From: Teodor Sigaev Date: Wed, 16 Mar 2016 15:59:21 +0000 (+0300) Subject: Add word_similarity to pg_trgm contrib module. X-Git-Tag: REL9_6_BETA1~473 X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=f576b17cd;p=postgresql Add word_similarity to pg_trgm contrib module. Patch introduces a concept of similarity over string and just a word from another string. Version of extension is not changed because 1.2 was already introduced in 9.6 release cycle, so, there wasn't a public version. Author: Alexander Korotkov, Artur Zakirov --- diff --git a/contrib/pg_trgm/Makefile b/contrib/pg_trgm/Makefile index 1e38753622..c0c78f3459 100644 --- a/contrib/pg_trgm/Makefile +++ b/contrib/pg_trgm/Makefile @@ -7,7 +7,7 @@ EXTENSION = pg_trgm DATA = pg_trgm--1.2.sql pg_trgm--1.0--1.1.sql pg_trgm--1.1--1.2.sql pg_trgm--unpackaged--1.0.sql PGFILEDESC = "pg_trgm - trigram matching" -REGRESS = pg_trgm +REGRESS = pg_trgm pg_word_trgm ifdef USE_PGXS PG_CONFIG = pg_config diff --git a/contrib/pg_trgm/expected/pg_trgm.out b/contrib/pg_trgm/expected/pg_trgm.out index 13b1fde1b8..78e8174f86 100644 --- a/contrib/pg_trgm/expected/pg_trgm.out +++ b/contrib/pg_trgm/expected/pg_trgm.out @@ -59,7 +59,7 @@ select similarity('---', '####---'); 0 (1 row) -CREATE TABLE test_trgm(t text); +CREATE TABLE test_trgm(t text COLLATE "C"); \copy test_trgm from 'data/trgm.data' select t,similarity(t,'qwertyu0988') as sml from test_trgm where t % 'qwertyu0988' order by sml desc, t; t | sml @@ -3467,7 +3467,7 @@ select t,similarity(t,'gwertyu1988') as sml from test_trgm where t % 'gwertyu198 qwertyu0988 | 0.333333 (1 row) -create table test2(t text); +create table test2(t text COLLATE "C"); insert into test2 values ('abcdef'); insert into test2 values ('quark'); insert into test2 values (' z foo bar'); diff --git a/contrib/pg_trgm/pg_trgm--1.1--1.2.sql b/contrib/pg_trgm/pg_trgm--1.1--1.2.sql index c101f21061..ff0f13fd08 100644 --- a/contrib/pg_trgm/pg_trgm--1.1--1.2.sql +++ b/contrib/pg_trgm/pg_trgm--1.1--1.2.sql @@ -3,10 +3,72 @@ -- complain if script is sourced in psql, rather than via ALTER EXTENSION \echo Use "ALTER EXTENSION pg_trgm UPDATE TO '1.2'" to load this file. \quit +CREATE FUNCTION word_similarity(text,text) +RETURNS float4 +AS 'MODULE_PATHNAME' +LANGUAGE C STRICT IMMUTABLE; + +CREATE FUNCTION word_similarity_op(text,text) +RETURNS bool +AS 'MODULE_PATHNAME' +LANGUAGE C STRICT STABLE; -- stable because depends on pg_trgm.word_similarity_threshold + +CREATE FUNCTION word_similarity_commutator_op(text,text) +RETURNS bool +AS 'MODULE_PATHNAME' +LANGUAGE C STRICT STABLE; -- stable because depends on pg_trgm.word_similarity_threshold + +CREATE FUNCTION word_similarity_dist_op(text,text) +RETURNS float4 +AS 'MODULE_PATHNAME' +LANGUAGE C STRICT IMMUTABLE; + +CREATE FUNCTION word_similarity_dist_commutator_op(text,text) +RETURNS float4 +AS 'MODULE_PATHNAME' +LANGUAGE C STRICT IMMUTABLE; + +CREATE OPERATOR <% ( + LEFTARG = text, + RIGHTARG = text, + PROCEDURE = word_similarity_op, + COMMUTATOR = '%>', + RESTRICT = contsel, + JOIN = contjoinsel +); + +CREATE OPERATOR %> ( + LEFTARG = text, + RIGHTARG = text, + PROCEDURE = word_similarity_commutator_op, + COMMUTATOR = '<%', + RESTRICT = contsel, + JOIN = contjoinsel +); + +CREATE OPERATOR <<-> ( + LEFTARG = text, + RIGHTARG = text, + PROCEDURE = word_similarity_dist_op, + COMMUTATOR = '<->>' +); + +CREATE OPERATOR <->> ( + LEFTARG = text, + RIGHTARG = text, + PROCEDURE = word_similarity_dist_commutator_op, + COMMUTATOR = '<<->' +); + CREATE FUNCTION gin_trgm_triconsistent(internal, int2, text, int4, internal, internal, internal) RETURNS "char" AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT; +ALTER OPERATOR FAMILY gist_trgm_ops USING gist ADD + OPERATOR 7 %> (text, text), + OPERATOR 8 <->> (text, text) FOR ORDER BY pg_catalog.float_ops; + ALTER OPERATOR FAMILY gin_trgm_ops USING gin ADD - FUNCTION 6 (text, text) gin_trgm_triconsistent (internal, int2, text, int4, internal, internal, internal); + OPERATOR 7 %> (text, text), + FUNCTION 6 (text, text) gin_trgm_triconsistent (internal, int2, text, int4, internal, internal, internal); diff --git a/contrib/pg_trgm/pg_trgm--1.2.sql b/contrib/pg_trgm/pg_trgm--1.2.sql index 5ee115ecdc..bc23dfe0f3 100644 --- a/contrib/pg_trgm/pg_trgm--1.2.sql +++ b/contrib/pg_trgm/pg_trgm--1.2.sql @@ -39,6 +39,39 @@ CREATE OPERATOR % ( JOIN = contjoinsel ); +CREATE FUNCTION word_similarity(text,text) +RETURNS float4 +AS 'MODULE_PATHNAME' +LANGUAGE C STRICT IMMUTABLE; + +CREATE FUNCTION word_similarity_op(text,text) +RETURNS bool +AS 'MODULE_PATHNAME' +LANGUAGE C STRICT STABLE; -- stable because depends on pg_trgm.word_similarity_threshold + +CREATE FUNCTION word_similarity_commutator_op(text,text) +RETURNS bool +AS 'MODULE_PATHNAME' +LANGUAGE C STRICT STABLE; -- stable because depends on pg_trgm.word_similarity_threshold + +CREATE OPERATOR <% ( + LEFTARG = text, + RIGHTARG = text, + PROCEDURE = word_similarity_op, + COMMUTATOR = '%>', + RESTRICT = contsel, + JOIN = contjoinsel +); + +CREATE OPERATOR %> ( + LEFTARG = text, + RIGHTARG = text, + PROCEDURE = word_similarity_commutator_op, + COMMUTATOR = '<%', + RESTRICT = contsel, + JOIN = contjoinsel +); + CREATE FUNCTION similarity_dist(text,text) RETURNS float4 AS 'MODULE_PATHNAME' @@ -51,6 +84,30 @@ CREATE OPERATOR <-> ( COMMUTATOR = '<->' ); +CREATE FUNCTION word_similarity_dist_op(text,text) +RETURNS float4 +AS 'MODULE_PATHNAME' +LANGUAGE C STRICT IMMUTABLE; + +CREATE FUNCTION word_similarity_dist_commutator_op(text,text) +RETURNS float4 +AS 'MODULE_PATHNAME' +LANGUAGE C STRICT IMMUTABLE; + +CREATE OPERATOR <<-> ( + LEFTARG = text, + RIGHTARG = text, + PROCEDURE = word_similarity_dist_op, + COMMUTATOR = '<->>' +); + +CREATE OPERATOR <->> ( + LEFTARG = text, + RIGHTARG = text, + PROCEDURE = word_similarity_dist_commutator_op, + COMMUTATOR = '<<->' +); + -- gist key CREATE FUNCTION gtrgm_in(cstring) RETURNS gtrgm @@ -140,6 +197,12 @@ ALTER OPERATOR FAMILY gist_trgm_ops USING gist ADD OPERATOR 5 pg_catalog.~ (text, text), OPERATOR 6 pg_catalog.~* (text, text); +-- Add operators that are new in 9.6 (pg_trgm 1.2). + +ALTER OPERATOR FAMILY gist_trgm_ops USING gist ADD + OPERATOR 7 %> (text, text), + OPERATOR 8 <->> (text, text) FOR ORDER BY pg_catalog.float_ops; + -- support functions for gin CREATE FUNCTION gin_extract_value_trgm(text, internal) RETURNS internal @@ -187,4 +250,5 @@ AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT; ALTER OPERATOR FAMILY gin_trgm_ops USING gin ADD + OPERATOR 7 %> (text, text), FUNCTION 6 (text,text) gin_trgm_triconsistent (internal, int2, text, int4, internal, internal, internal); diff --git a/contrib/pg_trgm/sql/pg_trgm.sql b/contrib/pg_trgm/sql/pg_trgm.sql index 7b02d98818..6cefc8e643 100644 --- a/contrib/pg_trgm/sql/pg_trgm.sql +++ b/contrib/pg_trgm/sql/pg_trgm.sql @@ -13,7 +13,7 @@ select similarity('wow',' WOW '); select similarity('---', '####---'); -CREATE TABLE test_trgm(t text); +CREATE TABLE test_trgm(t text COLLATE "C"); \copy test_trgm from 'data/trgm.data' @@ -40,7 +40,7 @@ select t,similarity(t,'qwertyu0988') as sml from test_trgm where t % 'qwertyu098 select t,similarity(t,'gwertyu0988') as sml from test_trgm where t % 'gwertyu0988' order by sml desc, t; select t,similarity(t,'gwertyu1988') as sml from test_trgm where t % 'gwertyu1988' order by sml desc, t; -create table test2(t text); +create table test2(t text COLLATE "C"); insert into test2 values ('abcdef'); insert into test2 values ('quark'); insert into test2 values (' z foo bar'); diff --git a/contrib/pg_trgm/trgm.h b/contrib/pg_trgm/trgm.h index 046cf58e13..8cd88e763c 100644 --- a/contrib/pg_trgm/trgm.h +++ b/contrib/pg_trgm/trgm.h @@ -26,13 +26,14 @@ #define DIVUNION /* operator strategy numbers */ -#define SimilarityStrategyNumber 1 -#define DistanceStrategyNumber 2 -#define LikeStrategyNumber 3 -#define ILikeStrategyNumber 4 -#define RegExpStrategyNumber 5 -#define RegExpICaseStrategyNumber 6 - +#define SimilarityStrategyNumber 1 +#define DistanceStrategyNumber 2 +#define LikeStrategyNumber 3 +#define ILikeStrategyNumber 4 +#define RegExpStrategyNumber 5 +#define RegExpICaseStrategyNumber 6 +#define WordSimilarityStrategyNumber 7 +#define WordDistanceStrategyNumber 8 typedef char trgm[3]; @@ -103,15 +104,28 @@ typedef char *BITVECP; #define GETARR(x) ( (trgm*)( (char*)x+TRGMHDRSIZE ) ) #define ARRNELEM(x) ( ( VARSIZE(x) - TRGMHDRSIZE )/sizeof(trgm) ) +/* + * If DIVUNION is defined then similarity formula is: + * count / (len1 + len2 - count) + * else if DIVUNION is not defined then similarity formula is: + * count / max(len1, len2) + */ +#ifdef DIVUNION +#define CALCSML(count, len1, len2) ((float4) (count)) / ((float4) ((len1) + (len2) - (count))) +#else +#define CALCSML(count, len1, len2) ((float4) (count)) / ((float4) (((len1) > (len2)) ? (len1) : (len2))) +#endif + typedef struct TrgmPackedGraph TrgmPackedGraph; extern double similarity_threshold; +extern double word_similarity_threshold; extern uint32 trgm2int(trgm *ptr); extern void compact_trigram(trgm *tptr, char *str, int bytelen); extern TRGM *generate_trgm(char *str, int slen); extern TRGM *generate_wildcard_trgm(const char *str, int slen); -extern float4 cnt_sml(TRGM *trg1, TRGM *trg2); +extern float4 cnt_sml(TRGM *trg1, TRGM *trg2, bool inexact); extern bool trgm_contained_by(TRGM *trg1, TRGM *trg2); extern bool *trgm_presence_map(TRGM *query, TRGM *key); extern TRGM *createTrgmNFA(text *text_re, Oid collation, diff --git a/contrib/pg_trgm/trgm_gin.c b/contrib/pg_trgm/trgm_gin.c index ea8edef67a..6805e3e9b2 100644 --- a/contrib/pg_trgm/trgm_gin.c +++ b/contrib/pg_trgm/trgm_gin.c @@ -89,6 +89,7 @@ gin_extract_query_trgm(PG_FUNCTION_ARGS) switch (strategy) { case SimilarityStrategyNumber: + case WordSimilarityStrategyNumber: trg = generate_trgm(VARDATA(val), VARSIZE(val) - VARHDRSZ); break; case ILikeStrategyNumber: @@ -176,6 +177,7 @@ gin_trgm_consistent(PG_FUNCTION_ARGS) bool res; int32 i, ntrue; + double nlimit; /* All cases served by this function are inexact */ *recheck = true; @@ -183,6 +185,10 @@ gin_trgm_consistent(PG_FUNCTION_ARGS) switch (strategy) { case SimilarityStrategyNumber: + case WordSimilarityStrategyNumber: + nlimit = (strategy == SimilarityStrategyNumber) ? + similarity_threshold : word_similarity_threshold; + /* Count the matches */ ntrue = 0; for (i = 0; i < nkeys; i++) @@ -207,8 +213,7 @@ gin_trgm_consistent(PG_FUNCTION_ARGS) * So, independly on DIVUNION the upper bound formula is the same. */ res = (nkeys == 0) ? false : - ((((((float4) ntrue) / ((float4) nkeys))) >= similarity_threshold) - ? true : false); + (((((float4) ntrue) / ((float4) nkeys))) >= nlimit); break; case ILikeStrategyNumber: #ifndef IGNORECASE @@ -270,10 +275,15 @@ gin_trgm_triconsistent(PG_FUNCTION_ARGS) int32 i, ntrue; bool *boolcheck; + double nlimit; switch (strategy) { case SimilarityStrategyNumber: + case WordSimilarityStrategyNumber: + nlimit = (strategy == SimilarityStrategyNumber) ? + similarity_threshold : word_similarity_threshold; + /* Count the matches */ ntrue = 0; for (i = 0; i < nkeys; i++) @@ -285,9 +295,9 @@ gin_trgm_triconsistent(PG_FUNCTION_ARGS) /* * See comment in gin_trgm_consistent() about * upper bound formula */ - res = (nkeys == 0) ? GIN_FALSE : - (((((float4) ntrue) / ((float4) nkeys)) >= similarity_threshold) - ? GIN_MAYBE : GIN_FALSE); + res = (nkeys == 0) + ? GIN_FALSE : (((((float4) ntrue) / ((float4) nkeys)) >= nlimit) + ? GIN_MAYBE : GIN_FALSE); break; case ILikeStrategyNumber: #ifndef IGNORECASE diff --git a/contrib/pg_trgm/trgm_gist.c b/contrib/pg_trgm/trgm_gist.c index cbd89586cd..2181c2623f 100644 --- a/contrib/pg_trgm/trgm_gist.c +++ b/contrib/pg_trgm/trgm_gist.c @@ -191,6 +191,7 @@ gtrgm_consistent(PG_FUNCTION_ARGS) bool res; Size querysize = VARSIZE(query); gtrgm_consistent_cache *cache; + double nlimit; /* * We keep the extracted trigrams in cache, because trigram extraction is @@ -218,6 +219,7 @@ gtrgm_consistent(PG_FUNCTION_ARGS) switch (strategy) { case SimilarityStrategyNumber: + case WordSimilarityStrategyNumber: qtrg = generate_trgm(VARDATA(query), querysize - VARHDRSZ); break; @@ -286,16 +288,23 @@ gtrgm_consistent(PG_FUNCTION_ARGS) switch (strategy) { case SimilarityStrategyNumber: - /* Similarity search is exact */ - *recheck = false; + case WordSimilarityStrategyNumber: + /* Similarity search is exact. Word similarity search is inexact */ + *recheck = (strategy == WordSimilarityStrategyNumber); + nlimit = (strategy == SimilarityStrategyNumber) ? + similarity_threshold : word_similarity_threshold; if (GIST_LEAF(entry)) { /* all leafs contains orig trgm */ - float4 tmpsml = cnt_sml(key, qtrg); + /* + * Prevent gcc optimizing the tmpsml variable using volatile + * keyword. Otherwise comparison of nlimit and tmpsml may give + * wrong results. + */ + float4 volatile tmpsml = cnt_sml(qtrg, key, *recheck); /* strange bug at freebsd 5.2.1 and gcc 3.3.3 */ - res = (*(int *) &tmpsml == *(int *) &similarity_threshold - || tmpsml > similarity_threshold) ? true : false; + res = (*(int *) &tmpsml == *(int *) &nlimit || tmpsml > nlimit); } else if (ISALLTRUE(key)) { /* non-leaf contains signature */ @@ -309,8 +318,7 @@ gtrgm_consistent(PG_FUNCTION_ARGS) if (len == 0) res = false; else - res = (((((float8) count) / ((float8) len))) >= similarity_threshold) - ? true : false; + res = (((((float8) count) / ((float8) len))) >= nlimit); } break; case ILikeStrategyNumber: @@ -428,6 +436,7 @@ gtrgm_distance(PG_FUNCTION_ARGS) StrategyNumber strategy = (StrategyNumber) PG_GETARG_UINT16(2); /* Oid subtype = PG_GETARG_OID(3); */ + bool *recheck = (bool *) PG_GETARG_POINTER(4); TRGM *key = (TRGM *) DatumGetPointer(entry->key); TRGM *qtrg; float8 res; @@ -463,9 +472,17 @@ gtrgm_distance(PG_FUNCTION_ARGS) switch (strategy) { case DistanceStrategyNumber: + case WordDistanceStrategyNumber: + *recheck = strategy == WordDistanceStrategyNumber; if (GIST_LEAF(entry)) { /* all leafs contains orig trgm */ - res = 1.0 - cnt_sml(key, qtrg); + /* + * Prevent gcc optimizing the sml variable using volatile + * keyword. Otherwise res can differ from the + * word_similarity_dist_op() function. + */ + float4 volatile sml = cnt_sml(qtrg, key, *recheck); + res = 1.0 - sml; } else if (ISALLTRUE(key)) { /* all leafs contains orig trgm */ diff --git a/contrib/pg_trgm/trgm_op.c b/contrib/pg_trgm/trgm_op.c index b2c1f6b061..eaf20e4515 100644 --- a/contrib/pg_trgm/trgm_op.c +++ b/contrib/pg_trgm/trgm_op.c @@ -15,7 +15,8 @@ PG_MODULE_MAGIC; /* GUC variables */ -double similarity_threshold = 0.3f; +double similarity_threshold = 0.3f; +double word_similarity_threshold = 0.6f; void _PG_init(void); @@ -23,8 +24,20 @@ PG_FUNCTION_INFO_V1(set_limit); PG_FUNCTION_INFO_V1(show_limit); PG_FUNCTION_INFO_V1(show_trgm); PG_FUNCTION_INFO_V1(similarity); +PG_FUNCTION_INFO_V1(word_similarity); PG_FUNCTION_INFO_V1(similarity_dist); PG_FUNCTION_INFO_V1(similarity_op); +PG_FUNCTION_INFO_V1(word_similarity_op); +PG_FUNCTION_INFO_V1(word_similarity_commutator_op); +PG_FUNCTION_INFO_V1(word_similarity_dist_op); +PG_FUNCTION_INFO_V1(word_similarity_dist_commutator_op); + +/* Trigram with position */ +typedef struct +{ + trgm trg; + int index; +} pos_trgm; /* * Module load callback @@ -45,11 +58,23 @@ _PG_init(void) NULL, NULL, NULL); + DefineCustomRealVariable("pg_trgm.word_similarity_threshold", + "Sets the threshold used by the <%% operator.", + "Valid range is 0.0 .. 1.0.", + &word_similarity_threshold, + 0.6, + 0.0, + 1.0, + PGC_USERSET, + 0, + NULL, + NULL, + NULL); } /* * Deprecated function. - * Use "pg_trgm.similarity_threshold" GUC variable instead of this function + * Use "pg_trgm.similarity_threshold" GUC variable instead of this function. */ Datum set_limit(PG_FUNCTION_ARGS) @@ -59,14 +84,14 @@ set_limit(PG_FUNCTION_ARGS) if (nlimit < 0 || nlimit > 1.0) ereport(ERROR, (errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE), - errmsg("wrong limit, should be between 0 and 1"))); + errmsg("wrong threshold, should be between 0 and 1"))); similarity_threshold = nlimit; PG_RETURN_FLOAT4(similarity_threshold); } /* * Deprecated function. - * Use "pg_trgm.similarity_threshold" GUC variable instead of this function + * Use "pg_trgm.similarity_threshold" GUC variable instead of this function. */ Datum show_limit(PG_FUNCTION_ARGS) @@ -199,38 +224,28 @@ make_trigrams(trgm *tptr, char *str, int bytelen, int charlen) return tptr; } -TRGM * -generate_trgm(char *str, int slen) +/* + * Make array of trigrams without sorting and removing duplicate items. + * + * trg: where to return the array of trigrams. + * str: source string, of length slen bytes. + * + * Returns length of the generated array. + */ +static int +generate_trgm_only(trgm *trg, char *str, int slen) { - TRGM *trg; - char *buf; trgm *tptr; - int len, - charlen, + char *buf; + int charlen, bytelen; char *bword, *eword; - /* - * Guard against possible overflow in the palloc requests below. (We - * don't worry about the additive constants, since palloc can detect - * requests that are a little above MaxAllocSize --- we just need to - * prevent integer overflow in the multiplications.) - */ - if ((Size) (slen / 2) >= (MaxAllocSize / (sizeof(trgm) * 3)) || - (Size) slen >= (MaxAllocSize / pg_database_encoding_max_length())) - ereport(ERROR, - (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED), - errmsg("out of memory"))); - - trg = (TRGM *) palloc(TRGMHDRSIZE + sizeof(trgm) * (slen / 2 + 1) *3); - trg->flag = ARRKEY; - SET_VARSIZE(trg, TRGMHDRSIZE); - if (slen + LPADDING + RPADDING < 3 || slen == 0) - return trg; + return 0; - tptr = GETARR(trg); + tptr = trg; /* Allocate a buffer for case-folded, blank-padded words */ buf = (char *) palloc(slen * pg_database_encoding_max_length() + 4); @@ -270,7 +285,47 @@ generate_trgm(char *str, int slen) pfree(buf); - if ((len = tptr - GETARR(trg)) == 0) + return tptr - trg; +} + +/* + * Guard against possible overflow in the palloc requests below. (We + * don't worry about the additive constants, since palloc can detect + * requests that are a little above MaxAllocSize --- we just need to + * prevent integer overflow in the multiplications.) + */ +static void +protect_out_of_mem(int slen) +{ + if ((Size) (slen / 2) >= (MaxAllocSize / (sizeof(trgm) * 3)) || + (Size) slen >= (MaxAllocSize / pg_database_encoding_max_length())) + ereport(ERROR, + (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED), + errmsg("out of memory"))); +} + +/* + * Make array of trigrams with sorting and removing duplicate items. + * + * str: source string, of length slen bytes. + * + * Returns the sorted array of unique trigrams. + */ +TRGM * +generate_trgm(char *str, int slen) +{ + TRGM *trg; + int len; + + protect_out_of_mem(slen); + + trg = (TRGM *) palloc(TRGMHDRSIZE + sizeof(trgm) * (slen / 2 + 1) *3); + trg->flag = ARRKEY; + + len = generate_trgm_only(GETARR(trg), str, slen); + SET_VARSIZE(trg, CALCGTSIZE(ARRKEY, len)); + + if (len == 0) return trg; /* @@ -287,6 +342,285 @@ generate_trgm(char *str, int slen) return trg; } +/* + * Make array of positional trigrams from two trigram arrays trg1 and trg2. + * + * trg1: trigram array of search pattern, of length len1. trg1 is required + * word which positions don't matter and replaced with -1. + * trg2: trigram array of text, of length len2. trg2 is haystack where we + * search and have to store its positions. + * + * Returns concatenated trigram array. + */ +static pos_trgm * +make_positional_trgm(trgm *trg1, int len1, trgm *trg2, int len2) +{ + pos_trgm *result; + int i, len = len1 + len2; + + result = (pos_trgm *) palloc(sizeof(pos_trgm) * len); + + for (i = 0; i < len1; i++) + { + memcpy(&result[i].trg, &trg1[i], sizeof(trgm)); + result[i].index = -1; + } + + for (i = 0; i < len2; i++) + { + memcpy(&result[i + len1].trg, &trg2[i], sizeof(trgm)); + result[i + len1].index = i; + } + + return result; +} + +/* + * Compare position trigrams: compare trigrams first and position second. + */ +static int +comp_ptrgm(const void *v1, const void *v2) +{ + const pos_trgm *p1 = (const pos_trgm *)v1; + const pos_trgm *p2 = (const pos_trgm *)v2; + int cmp; + + cmp = CMPTRGM(p1->trg, p2->trg); + if (cmp != 0) + return cmp; + + if (p1->index < p2->index) + return -1; + else if (p1->index == p2->index) + return 0; + else + return 1; +} + +/* + * Iterative search function which calculates maximum similarity with word in + * the string. But maximum similarity is calculated only if check_only == false. + * + * trg2indexes: array which stores indexes of the array "found". + * found: array which stores true of false values. + * ulen1: count of unique trigrams of array "trg1". + * len2: length of array "trg2" and array "trg2indexes". + * len: length of the array "found". + * check_only: if true then only check existaince of similar search pattern in + * text. + * + * Returns word similarity. + */ +static float4 +iterate_word_similarity(int *trg2indexes, + bool *found, + int ulen1, + int len2, + int len, + bool check_only) +{ + int *lastpos, + i, + ulen2 = 0, + count = 0, + upper = -1, + lower = -1; + float4 smlr_cur, + smlr_max = 0.0f; + + /* Memorise last position of each trigram */ + lastpos = (int *) palloc(sizeof(int) * len); + memset(lastpos, -1, sizeof(int) * len); + + for (i = 0; i < len2; i++) + { + /* Get index of next trigram */ + int trgindex = trg2indexes[i]; + + /* Update last position of this trigram */ + if (lower >= 0 || found[trgindex]) + { + if (lastpos[trgindex] < 0) + { + ulen2++; + if (found[trgindex]) + count++; + } + lastpos[trgindex] = i; + } + + /* Adjust lower bound if this trigram is present in required substing */ + if (found[trgindex]) + { + int prev_lower, + tmp_ulen2, + tmp_lower, + tmp_count; + + upper = i; + if (lower == -1) + { + lower = i; + ulen2 = 1; + } + + smlr_cur = CALCSML(count, ulen1, ulen2); + + /* Also try to adjust upper bound for greater similarity */ + tmp_count = count; + tmp_ulen2 = ulen2; + prev_lower = lower; + for (tmp_lower = lower; tmp_lower <= upper; tmp_lower++) + { + float smlr_tmp = CALCSML(tmp_count, ulen1, tmp_ulen2); + int tmp_trgindex; + + if (smlr_tmp > smlr_cur) + { + smlr_cur = smlr_tmp; + ulen2 = tmp_ulen2; + lower = tmp_lower; + count = tmp_count; + } + /* + * if we only check that word similarity is greater than + * pg_trgm.word_similarity_threshold we do not need to calculate + * a maximum similarity. + */ + if (check_only && smlr_cur >= word_similarity_threshold) + break; + + tmp_trgindex = trg2indexes[tmp_lower]; + if (lastpos[tmp_trgindex] == tmp_lower) + { + tmp_ulen2--; + if (found[tmp_trgindex]) + tmp_count--; + } + } + + smlr_max = Max(smlr_max, smlr_cur); + /* + * if we only check that word similarity is greater than + * pg_trgm.word_similarity_threshold we do not need to calculate a + * maximum similarity + */ + if (check_only && smlr_max >= word_similarity_threshold) + break; + + for (tmp_lower = prev_lower; tmp_lower < lower; tmp_lower++) + { + int tmp_trgindex; + tmp_trgindex = trg2indexes[tmp_lower]; + if (lastpos[tmp_trgindex] == tmp_lower) + lastpos[tmp_trgindex] = -1; + } + } + } + + pfree(lastpos); + + return smlr_max; +} + +/* + * Calculate word similarity. + * This function prepare two arrays: "trg2indexes" and "found". Then this arrays + * are used to calculate word similarity using iterate_word_similarity(). + * + * "trg2indexes" is array which stores indexes of the array "found". + * In other words: + * trg2indexes[j] = i; + * found[i] = true (or false); + * If found[i] == true then there is trigram trg2[j] in array "trg1". + * If found[i] == false then there is not trigram trg2[j] in array "trg1". + * + * str1: search pattern string, of length slen1 bytes. + * str2: text in which we are looking for a word, of length slen2 bytes. + * check_only: if true then only check existaince of similar search pattern in + * text. + * + * Returns word similarity. + */ +static float4 +calc_word_similarity(char *str1, int slen1, char *str2, int slen2, + bool check_only) +{ + bool *found; + pos_trgm *ptrg; + trgm *trg1; + trgm *trg2; + int len1, + len2, + len, + i, + j, + ulen1; + int *trg2indexes; + float4 result; + + protect_out_of_mem(slen1 + slen2); + + /* Make positional trigrams */ + trg1 = (trgm *) palloc(sizeof(trgm) * (slen1 / 2 + 1) * 3); + trg2 = (trgm *) palloc(sizeof(trgm) * (slen2 / 2 + 1) * 3); + + len1 = generate_trgm_only(trg1, str1, slen1); + len2 = generate_trgm_only(trg2, str2, slen2); + + ptrg = make_positional_trgm(trg1, len1, trg2, len2); + len = len1 + len2; + qsort(ptrg, len, sizeof(pos_trgm), comp_ptrgm); + + pfree(trg1); + pfree(trg2); + + /* + * Merge positional trigrams array: enumerate each trigram and find its + * presence in required word. + */ + trg2indexes = (int *) palloc(sizeof(int) * len2); + found = (bool *) palloc0(sizeof(bool) * len); + + ulen1 = 0; + j = 0; + for (i = 0; i < len; i++) + { + if (i > 0) + { + int cmp = CMPTRGM(ptrg[i - 1].trg, ptrg[i].trg); + if (cmp != 0) + { + if (found[j]) + ulen1++; + j++; + } + } + + if (ptrg[i].index >= 0) + { + trg2indexes[ptrg[i].index] = j; + } + else + { + found[j] = true; + } + } + if (found[j]) + ulen1++; + + /* Run iterative procedure to find maximum similarity with word */ + result = iterate_word_similarity(trg2indexes, found, ulen1, len2, len, + check_only); + + pfree(trg2indexes); + pfree(found); + pfree(ptrg); + + return result; +} + + /* * Extract the next non-wildcard part of a search string, ie, a word bounded * by '_' or '%' meta-characters, non-word characters or string end. @@ -459,17 +793,7 @@ generate_wildcard_trgm(const char *str, int slen) bytelen; const char *eword; - /* - * Guard against possible overflow in the palloc requests below. (We - * don't worry about the additive constants, since palloc can detect - * requests that are a little above MaxAllocSize --- we just need to - * prevent integer overflow in the multiplications.) - */ - if ((Size) (slen / 2) >= (MaxAllocSize / (sizeof(trgm) * 3)) || - (Size) slen >= (MaxAllocSize / pg_database_encoding_max_length())) - ereport(ERROR, - (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED), - errmsg("out of memory"))); + protect_out_of_mem(slen); trg = (TRGM *) palloc(TRGMHDRSIZE + sizeof(trgm) * (slen / 2 + 1) *3); trg->flag = ARRKEY; @@ -590,7 +914,7 @@ show_trgm(PG_FUNCTION_ARGS) } float4 -cnt_sml(TRGM *trg1, TRGM *trg2) +cnt_sml(TRGM *trg1, TRGM *trg2, bool inexact) { trgm *ptr1, *ptr2; @@ -624,14 +948,15 @@ cnt_sml(TRGM *trg1, TRGM *trg2) } } -#ifdef DIVUNION - return ((float4) count) / ((float4) (len1 + len2 - count)); -#else - return ((float4) count) / ((float4) ((len1 > len2) ? len1 : len2)); -#endif - + /* + * If inexact then len2 is equal to count, because we don't know actual + * length of second string in inexact search and we can assume that count + * is a lower bound of len2. + */ + return CALCSML(count, len1, inexact ? count : len2); } + /* * Returns whether trg2 contains all trigrams in trg1. * This relies on the trigram arrays being sorted. @@ -726,7 +1051,7 @@ similarity(PG_FUNCTION_ARGS) trg1 = generate_trgm(VARDATA(in1), VARSIZE(in1) - VARHDRSZ); trg2 = generate_trgm(VARDATA(in2), VARSIZE(in2) - VARHDRSZ); - res = cnt_sml(trg1, trg2); + res = cnt_sml(trg1, trg2, false); pfree(trg1); pfree(trg2); @@ -736,6 +1061,22 @@ similarity(PG_FUNCTION_ARGS) PG_RETURN_FLOAT4(res); } +Datum +word_similarity(PG_FUNCTION_ARGS) +{ + text *in1 = PG_GETARG_TEXT_PP(0); + text *in2 = PG_GETARG_TEXT_PP(1); + float4 res; + + res = calc_word_similarity(VARDATA_ANY(in1), VARSIZE_ANY_EXHDR(in1), + VARDATA_ANY(in2), VARSIZE_ANY_EXHDR(in2), + false); + + PG_FREE_IF_COPY(in1, 0); + PG_FREE_IF_COPY(in2, 1); + PG_RETURN_FLOAT4(res); +} + Datum similarity_dist(PG_FUNCTION_ARGS) { @@ -755,3 +1096,67 @@ similarity_op(PG_FUNCTION_ARGS) PG_RETURN_BOOL(res >= similarity_threshold); } + +Datum +word_similarity_op(PG_FUNCTION_ARGS) +{ + text *in1 = PG_GETARG_TEXT_PP(0); + text *in2 = PG_GETARG_TEXT_PP(1); + float4 res; + + res = calc_word_similarity(VARDATA_ANY(in1), VARSIZE_ANY_EXHDR(in1), + VARDATA_ANY(in2), VARSIZE_ANY_EXHDR(in2), + true); + + PG_FREE_IF_COPY(in1, 0); + PG_FREE_IF_COPY(in2, 1); + PG_RETURN_BOOL(res >= word_similarity_threshold); +} + +Datum +word_similarity_commutator_op(PG_FUNCTION_ARGS) +{ + text *in1 = PG_GETARG_TEXT_PP(0); + text *in2 = PG_GETARG_TEXT_PP(1); + float4 res; + + res = calc_word_similarity(VARDATA_ANY(in2), VARSIZE_ANY_EXHDR(in2), + VARDATA_ANY(in1), VARSIZE_ANY_EXHDR(in1), + true); + + PG_FREE_IF_COPY(in1, 0); + PG_FREE_IF_COPY(in2, 1); + PG_RETURN_BOOL(res >= word_similarity_threshold); +} + +Datum +word_similarity_dist_op(PG_FUNCTION_ARGS) +{ + text *in1 = PG_GETARG_TEXT_PP(0); + text *in2 = PG_GETARG_TEXT_PP(1); + float4 res; + + res = calc_word_similarity(VARDATA_ANY(in1), VARSIZE_ANY_EXHDR(in1), + VARDATA_ANY(in2), VARSIZE_ANY_EXHDR(in2), + false); + + PG_FREE_IF_COPY(in1, 0); + PG_FREE_IF_COPY(in2, 1); + PG_RETURN_FLOAT4(1.0 - res); +} + +Datum +word_similarity_dist_commutator_op(PG_FUNCTION_ARGS) +{ + text *in1 = PG_GETARG_TEXT_PP(0); + text *in2 = PG_GETARG_TEXT_PP(1); + float4 res; + + res = calc_word_similarity(VARDATA_ANY(in2), VARSIZE_ANY_EXHDR(in2), + VARDATA_ANY(in1), VARSIZE_ANY_EXHDR(in1), + false); + + PG_FREE_IF_COPY(in1, 0); + PG_FREE_IF_COPY(in2, 1); + PG_RETURN_FLOAT4(1.0 - res); +} diff --git a/doc/src/sgml/pgtrgm.sgml b/doc/src/sgml/pgtrgm.sgml index 1a9b5a796f..cdce17251f 100644 --- a/doc/src/sgml/pgtrgm.sgml +++ b/doc/src/sgml/pgtrgm.sgml @@ -92,6 +92,21 @@ (In practice this is seldom useful except for debugging.) + + + word_similarity(text, text) + word_similarity + + real + + Returns a number that indicates how similar the first string + to the most similar word of the second string. The function searches in + the second string a most similar word not a most similar substring. The + range of the result is zero (indicating that the two strings are + completely dissimilar) to one (indicating that the first string is + identical to one of the word of the second string). + + show_limit()show_limit real @@ -137,6 +152,16 @@ pg_trgm.similarity_threshold. + + text %> text + boolean + + Returns true if its first argument has the similar word in + the second argument and they have a similarity that is greater than the + current word similarity threshold set by + pg_trgm.word_similarity_threshold parameter. + + text <-> text real @@ -145,6 +170,16 @@ one minus the similarity() value. + + + text <->> text + + real + + Returns the distance between the arguments, that is + one minus the word_similarity() value. + + @@ -168,6 +203,23 @@ + + + pg_trgm.word_similarity_threshold (real) + + + pg_trgm.word_similarity_threshold configuration parameter + + + + + + Sets the current word similarity threshold that is used by + the %> operator. The threshold must be between + 0 and 1 (default is 0.6). + + + @@ -225,6 +277,33 @@ SELECT t, t <-> 'word' AS dist a small number of the closest matches is wanted. + + Also you can use an index on the t column for word + similarity. For example: + +SELECT t, word_similarity('word', t) AS sml + FROM test_trgm + WHERE t %> 'word' + ORDER BY sml DESC, t; + + This will return all values in the text column that have a word + which sufficiently similar to word, sorted from best + match to worst. The index will be used to make this a fast operation + even over very large data sets. + + + + A variant of the above query is + +SELECT t, t <->> 'word' AS dist + FROM test_trgm + ORDER BY dist LIMIT 10; + + This can be implemented quite efficiently by GiST indexes, but not + by GIN indexes. + + + Beginning in PostgreSQL 9.1, these index types also support index searches for LIKE and ILIKE, for example