||
* is hereby granted, provided that the above copyright notice and this
|
||||
* paragraph and the following two paragraphs appear in all copies.
|
||||
*
|
||||
* IN NO EVENT SHALL THE AUTHORS OR DISTRIBUTORS BE LIABLE TO ANY PARTY FOR
|
||||
* DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES, INCLUDING
|
||||
* LOST PROFITS, ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS
|
||||
* DOCUMENTATION, EVEN IF THE AUTHOR OR DISTRIBUTORS HAVE BEEN ADVISED OF THE
|
||||
* POSSIBILITY OF SUCH DAMAGE.
|
||||
*
|
||||
* THE AUTHORS AND DISTRIBUTORS SPECIFICALLY DISCLAIM ANY WARRANTIES,
|
||||
* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
|
||||
* AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
|
||||
* ON AN "AS IS" BASIS, AND THE AUTHOR AND DISTRIBUTORS HAS NO OBLIGATIONS TO
|
||||
* PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
|
||||
*
|
||||
*/
|
||||
|
||||
#ifndef FUZZYSTRMATCH_H
|
||||
#define FUZZYSTRMATCH_H
|
||||
|
||||
#include "postgres.h"
|
||||
|
||||
#include <ctype.h>
|
||||
|
||||
#include "fmgr.h"
|
||||
#include "utils/builtins.h"
|
||||
|
||||
|
||||
|
||||
/*
|
||||
* External declarations
|
||||
*/
|
||||
extern Datum levenshtein(PG_FUNCTION_ARGS);
|
||||
extern Datum metaphone(PG_FUNCTION_ARGS);
|
||||
extern Datum soundex(PG_FUNCTION_ARGS);
|
||||
extern Datum difference(PG_FUNCTION_ARGS);
|
||||
|
||||
/*
|
||||
* Soundex
|
||||
*/
|
||||
static void _soundex(const char *instr, char *outstr);
|
||||
|
||||
#define SOUNDEX_LEN 4
|
||||
|
||||
/* ABCDEFGHIJKLMNOPQRSTUVWXYZ */
|
||||
static const char *soundex_table = "01230120022455012623010202";
|
||||
|
||||
#define soundex_code(letter) soundex_table[toupper((unsigned char) (letter)) - 'A']
|
||||
|
||||
|
||||
/*
|
||||
* Levenshtein
|
||||
*/
|
||||
#define MAX_LEVENSHTEIN_STRLEN 255
|
||||
|
||||
|
||||
/*
|
||||
* Metaphone
|
||||
*/
|
||||
#define MAX_METAPHONE_STRLEN 255
|
||||
|
||||
/*
|
||||
* Original code by Michael G Schwern starts here.
|
||||
* Code slightly modified for use as PostgreSQL
|
||||
* function (combined *.h into here).
|
||||
*------------------------------------------------------------------*/
|
||||
|
||||
/**************************************************************************
|
||||
metaphone -- Breaks english phrases down into their phonemes.
|
||||
|
||||
Input
|
||||
word -- An english word to be phonized
|
||||
max_phonemes -- How many phonemes to calculate. If 0, then it
|
||||
will phonize the entire phrase.
|
||||
phoned_word -- The final phonized word. (We'll allocate the
|
||||
memory.)
|
||||
Output
|
||||
error -- A simple error flag, returns TRUE or FALSE
|
||||
|
||||
NOTES: ALL non-alpha characters are ignored, this includes whitespace,
|
||||
although non-alpha characters will break up phonemes.
|
||||
****************************************************************************/
|
||||
|
||||
|
||||
/**************************************************************************
|
||||
my constants -- constants I like
|
||||
|
||||
Probably redundant.
|
||||
|
||||
***************************************************************************/
|
||||
|
||||
#define META_ERROR FALSE
|
||||
#define META_SUCCESS TRUE
|
||||
#define META_FAILURE FALSE
|
||||
|
||||
|
||||
/* I add modifications to the traditional metaphone algorithm that you
|
||||
might find in books. Define this if you want metaphone to behave
|
||||
traditionally */
|
||||
#undef USE_TRADITIONAL_METAPHONE
|
||||
|
||||
/* Special encodings */
|
||||
#define SH 'X'
|
||||
#define TH '0'
|
||||
|
||||
char Lookahead(char *word, int how_far);
|
||||
int
|
||||
_metaphone(
|
||||
/* IN */
|
||||
char *word,
|
||||
int max_phonemes,
|
||||
/* OUT */
|
||||
char **phoned_word
|
||||
);
|
||||
|
||||
/* Metachar.h ... little bits about characters for metaphone */
|
||||
|
||||
|
||||
/*-- Character encoding array & accessing macros --*/
|
||||
/* Stolen directly out of the book... */
|
||||
char _codes[26] = {
|
||||
1, 16, 4, 16, 9, 2, 4, 16, 9, 2, 0, 2, 2, 2, 1, 4, 0, 2, 4, 4, 1, 0, 0, 0, 8, 0
|
||||
/* a b c d e f g h i j k l m n o p q r s t u v w x y z */
|
||||
};
|
||||
|
||||
|
||||
#define ENCODE(c) (isalpha((unsigned char) (c)) ? _codes[((toupper((unsigned char) (c))) - 'A')] : 0)
|
||||
|
||||
#define isvowel(c) (ENCODE(c) & 1) /* AEIOU */
|
||||
|
||||
/* These letters are passed through unchanged */
|
||||
#define NOCHANGE(c) (ENCODE(c) & 2) /* FJMNR */
|
||||
|
||||
/* These form dipthongs when preceding H */
|
||||
#define AFFECTH(c) (ENCODE(c) & 4) /* CGPST */
|
||||
|
||||
/* These make C and G soft */
|
||||
#define MAKESOFT(c) (ENCODE(c) & 8) /* EIY */
|
||||
|
||||
/* These prevent GH from becoming F */
|
||||
#define NOGHTOF(c) (ENCODE(c) & 16) /* BDH */
|
||||
|
||||
#endif /* FUZZYSTRMATCH_H */
|
||||
|
|
@ -1,4 +1,4 @@
|
|||
/* $PostgreSQL: pgsql/contrib/fuzzystrmatch/fuzzystrmatch.sql.in,v 1.9 2007/11/13 04:24:28 momjian Exp $ */
|
||||
/* $PostgreSQL: pgsql/contrib/fuzzystrmatch/fuzzystrmatch.sql.in,v 1.10 2008/04/03 21:13:07 tgl Exp $ */
|
||||
|
||||
-- Adjust this setting to control where the objects get created.
|
||||
SET search_path = public;
|
||||
|
|
@ -7,6 +7,10 @@ CREATE OR REPLACE FUNCTION levenshtein (text,text) RETURNS int
|
|||
AS 'MODULE_PATHNAME','levenshtein'
|
||||
LANGUAGE C IMMUTABLE STRICT;
|
||||
|
||||
CREATE OR REPLACE FUNCTION levenshtein (text,text,int,int,int) RETURNS int
|
||||
AS 'MODULE_PATHNAME','levenshtein_with_costs'
|
||||
LANGUAGE C IMMUTABLE STRICT;
|
||||
|
||||
CREATE OR REPLACE FUNCTION metaphone (text,int) RETURNS text
|
||||
AS 'MODULE_PATHNAME','metaphone'
|
||||
LANGUAGE C IMMUTABLE STRICT;
|
||||
|
|
|
|||
|
|
@ -1,4 +1,4 @@
|
|||
/* $PostgreSQL: pgsql/contrib/fuzzystrmatch/uninstall_fuzzystrmatch.sql,v 1.3 2007/11/13 04:24:28 momjian Exp $ */
|
||||
/* $PostgreSQL: pgsql/contrib/fuzzystrmatch/uninstall_fuzzystrmatch.sql,v 1.4 2008/04/03 21:13:07 tgl Exp $ */
|
||||
|
||||
-- Adjust this setting to control where the objects get dropped.
|
||||
SET search_path = public;
|
||||
|
|
@ -15,4 +15,6 @@ DROP FUNCTION soundex(text);
|
|||
|
||||
DROP FUNCTION metaphone (text,int);
|
||||
|
||||
DROP FUNCTION levenshtein (text,text,int,int,int);
|
||||
|
||||
DROP FUNCTION levenshtein (text,text);
|
||||
|
|
|
|||
|
|
@ -1,4 +1,4 @@
|
|||
<!-- $PostgreSQL: pgsql/doc/src/sgml/fuzzystrmatch.sgml,v 1.3 2007/12/06 04:12:10 tgl Exp $ -->
|
||||
<!-- $PostgreSQL: pgsql/doc/src/sgml/fuzzystrmatch.sgml,v 1.4 2008/04/03 21:13:07 tgl Exp $ -->
|
||||
|
||||
<sect1 id="fuzzystrmatch">
|
||||
<title>fuzzystrmatch</title>
|
||||
|
|
@ -74,16 +74,20 @@ SELECT * FROM s WHERE difference(s.nm, 'john') > 2;
|
|||
</para>
|
||||
|
||||
<programlisting>
|
||||
levenshtein(text source, text target, int ins_cost, int del_cost, int sub_cost) returns int
|
||||
levenshtein(text source, text target) returns int
|
||||
</programlisting>
|
||||
|
||||
<para>
|
||||
Both <literal>source</literal> and <literal>target</literal> can be any
|
||||
non-null string, with a maximum of 255 characters.
|
||||
non-null string, with a maximum of 255 bytes. The cost parameters
|
||||
specify how much to charge for a character insertion, deletion, or
|
||||
substitution, respectively. You can omit the cost parameters, as in
|
||||
the second version of the function; in that case they all default to 1.
|
||||
</para>
|
||||
|
||||
<para>
|
||||
Example:
|
||||
Examples:
|
||||
</para>
|
||||
|
||||
<programlisting>
|
||||
|
|
@ -92,6 +96,12 @@ test=# SELECT levenshtein('GUMBO', 'GAMBOL');
|
|||
-------------
|
||||
2
|
||||
(1 row)
|
||||
|
||||
test=# SELECT levenshtein('GUMBO', 'GAMBOL', 2,1,1);
|
||||
levenshtein
|
||||
-------------
|
||||
3
|
||||
(1 row)
|
||||
</programlisting>
|
||||
</sect2>
|
||||
|
||||
|
|
|
|||
Loading…
Reference in New Issue