Re: daitch_mokotoff module
| От | Dag Lem |
|---|---|
| Тема | Re: daitch_mokotoff module |
| Дата | |
| Msg-id | ygetu18tzwt.fsf@sid.nimrod.no обсуждение исходный текст |
| Ответ на | Re: daitch_mokotoff module (Alvaro Herrera <alvherre@alvh.no-ip.org>) |
| Ответы |
Re: daitch_mokotoff module
(Dag Lem <dag@nimrod.no>)
Re: daitch_mokotoff module (Paul Ramsey <pramsey@cleverelephant.ca>) |
| Список | pgsql-hackers |
Sorry about the latest unfinished email - don't know what key
combination I managed to hit there.
Alvaro Herrera <alvherre@alvh.no-ip.org> writes:
> Hello
>
> On 2022-Dec-23, Dag Lem wrote:
>
[...]
>
> So, yes, I'm proposing that we returns those as array elements and that
> @> is used to match them.
>
Looking into the array operators I guess that to match such arrays
directly one would actually use && (overlaps) rather than @> (contains),
but I digress.
The function is changed to return an array of soundex codes - I hope it
is now to your liking :-)
I also improved on the documentation example (using Full Text Search).
AFAIK you can't make general queries like that using arrays, however in
any case I must admit that text arrays seem like more natural building
blocks than space delimited text here.
[...]
>> BTW Vera 790000 does not match Veras 794000, because they don't sound
>> the same (up to the maximum soundex code length).
>
> No, and maybe that's okay because they have different codes. But they
> are both similar, in Daitch-Mokotoff, to Borja, which has two codes,
> 790000 and 794000. (Any Spanish speaker will readily tell you that
> neither Vera nor Veras are similar in any way to Borja, but D-M has
> chosen to say that each of them matches one of Borjas' codes. So they
> *are* related, even though indirectly, and as a genealogist you *may* be
> interested in getting a match for a person called Vera when looking for
> relatives to a person called Veras. And, as a Spanish speaker, that
> would make a lot of sense to me.)
It is what it is - we can't call it Daitch-Mokotoff Soundex while
implementing something else. Having said that, one can always pre- or
postprocess to tweak the results.
Daitch-Mokotoff Soundex is known to produce false positives, but that is
in many cases not a problem.
Even though it's clearly tuned for Jewish names, the soundex algorithm
seems to work just fine for European names (we use it to match mostly
Norwegian names).
Best regards
Dag Lem
diff --git a/contrib/fuzzystrmatch/Makefile b/contrib/fuzzystrmatch/Makefile
index 0704894f88..12baf2d884 100644
--- a/contrib/fuzzystrmatch/Makefile
+++ b/contrib/fuzzystrmatch/Makefile
@@ -3,14 +3,15 @@
MODULE_big = fuzzystrmatch
OBJS = \
$(WIN32RES) \
+ daitch_mokotoff.o \
dmetaphone.o \
fuzzystrmatch.o
EXTENSION = fuzzystrmatch
-DATA = fuzzystrmatch--1.1.sql fuzzystrmatch--1.0--1.1.sql
+DATA = fuzzystrmatch--1.1.sql fuzzystrmatch--1.1--1.2.sql fuzzystrmatch--1.0--1.1.sql
PGFILEDESC = "fuzzystrmatch - similarities and distance between strings"
-REGRESS = fuzzystrmatch
+REGRESS = fuzzystrmatch fuzzystrmatch_utf8
ifdef USE_PGXS
PG_CONFIG = pg_config
@@ -22,3 +23,14 @@ top_builddir = ../..
include $(top_builddir)/src/Makefile.global
include $(top_srcdir)/contrib/contrib-global.mk
endif
+
+# Force this dependency to be known even without dependency info built:
+daitch_mokotoff.o: daitch_mokotoff.h
+
+daitch_mokotoff.h: daitch_mokotoff_header.pl
+ perl $< $@
+
+distprep: daitch_mokotoff.h
+
+maintainer-clean:
+ rm -f daitch_mokotoff.h
diff --git a/contrib/fuzzystrmatch/daitch_mokotoff.c b/contrib/fuzzystrmatch/daitch_mokotoff.c
new file mode 100644
index 0000000000..2548903770
--- /dev/null
+++ b/contrib/fuzzystrmatch/daitch_mokotoff.c
@@ -0,0 +1,582 @@
+/*
+ * Daitch-Mokotoff Soundex
+ *
+ * Copyright (c) 2021 Finance Norway
+ * Author: Dag Lem <dag@nimrod.no>
+ *
+ * This implementation of the Daitch-Mokotoff Soundex System aims at high
+ * performance.
+ *
+ * - The processing of each phoneme is initiated by an O(1) table lookup.
+ * - For phonemes containing more than one character, a coding tree is traversed
+ * to process the complete phoneme.
+ * - The (alternate) soundex codes are produced digit by digit in-place in
+ * another tree structure.
+ *
+ * References:
+ *
+ * https://www.avotaynu.com/soundex.htm
+ * https://www.jewishgen.org/InfoFiles/Soundex.html
+ * https://familypedia.fandom.com/wiki/Daitch-Mokotoff_Soundex
+ * https://stevemorse.org/census/soundex.html (dmlat.php, dmsoundex.php)
+ * https://github.com/apache/commons-codec/ (dmrules.txt, DaitchMokotoffSoundex.java)
+ * https://metacpan.org/pod/Text::Phonetic (DaitchMokotoff.pm)
+ *
+ * A few notes on other implementations:
+ *
+ * - All other known implementations have the same unofficial rules for "UE",
+ * these are also adapted by this implementation (0, 1, NC).
+ * - The only other known implementation which is capable of generating all
+ * correct soundex codes in all cases is the JOS Soundex Calculator at
+ * https://www.jewishgen.org/jos/jossound.htm
+ * - "J" is considered (only) a vowel in dmlat.php
+ * - The official rules for "RS" are commented out in dmlat.php
+ * - Identical code digits for adjacent letters are not collapsed correctly in
+ * dmsoundex.php when double digit codes are involved. E.g. "BESST" yields
+ * 744300 instead of 743000 as for "BEST".
+ * - "J" is considered (only) a consonant in DaitchMokotoffSoundex.java
+ * - "Y" is not considered a vowel in DaitchMokotoffSoundex.java
+ *
+ * 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 AUTHOR 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 AUTHOR 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.
+*/
+
+#include "postgres.h"
+
+#include "catalog/pg_type.h"
+#include "mb/pg_wchar.h"
+#include "utils/array.h"
+#include "utils/builtins.h"
+#include "utils/memutils.h"
+
+
+/*
+ * The soundex coding chart table is adapted from
+ * https://www.jewishgen.org/InfoFiles/Soundex.html
+ * See daitch_mokotoff_header.pl for details.
+*/
+
+/* Generated coding chart table */
+#include "daitch_mokotoff.h"
+
+#define DM_CODE_DIGITS 6
+
+/* Node in soundex code tree */
+struct dm_node
+{
+ int soundex_length; /* Length of generated soundex code */
+ char soundex[DM_CODE_DIGITS]; /* Soundex code */
+ int is_leaf; /* Candidate for complete soundex code */
+ int last_update; /* Letter number for last update of node */
+ char code_digit; /* Last code digit, 0 - 9 */
+
+ /*
+ * One or two alternate code digits leading to this node. If there are two
+ * digits, one of them is always an 'X'. Repeated code digits and 'X' lead
+ * back to the same node.
+ */
+ char prev_code_digits[2];
+ /* One or two alternate code digits moving forward. */
+ char next_code_digits[2];
+ /* ORed together code index(es) used to reach current node. */
+ int prev_code_index;
+ int next_code_index;
+ /* Possible nodes branching out from this node - digits 0-9. */
+ struct dm_node *children[10];
+ /* Next node in linked list. Alternating index for each iteration. */
+ struct dm_node *next[2];
+};
+
+typedef struct dm_node dm_node;
+
+
+/* Internal C implementation */
+static int daitch_mokotoff_coding(char *word, ArrayBuildState *soundex, MemoryContext tmp_ctx);
+
+
+PG_FUNCTION_INFO_V1(daitch_mokotoff);
+
+Datum
+daitch_mokotoff(PG_FUNCTION_ARGS)
+{
+ text *arg = PG_GETARG_TEXT_PP(0);
+ char *string;
+ ArrayBuildState *soundex;
+ Datum retval;
+ MemoryContext mem_ctx,
+ tmp_ctx;
+
+ tmp_ctx = AllocSetContextCreate(CurrentMemoryContext,
+ "daitch_mokotoff temporary context",
+ ALLOCSET_DEFAULT_SIZES);
+ mem_ctx = MemoryContextSwitchTo(tmp_ctx);
+
+ string = pg_server_to_any(text_to_cstring(arg), VARSIZE_ANY_EXHDR(arg), PG_UTF8);
+ soundex = initArrayResult(TEXTOID, tmp_ctx, false);
+
+ if (!daitch_mokotoff_coding(string, soundex, tmp_ctx))
+ {
+ /* No encodable characters in input. */
+ MemoryContextSwitchTo(mem_ctx);
+ MemoryContextDelete(tmp_ctx);
+ PG_RETURN_NULL();
+ }
+
+ retval = makeArrayResult(soundex, mem_ctx);
+ MemoryContextSwitchTo(mem_ctx);
+ MemoryContextDelete(tmp_ctx);
+
+ PG_RETURN_DATUM(retval);
+}
+
+
+/* Template for new node in soundex code tree. */
+static const dm_node start_node = {
+ .soundex_length = 0,
+ .soundex = "000000", /* Six digits */
+ .is_leaf = 0,
+ .last_update = 0,
+ .code_digit = '\0',
+ .prev_code_digits = {'\0', '\0'},
+ .next_code_digits = {'\0', '\0'},
+ .prev_code_index = 0,
+ .next_code_index = 0,
+ .children = {NULL},
+ .next = {NULL}
+};
+
+/* Dummy soundex codes at end of input. */
+static const dm_codes end_codes[2] =
+{
+ {
+ "X", "X", "X"
+ }
+};
+
+
+/* Initialize soundex code tree node for next code digit. */
+static void
+initialize_node(dm_node * node, int last_update)
+{
+ if (node->last_update < last_update)
+ {
+ node->prev_code_digits[0] = node->next_code_digits[0];
+ node->prev_code_digits[1] = node->next_code_digits[1];
+ node->next_code_digits[0] = '\0';
+ node->next_code_digits[1] = '\0';
+ node->prev_code_index = node->next_code_index;
+ node->next_code_index = 0;
+ node->is_leaf = 0;
+ node->last_update = last_update;
+ }
+}
+
+
+/* Update soundex code tree node with next code digit. */
+static void
+add_next_code_digit(dm_node * node, int code_index, char code_digit)
+{
+ /* OR in index 1 or 2. */
+ node->next_code_index |= code_index;
+
+ if (!node->next_code_digits[0])
+ {
+ node->next_code_digits[0] = code_digit;
+ }
+ else if (node->next_code_digits[0] != code_digit)
+ {
+ node->next_code_digits[1] = code_digit;
+ }
+}
+
+
+/* Mark soundex code tree node as leaf. */
+static void
+set_leaf(dm_node * first_node[2], dm_node * last_node[2], dm_node * node, int ix_node)
+{
+ if (!node->is_leaf)
+ {
+ node->is_leaf = 1;
+
+ if (first_node[ix_node] == NULL)
+ {
+ first_node[ix_node] = node;
+ }
+ else
+ {
+ last_node[ix_node]->next[ix_node] = node;
+ }
+
+ last_node[ix_node] = node;
+ node->next[ix_node] = NULL;
+ }
+}
+
+
+/* Find next node corresponding to code digit, or create a new node. */
+static dm_node *
+find_or_create_child_node(dm_node * parent, char code_digit, ArrayBuildState *soundex, MemoryContext tmp_ctx)
+{
+ int i = code_digit - '0';
+ dm_node **nodes = parent->children;
+ dm_node *node = nodes[i];
+
+ if (node)
+ {
+ /* Found existing child node. Skip completed nodes. */
+ return node->soundex_length < DM_CODE_DIGITS ? node : NULL;
+ }
+
+ /* Create new child node. */
+ node = palloc(sizeof(dm_node));
+ nodes[i] = node;
+
+ *node = start_node;
+ memcpy(node->soundex, parent->soundex, sizeof(parent->soundex));
+ node->soundex_length = parent->soundex_length;
+ node->soundex[node->soundex_length++] = code_digit;
+ node->code_digit = code_digit;
+ node->next_code_index = node->prev_code_index;
+
+ if (node->soundex_length < DM_CODE_DIGITS)
+ {
+ return node;
+ }
+ else
+ {
+ /* Append completed soundex code to soundex array. */
+ accumArrayResult(soundex,
+ PointerGetDatum(cstring_to_text_with_len(node->soundex, DM_CODE_DIGITS)),
+ false,
+ TEXTOID,
+ tmp_ctx);
+ return NULL;
+ }
+}
+
+
+/* Update node for next code digit(s). */
+static void
+update_node(dm_node * first_node[2], dm_node * last_node[2], dm_node * node, int ix_node,
+ int letter_no, int prev_code_index, int next_code_index,
+ const char *next_code_digits, int digit_no,
+ ArrayBuildState *soundex, MemoryContext tmp_ctx)
+{
+ int i;
+ char next_code_digit = next_code_digits[digit_no];
+ int num_dirty_nodes = 0;
+ dm_node *dirty_nodes[2];
+
+ initialize_node(node, letter_no);
+
+ if (node->prev_code_index && !(node->prev_code_index & prev_code_index))
+ {
+ /*
+ * If the sound (vowel / consonant) of this letter encoding doesn't
+ * correspond to the coding index of the previous letter, we skip this
+ * letter encoding. Note that currently, only "J" can be either a
+ * vowel or a consonant.
+ */
+ return;
+ }
+
+ if (next_code_digit == 'X' ||
+ (digit_no == 0 &&
+ (node->prev_code_digits[0] == next_code_digit ||
+ node->prev_code_digits[1] == next_code_digit)))
+ {
+ /* The code digit is the same as one of the previous (i.e. not added). */
+ dirty_nodes[num_dirty_nodes++] = node;
+ }
+
+ if (next_code_digit != 'X' &&
+ (digit_no > 0 ||
+ node->prev_code_digits[0] != next_code_digit ||
+ node->prev_code_digits[1]))
+ {
+ /* The code digit is different from one of the previous (i.e. added). */
+ node = find_or_create_child_node(node, next_code_digit, soundex, tmp_ctx);
+ if (node)
+ {
+ initialize_node(node, letter_no);
+ dirty_nodes[num_dirty_nodes++] = node;
+ }
+ }
+
+ for (i = 0; i < num_dirty_nodes; i++)
+ {
+ /* Add code digit leading to the current node. */
+ add_next_code_digit(dirty_nodes[i], next_code_index, next_code_digit);
+
+ if (next_code_digits[++digit_no])
+ {
+ update_node(first_node, last_node, dirty_nodes[i], ix_node,
+ letter_no, prev_code_index, next_code_index,
+ next_code_digits, digit_no,
+ soundex, tmp_ctx);
+ }
+ else
+ {
+ /* Add incomplete leaf node to linked list. */
+ set_leaf(first_node, last_node, dirty_nodes[i], ix_node);
+ }
+ }
+}
+
+
+/* Update soundex tree leaf nodes. */
+static void
+update_leaves(dm_node * first_node[2], int *ix_node, int letter_no,
+ const dm_codes * codes, const dm_codes * next_codes,
+ ArrayBuildState *soundex, MemoryContext tmp_ctx)
+{
+ int i,
+ j,
+ code_index;
+ dm_node *node,
+ *last_node[2];
+ const dm_code *code,
+ *next_code;
+ int ix_node_next = (*ix_node + 1) & 1; /* Alternating index: 0, 1 */
+
+ /* Initialize for new linked list of leaves. */
+ first_node[ix_node_next] = NULL;
+ last_node[ix_node_next] = NULL;
+
+ /* Process all nodes. */
+ for (node = first_node[*ix_node]; node; node = node->next[*ix_node])
+ {
+ /* One or two alternate code sequences. */
+ for (i = 0; i < 2 && (code = codes[i]) && code[0][0]; i++)
+ {
+ /* Coding for previous letter - before vowel: 1, all other: 2 */
+ int prev_code_index = (code[0][0] > '1') + 1;
+
+ /* One or two alternate next code sequences. */
+ for (j = 0; j < 2 && (next_code = next_codes[j]) && next_code[0][0]; j++)
+ {
+ /* Determine which code to use. */
+ if (letter_no == 0)
+ {
+ /* This is the first letter. */
+ code_index = 0;
+ }
+ else if (next_code[0][0] <= '1')
+ {
+ /* The next letter is a vowel. */
+ code_index = 1;
+ }
+ else
+ {
+ /* All other cases. */
+ code_index = 2;
+ }
+
+ /* One or two sequential code digits. */
+ update_node(first_node, last_node, node, ix_node_next,
+ letter_no, prev_code_index, code_index,
+ code[code_index], 0,
+ soundex, tmp_ctx);
+ }
+ }
+ }
+
+ *ix_node = ix_node_next;
+}
+
+
+/* Mapping from ISO8859-1 to upper-case ASCII */
+static const char iso8859_1_to_ascii_upper[] =
+/*
+"`abcdefghijklmnopqrstuvwxyz{|}~ ¡¢£¤¥¦§¨©ª«¬
®¯°±²³´µ¶·¸¹º»¼½¾¿ÀÁÂÃÄÅÆÇÈÉÊËÌÍÎÏÐÑÒÓÔÕÖ×ØÙÚÛÜÝÞßàáâãäåæçèéêëìíîïðñòóôõö÷øùúûüýþÿ"
+*/
+"`ABCDEFGHIJKLMNOPQRSTUVWXYZ{|}~ !
?AAAAAAECEEEEIIIIDNOOOOO*OUUUUYDSAAAAAAECEEEEIIIIDNOOOOO/OUUUUYDY";
+
+
+/* Return next character, converted from UTF-8 to uppercase ASCII. */
+static char
+read_char(unsigned char *str, int *ix)
+{
+ /* Substitute character for skipped code points. */
+ const char na = '\x1a';
+ pg_wchar c;
+
+ /* Decode UTF-8 character to ISO 10646 code point. */
+ str += *ix;
+ c = utf8_to_unicode(str);
+ *ix += pg_utf_mblen(str);
+
+ if (c >= (unsigned char) '[' && c <= (unsigned char) ']')
+ {
+ /* ASCII characters [, \, and ] are reserved for Ą, Ę, and Ţ/Ț. */
+ return na;
+ }
+ else if (c < 0x60)
+ {
+ /* Non-lowercase ASCII character. */
+ return c;
+ }
+ else if (c < 0x100)
+ {
+ /* ISO-8859-1 code point, converted to upper-case ASCII. */
+ return iso8859_1_to_ascii_upper[c - 0x60];
+ }
+ else
+ {
+ /* Conversion of non-ASCII characters in the coding chart. */
+ switch (c)
+ {
+ case 0x0104:
+ case 0x0105:
+ /* Ą/ą */
+ return '[';
+ case 0x0118:
+ case 0x0119:
+ /* Ę/ę */
+ return '\\';
+ case 0x0162:
+ case 0x0163:
+ case 0x021A:
+ case 0x021B:
+ /* Ţ/ţ or Ț/ț */
+ return ']';
+ default:
+ return na;
+ }
+ }
+}
+
+
+/* Read next ASCII character, skipping any characters not in [A-\]]. */
+static char
+read_valid_char(char *str, int *ix)
+{
+ char c;
+
+ while ((c = read_char((unsigned char *) str, ix)))
+ {
+ if (c >= 'A' && c <= ']')
+ {
+ break;
+ }
+ }
+
+ return c;
+}
+
+
+/* Return sound coding for "letter" (letter sequence) */
+static const dm_codes *
+read_letter(char *str, int *ix)
+{
+ char c,
+ cmp;
+ int i,
+ j;
+ const dm_letter *letters;
+ const dm_codes *codes;
+
+ /* First letter in sequence. */
+ if (!(c = read_valid_char(str, ix)))
+ {
+ return NULL;
+ }
+ letters = &letter_[c - 'A'];
+ codes = letters->codes;
+ i = *ix;
+
+ /* Any subsequent letters in sequence. */
+ while ((letters = letters->letters) && (c = read_valid_char(str, &i)))
+ {
+ for (j = 0; (cmp = letters[j].letter); j++)
+ {
+ if (cmp == c)
+ {
+ /* Letter found. */
+ letters = &letters[j];
+ if (letters->codes)
+ {
+ /* Coding for letter sequence found. */
+ codes = letters->codes;
+ *ix = i;
+ }
+ break;
+ }
+ }
+ if (!cmp)
+ {
+ /* The sequence of letters has no coding. */
+ break;
+ }
+ }
+
+ return codes;
+}
+
+
+/* Generate all Daitch-Mokotoff soundex codes for word. */
+static int
+daitch_mokotoff_coding(char *word, ArrayBuildState *soundex, MemoryContext tmp_ctx)
+{
+ int i = 0;
+ int letter_no = 0;
+ int ix_node = 0;
+ const dm_codes *codes,
+ *next_codes;
+ dm_node *first_node[2],
+ *node;
+
+ /* First letter. */
+ if (!(codes = read_letter(word, &i)))
+ {
+ /* No encodable character in input. */
+ return 0;
+ }
+
+ /* Starting point. */
+ first_node[ix_node] = palloc(sizeof(dm_node));
+ *first_node[ix_node] = start_node;
+
+ /*
+ * Loop until either the word input is exhausted, or all generated soundex
+ * codes are completed to six digits.
+ */
+ while (codes && first_node[ix_node])
+ {
+ next_codes = read_letter(word, &i);
+
+ /* Update leaf nodes. */
+ update_leaves(first_node, &ix_node, letter_no,
+ codes, next_codes ? next_codes : end_codes,
+ soundex, tmp_ctx);
+
+ codes = next_codes;
+ letter_no++;
+ }
+
+ /* Append all remaining (incomplete) soundex codes. */
+ for (node = first_node[ix_node]; node; node = node->next[ix_node])
+ {
+ accumArrayResult(soundex,
+ PointerGetDatum(cstring_to_text_with_len(node->soundex, DM_CODE_DIGITS)),
+ false,
+ TEXTOID,
+ tmp_ctx);
+ }
+
+ return 1;
+}
diff --git a/contrib/fuzzystrmatch/daitch_mokotoff_header.pl b/contrib/fuzzystrmatch/daitch_mokotoff_header.pl
new file mode 100755
index 0000000000..c888847ad0
--- /dev/null
+++ b/contrib/fuzzystrmatch/daitch_mokotoff_header.pl
@@ -0,0 +1,240 @@
+#!/bin/perl
+#
+# Generation of types and lookup tables for Daitch-Mokotoff soundex.
+#
+# Copyright (c) 2021 Finance Norway
+# Author: Dag Lem <dag@nimrod.no>
+#
+# 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 AUTHOR 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 AUTHOR 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.
+#
+
+use strict;
+use warnings;
+use utf8;
+use open IO => ':utf8', ':std';
+use Data::Dumper;
+
+die "Usage: $0 OUTPUT_FILE\n" if @ARGV != 1;
+my $output_file = $ARGV[0];
+
+# Open the output file
+open my $OUTPUT, '>', $output_file
+ or die "Could not open output file $output_file: $!\n";
+
+# Parse code table and generate tree for letter transitions.
+my %codes;
+my $table = [{}, [["","",""]]];
+while (<DATA>) {
+ chomp;
+ my ($letters, $codes) = split(/\s+/);
+ my @codes = map { [ split(/,/) ] } split(/\|/, $codes);
+
+ my $key = "codes_" . join("_or_", map { join("_", @$_) } @codes);
+ my $val = join(",\n", map { "\t{\n\t\t" . join(", ", map { "\"$_\"" } @$_) . "\n\t}" } @codes);
+ $codes{$key} = $val;
+
+ for my $letter (split(/,/, $letters)) {
+ my $ref = $table->[0];
+ # Link each character to the next in the letter combination.
+ my @c = split(//, $letter);
+ my $last_c = pop(@c);
+ for my $c (@c) {
+ $ref->{$c} //= [ {}, undef ];
+ $ref->{$c}[0] //= {};
+ $ref = $ref->{$c}[0];
+ }
+ # The sound code for the letter combination is stored at the last character.
+ $ref->{$last_c}[1] = $key;
+ }
+}
+close(DATA);
+
+print $OUTPUT <<EOF;
+/*
+ * Constants and lookup tables for Daitch-Mokotoff Soundex
+ *
+ * Copyright (c) 2021 Finance Norway
+ * Author: Dag Lem <dag\@nimrod.no>
+ *
+ * This file is generated by daitch_mokotoff_header.pl
+ *
+ * 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 AUTHOR 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 AUTHOR 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.
+ */
+
+/* Coding chart table: Soundex codes */
+typedef char dm_code[2 + 1]; /* One or two sequential code digits + NUL */
+typedef dm_code dm_codes[3]; /* Start of name, before a vowel, any other */
+
+/* Coding chart table: Letter in input sequence */
+struct dm_letter
+{
+ char letter; /* Present letter in sequence */
+ const struct dm_letter *letters; /* List of possible successive letters */
+ const dm_codes *codes; /* Code sequence(s) for complete sequence */
+};
+
+typedef struct dm_letter dm_letter;
+
+/* Codes for letter sequence at start of name, before a vowel, and any other. */
+EOF
+
+for my $key (sort keys %codes) {
+ print $OUTPUT "static const dm_codes $key\[2\] =\n{\n" . $codes{$key} . "\n};\n";
+}
+
+print $OUTPUT <<EOF;
+
+/* Coding for alternative following letters in sequence. */
+EOF
+
+sub hash2code {
+ my ($ref, $letter) = @_;
+
+ my @letters = ();
+
+ my $h = $ref->[0];
+ for my $key (sort keys %$h) {
+ $ref = $h->{$key};
+ my $children = "NULL";
+ if (defined $ref->[0]) {
+ $children = "letter_$letter$key";
+ hash2code($ref, "$letter$key");
+ }
+ my $codes = $ref->[1] // "NULL";
+ push(@letters, "\t{\n\t\t'$key', $children, $codes\n\t}");
+ }
+
+ print $OUTPUT "static const dm_letter letter_$letter\[\] =\n{\n";
+ for (@letters) {
+ print $OUTPUT "$_,\n";
+ }
+ print $OUTPUT "\t{\n\t\t'\\0'\n\t}\n";
+ print $OUTPUT "};\n";
+}
+
+hash2code($table, '');
+
+close $OUTPUT;
+
+# Table adapted from https://www.jewishgen.org/InfoFiles/Soundex.html
+#
+# The conversion from the coding chart to the table should be self
+# explanatory, but note the differences stated below.
+#
+# X = NC (not coded)
+#
+# The non-ASCII letters in the coding chart are coded with substitute
+# lowercase ASCII letters, which sort after the uppercase ASCII letters:
+#
+# Ą => a (use '[' for table lookup)
+# Ę => e (use '\\' for table lookup)
+# Ţ => t (use ']' for table lookup)
+#
+# The rule for "UE" does not correspond to the coding chart, however
+# it is used by all other known implementations, including the one at
+# https://www.jewishgen.org/jos/jossound.htm (try e.g. "bouey").
+#
+# Note that the implementation assumes that vowels are assigned code
+# 0 or 1. "J" can be either a vowel or a consonant.
+#
+
+__DATA__
+AI,AJ,AY 0,1,X
+AU 0,7,X
+a X,X,6|X,X,X
+A 0,X,X
+B 7,7,7
+CHS 5,54,54
+CH 5,5,5|4,4,4
+CK 5,5,5|45,45,45
+CZ,CS,CSZ,CZS 4,4,4
+C 5,5,5|4,4,4
+DRZ,DRS 4,4,4
+DS,DSH,DSZ 4,4,4
+DZ,DZH,DZS 4,4,4
+D,DT 3,3,3
+EI,EJ,EY 0,1,X
+EU 1,1,X
+e X,X,6|X,X,X
+E 0,X,X
+FB 7,7,7
+F 7,7,7
+G 5,5,5
+H 5,5,X
+IA,IE,IO,IU 1,X,X
+I 0,X,X
+J 1,X,X|4,4,4
+KS 5,54,54
+KH 5,5,5
+K 5,5,5
+L 8,8,8
+MN 66,66,66
+M 6,6,6
+NM 66,66,66
+N 6,6,6
+OI,OJ,OY 0,1,X
+O 0,X,X
+P,PF,PH 7,7,7
+Q 5,5,5
+RZ,RS 94,94,94|4,4,4
+R 9,9,9
+SCHTSCH,SCHTSH,SCHTCH 2,4,4
+SCH 4,4,4
+SHTCH,SHCH,SHTSH 2,4,4
+SHT,SCHT,SCHD 2,43,43
+SH 4,4,4
+STCH,STSCH,SC 2,4,4
+STRZ,STRS,STSH 2,4,4
+ST 2,43,43
+SZCZ,SZCS 2,4,4
+SZT,SHD,SZD,SD 2,43,43
+SZ 4,4,4
+S 4,4,4
+TCH,TTCH,TTSCH 4,4,4
+TH 3,3,3
+TRZ,TRS 4,4,4
+TSCH,TSH 4,4,4
+TS,TTS,TTSZ,TC 4,4,4
+TZ,TTZ,TZS,TSZ 4,4,4
+t 3,3,3|4,4,4
+T 3,3,3
+UI,UJ,UY,UE 0,1,X
+U 0,X,X
+V 7,7,7
+W 7,7,7
+X 5,54,54
+Y 1,X,X
+ZDZ,ZDZH,ZHDZH 2,4,4
+ZD,ZHD 2,43,43
+ZH,ZS,ZSCH,ZSH 4,4,4
+Z 4,4,4
diff --git a/contrib/fuzzystrmatch/expected/fuzzystrmatch.out b/contrib/fuzzystrmatch/expected/fuzzystrmatch.out
index 493c95cdfa..bcb837fd6b 100644
--- a/contrib/fuzzystrmatch/expected/fuzzystrmatch.out
+++ b/contrib/fuzzystrmatch/expected/fuzzystrmatch.out
@@ -65,3 +65,174 @@ SELECT dmetaphone_alt('gumbo');
KMP
(1 row)
+-- Wovels
+SELECT daitch_mokotoff('Augsburg');
+ daitch_mokotoff
+-----------------
+ {054795}
+(1 row)
+
+SELECT daitch_mokotoff('Breuer');
+ daitch_mokotoff
+-----------------
+ {791900}
+(1 row)
+
+SELECT daitch_mokotoff('Freud');
+ daitch_mokotoff
+-----------------
+ {793000}
+(1 row)
+
+-- The letter "H"
+SELECT daitch_mokotoff('Halberstadt');
+ daitch_mokotoff
+-----------------
+ {587943,587433}
+(1 row)
+
+SELECT daitch_mokotoff('Mannheim');
+ daitch_mokotoff
+-----------------
+ {665600}
+(1 row)
+
+-- Adjacent sounds
+SELECT daitch_mokotoff('Chernowitz');
+ daitch_mokotoff
+-----------------
+ {596740,496740}
+(1 row)
+
+-- Adjacent letters with identical adjacent code digits
+SELECT daitch_mokotoff('Cherkassy');
+ daitch_mokotoff
+-----------------
+ {595400,495400}
+(1 row)
+
+SELECT daitch_mokotoff('Kleinman');
+ daitch_mokotoff
+-----------------
+ {586660}
+(1 row)
+
+-- More than one word
+SELECT daitch_mokotoff('Nowy Targ');
+ daitch_mokotoff
+-----------------
+ {673950}
+(1 row)
+
+-- Padded with "0"
+SELECT daitch_mokotoff('Berlin');
+ daitch_mokotoff
+-----------------
+ {798600}
+(1 row)
+
+-- Other examples from https://www.avotaynu.com/soundex.htm
+SELECT daitch_mokotoff('Ceniow');
+ daitch_mokotoff
+-----------------
+ {567000,467000}
+(1 row)
+
+SELECT daitch_mokotoff('Tsenyuv');
+ daitch_mokotoff
+-----------------
+ {467000}
+(1 row)
+
+SELECT daitch_mokotoff('Holubica');
+ daitch_mokotoff
+-----------------
+ {587500,587400}
+(1 row)
+
+SELECT daitch_mokotoff('Golubitsa');
+ daitch_mokotoff
+-----------------
+ {587400}
+(1 row)
+
+SELECT daitch_mokotoff('Przemysl');
+ daitch_mokotoff
+-----------------
+ {794648,746480}
+(1 row)
+
+SELECT daitch_mokotoff('Pshemeshil');
+ daitch_mokotoff
+-----------------
+ {746480}
+(1 row)
+
+SELECT daitch_mokotoff('Rosochowaciec');
+ daitch_mokotoff
+-----------------------------------------------------------
+ {945755,945754,945745,945744,944755,944754,944745,944744}
+(1 row)
+
+SELECT daitch_mokotoff('Rosokhovatsets');
+ daitch_mokotoff
+-----------------
+ {945744}
+(1 row)
+
+-- Ignored characters
+SELECT daitch_mokotoff('''OBrien');
+ daitch_mokotoff
+-----------------
+ {079600}
+(1 row)
+
+SELECT daitch_mokotoff('O''Brien');
+ daitch_mokotoff
+-----------------
+ {079600}
+(1 row)
+
+-- "Difficult" cases, likely to cause trouble for other implementations.
+SELECT daitch_mokotoff('CJC');
+ daitch_mokotoff
+---------------------------------------------
+ {550000,540000,545000,450000,400000,440000}
+(1 row)
+
+SELECT daitch_mokotoff('BESST');
+ daitch_mokotoff
+-----------------
+ {743000}
+(1 row)
+
+SELECT daitch_mokotoff('BOUEY');
+ daitch_mokotoff
+-----------------
+ {710000}
+(1 row)
+
+SELECT daitch_mokotoff('HANNMANN');
+ daitch_mokotoff
+-----------------
+ {566600}
+(1 row)
+
+SELECT daitch_mokotoff('MCCOYJR');
+ daitch_mokotoff
+-----------------------------------------------------------
+ {651900,654900,654190,654490,645190,645490,641900,644900}
+(1 row)
+
+SELECT daitch_mokotoff('ACCURSO');
+ daitch_mokotoff
+-----------------------------------------------------------
+ {059400,054000,054940,054400,045940,045400,049400,044000}
+(1 row)
+
+SELECT daitch_mokotoff('BIERSCHBACH');
+ daitch_mokotoff
+-----------------------------------------------------------
+ {794575,794574,794750,794740,745750,745740,747500,747400}
+(1 row)
+
diff --git a/contrib/fuzzystrmatch/expected/fuzzystrmatch_utf8.out
b/contrib/fuzzystrmatch/expected/fuzzystrmatch_utf8.out
new file mode 100644
index 0000000000..b0dd4880ba
--- /dev/null
+++ b/contrib/fuzzystrmatch/expected/fuzzystrmatch_utf8.out
@@ -0,0 +1,61 @@
+/*
+ * This test must be run in a database with UTF-8 encoding,
+ * because other encodings don't support all the characters used.
+ */
+SELECT getdatabaseencoding() <> 'UTF8'
+ AS skip_test \gset
+\if :skip_test
+\quit
+\endif
+set client_encoding = utf8;
+-- CREATE EXTENSION IF NOT EXISTS fuzzystrmatch;
+-- Accents
+SELECT daitch_mokotoff('Müller');
+ daitch_mokotoff
+-----------------
+ {689000}
+(1 row)
+
+SELECT daitch_mokotoff('Schäfer');
+ daitch_mokotoff
+-----------------
+ {479000}
+(1 row)
+
+SELECT daitch_mokotoff('Straßburg');
+ daitch_mokotoff
+-----------------
+ {294795}
+(1 row)
+
+SELECT daitch_mokotoff('Éregon');
+ daitch_mokotoff
+-----------------
+ {095600}
+(1 row)
+
+-- Special characters added at https://www.jewishgen.org/InfoFiles/Soundex.html
+SELECT daitch_mokotoff('gąszczu');
+ daitch_mokotoff
+-----------------
+ {564000,540000}
+(1 row)
+
+SELECT daitch_mokotoff('brzęczy');
+ daitch_mokotoff
+-------------------------------
+ {794640,794400,746400,744000}
+(1 row)
+
+SELECT daitch_mokotoff('ţamas');
+ daitch_mokotoff
+-----------------
+ {364000,464000}
+(1 row)
+
+SELECT daitch_mokotoff('țamas');
+ daitch_mokotoff
+-----------------
+ {364000,464000}
+(1 row)
+
diff --git a/contrib/fuzzystrmatch/expected/fuzzystrmatch_utf8_1.out
b/contrib/fuzzystrmatch/expected/fuzzystrmatch_utf8_1.out
new file mode 100644
index 0000000000..37aead89c0
--- /dev/null
+++ b/contrib/fuzzystrmatch/expected/fuzzystrmatch_utf8_1.out
@@ -0,0 +1,8 @@
+/*
+ * This test must be run in a database with UTF-8 encoding,
+ * because other encodings don't support all the characters used.
+ */
+SELECT getdatabaseencoding() <> 'UTF8'
+ AS skip_test \gset
+\if :skip_test
+\quit
diff --git a/contrib/fuzzystrmatch/fuzzystrmatch--1.1--1.2.sql b/contrib/fuzzystrmatch/fuzzystrmatch--1.1--1.2.sql
new file mode 100644
index 0000000000..d8542a781c
--- /dev/null
+++ b/contrib/fuzzystrmatch/fuzzystrmatch--1.1--1.2.sql
@@ -0,0 +1,8 @@
+/* contrib/fuzzystrmatch/fuzzystrmatch--1.1--1.2.sql */
+
+-- complain if script is sourced in psql, rather than via ALTER EXTENSION
+\echo Use "ALTER EXTENSION fuzzystrmatch UPDATE TO '1.2'" to load this file. \quit
+
+CREATE FUNCTION daitch_mokotoff(text) RETURNS text[]
+AS 'MODULE_PATHNAME', 'daitch_mokotoff'
+LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;
diff --git a/contrib/fuzzystrmatch/fuzzystrmatch.control b/contrib/fuzzystrmatch/fuzzystrmatch.control
index 3cd6660bf9..8b6e9fd993 100644
--- a/contrib/fuzzystrmatch/fuzzystrmatch.control
+++ b/contrib/fuzzystrmatch/fuzzystrmatch.control
@@ -1,6 +1,6 @@
# fuzzystrmatch extension
comment = 'determine similarities and distance between strings'
-default_version = '1.1'
+default_version = '1.2'
module_pathname = '$libdir/fuzzystrmatch'
relocatable = true
trusted = true
diff --git a/contrib/fuzzystrmatch/meson.build b/contrib/fuzzystrmatch/meson.build
index 11aec733cb..abb944faaf 100644
--- a/contrib/fuzzystrmatch/meson.build
+++ b/contrib/fuzzystrmatch/meson.build
@@ -1,9 +1,18 @@
# Copyright (c) 2022, PostgreSQL Global Development Group
fuzzystrmatch_sources = files(
- 'fuzzystrmatch.c',
+ 'daitch_mokotoff.c',
'dmetaphone.c',
+ 'fuzzystrmatch.c',
+)
+
+daitch_mokotoff_h = custom_target('daitch_mokotoff',
+ input: 'daitch_mokotoff_header.pl',
+ output: 'daitch_mokotoff.h',
+ command: [perl, '@INPUT@', '@OUTPUT@'],
)
+generated_sources += daitch_mokotoff_h
+fuzzystrmatch_sources += daitch_mokotoff_h
if host_system == 'windows'
fuzzystrmatch_sources += rc_lib_gen.process(win32ver_rc, extra_args: [
@@ -13,6 +22,7 @@ endif
fuzzystrmatch = shared_module('fuzzystrmatch',
fuzzystrmatch_sources,
+ include_directories: include_directories('.'),
kwargs: contrib_mod_args,
)
contrib_targets += fuzzystrmatch
@@ -21,6 +31,7 @@ install_data(
'fuzzystrmatch.control',
'fuzzystrmatch--1.0--1.1.sql',
'fuzzystrmatch--1.1.sql',
+ 'fuzzystrmatch--1.1--1.2.sql',
kwargs: contrib_data_args,
)
@@ -31,6 +42,7 @@ tests += {
'regress': {
'sql': [
'fuzzystrmatch',
+ 'fuzzystrmatch_utf8',
],
},
}
diff --git a/contrib/fuzzystrmatch/sql/fuzzystrmatch.sql b/contrib/fuzzystrmatch/sql/fuzzystrmatch.sql
index f05dc28ffb..db05c7d6b6 100644
--- a/contrib/fuzzystrmatch/sql/fuzzystrmatch.sql
+++ b/contrib/fuzzystrmatch/sql/fuzzystrmatch.sql
@@ -19,3 +19,48 @@ SELECT metaphone('GUMBO', 4);
SELECT dmetaphone('gumbo');
SELECT dmetaphone_alt('gumbo');
+
+-- Wovels
+SELECT daitch_mokotoff('Augsburg');
+SELECT daitch_mokotoff('Breuer');
+SELECT daitch_mokotoff('Freud');
+
+-- The letter "H"
+SELECT daitch_mokotoff('Halberstadt');
+SELECT daitch_mokotoff('Mannheim');
+
+-- Adjacent sounds
+SELECT daitch_mokotoff('Chernowitz');
+
+-- Adjacent letters with identical adjacent code digits
+SELECT daitch_mokotoff('Cherkassy');
+SELECT daitch_mokotoff('Kleinman');
+
+-- More than one word
+SELECT daitch_mokotoff('Nowy Targ');
+
+-- Padded with "0"
+SELECT daitch_mokotoff('Berlin');
+
+-- Other examples from https://www.avotaynu.com/soundex.htm
+SELECT daitch_mokotoff('Ceniow');
+SELECT daitch_mokotoff('Tsenyuv');
+SELECT daitch_mokotoff('Holubica');
+SELECT daitch_mokotoff('Golubitsa');
+SELECT daitch_mokotoff('Przemysl');
+SELECT daitch_mokotoff('Pshemeshil');
+SELECT daitch_mokotoff('Rosochowaciec');
+SELECT daitch_mokotoff('Rosokhovatsets');
+
+-- Ignored characters
+SELECT daitch_mokotoff('''OBrien');
+SELECT daitch_mokotoff('O''Brien');
+
+-- "Difficult" cases, likely to cause trouble for other implementations.
+SELECT daitch_mokotoff('CJC');
+SELECT daitch_mokotoff('BESST');
+SELECT daitch_mokotoff('BOUEY');
+SELECT daitch_mokotoff('HANNMANN');
+SELECT daitch_mokotoff('MCCOYJR');
+SELECT daitch_mokotoff('ACCURSO');
+SELECT daitch_mokotoff('BIERSCHBACH');
diff --git a/contrib/fuzzystrmatch/sql/fuzzystrmatch_utf8.sql b/contrib/fuzzystrmatch/sql/fuzzystrmatch_utf8.sql
new file mode 100644
index 0000000000..f42c01a1bb
--- /dev/null
+++ b/contrib/fuzzystrmatch/sql/fuzzystrmatch_utf8.sql
@@ -0,0 +1,26 @@
+/*
+ * This test must be run in a database with UTF-8 encoding,
+ * because other encodings don't support all the characters used.
+ */
+
+SELECT getdatabaseencoding() <> 'UTF8'
+ AS skip_test \gset
+\if :skip_test
+\quit
+\endif
+
+set client_encoding = utf8;
+
+-- CREATE EXTENSION IF NOT EXISTS fuzzystrmatch;
+
+-- Accents
+SELECT daitch_mokotoff('Müller');
+SELECT daitch_mokotoff('Schäfer');
+SELECT daitch_mokotoff('Straßburg');
+SELECT daitch_mokotoff('Éregon');
+
+-- Special characters added at https://www.jewishgen.org/InfoFiles/Soundex.html
+SELECT daitch_mokotoff('gąszczu');
+SELECT daitch_mokotoff('brzęczy');
+SELECT daitch_mokotoff('ţamas');
+SELECT daitch_mokotoff('țamas');
diff --git a/doc/src/sgml/fuzzystrmatch.sgml b/doc/src/sgml/fuzzystrmatch.sgml
index 382e54be91..95814b9901 100644
--- a/doc/src/sgml/fuzzystrmatch.sgml
+++ b/doc/src/sgml/fuzzystrmatch.sgml
@@ -241,4 +241,99 @@ test=# SELECT dmetaphone('gumbo');
</screen>
</sect2>
+ <sect2>
+ <title>Daitch-Mokotoff Soundex</title>
+
+ <para>
+ Compared to the American Soundex System implemented in the
+ <function>soundex</function> function, the major improvements of the
+ Daitch-Mokotoff Soundex System are:
+
+ <itemizedlist spacing="compact" mark="bullet">
+ <listitem>
+ <para>
+ Information is coded to the first six meaningful letters rather than
+ four.
+ </para>
+ </listitem>
+ <listitem>
+ <para>
+ The initial letter is coded rather than kept as is.
+ </para>
+ </listitem>
+ <listitem>
+ <para>
+ Where two consecutive letters have a single sound, they are coded as a
+ single number.
+ </para>
+ </listitem>
+ <listitem>
+ <para>
+ When a letter or combination of letters may have two different sounds,
+ it is double coded under the two different codes.
+ </para>
+ </listitem>
+ <listitem>
+ <para>
+ A letter or combination of letters maps into ten possible codes rather
+ than seven.
+ </para>
+ </listitem>
+ </itemizedlist>
+ </para>
+
+ <indexterm>
+ <primary>daitch_mokotoff</primary>
+ </indexterm>
+
+ <para>
+ The following function generates Daitch-Mokotoff soundex codes for matching
+ of similar-sounding input:
+ </para>
+
+<synopsis>
+daitch_mokotoff(text source) returns text[]
+</synopsis>
+
+ <para>
+ Since a Daitch-Mokotoff soundex code consists of only 6 digits,
+ <literal>source</literal> should be preferably a single word or name.
+ The returned text array may be used directly in a GIN index, using the
+ <literal>&&</literal> operator for matching, see <xref linkend="gin"/>.
+ For more advanced queries, Full Text Search may be used, see
+ <xref linkend="textsearch"/>, and the example below.
+ </para>
+
+ <para>
+ Example:
+ </para>
+
+<programlisting>
+CREATE OR REPLACE FUNCTION soundex_tsvector(v_name text) RETURNS tsvector AS $$
+ SELECT to_tsvector('simple', string_agg(array_to_string(daitch_mokotoff(n), ' '), ' '))
+ FROM regexp_split_to_table(v_name, '\s+') AS n
+$$ LANGUAGE sql STRICT IMMUTABLE PARALLEL SAFE;
+
+CREATE OR REPLACE FUNCTION soundex_tsquery(v_name text) RETURNS tsquery AS $$
+ SELECT string_agg('(' || array_to_string(daitch_mokotoff(n), '|') || ')', '&')::tsquery
+ FROM regexp_split_to_table(v_name, '\s+') AS n
+$$ LANGUAGE sql STRICT IMMUTABLE PARALLEL SAFE;
+
+-- Note that searches could be more efficient with the tsvector in a separate column
+-- (no recalculation on table row recheck).
+CREATE TABLE s (nm text);
+CREATE INDEX ix_s_txt ON s USING gin (soundex_tsvector(nm)) WITH (fastupdate = off);
+
+INSERT INTO s VALUES ('John Doe');
+INSERT INTO s VALUES ('Jane Roe');
+INSERT INTO s VALUES ('Public John Q.');
+INSERT INTO s VALUES ('George Best');
+
+SELECT * FROM s WHERE soundex_tsvector(nm) @@ soundex_tsquery('john');
+SELECT * FROM s WHERE soundex_tsvector(nm) @@ soundex_tsquery('jane doe');
+SELECT * FROM s WHERE soundex_tsvector(nm) @@ soundex_tsquery('john public');
+SELECT * FROM s WHERE soundex_tsvector(nm) @@ soundex_tsquery('besst, giorgio');
+</programlisting>
+ </sect2>
+
</sect1>
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