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Support LIKE and ILIKE index searches via contrib/pg_trgm indexes.

Browse Source 
Unlike Btree-based LIKE optimization, this works for non-left-anchored
search patterns.  The effectiveness of the search depends on how many
trigrams can be extracted from the pattern.  (The worst case, with no
trigrams, degrades to a full-table scan, so this isn't a panacea.  But
it can be very useful.)

Alexander Korotkov, reviewed by Jan Urbanski
This commit is contained in:
Tom Lane
2011-01-31 21:33:55 -05:00
parent 6238473adb
commit 6e2f3ae884
9 changed files with 639 additions and 49 deletions
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90
contrib/pg_trgm/expected/pg_trgm.out
View File

@@ -3467,3 +3467,93 @@ select t,similarity(t,'gwertyu1988') as sml from test_trgm where t % 'gwertyu198
qwertyu0988 | 0.333333
(1 row)
create table test2(t text);
insert into test2 values ('abcdef');
insert into test2 values ('quark');
create index test2_idx_gin on test2 using gin (t gin_trgm_ops);
set enable_seqscan=off;
explain (costs off)
select * from test2 where t like '%BCD%';
QUERY PLAN
------------------------------------------
Bitmap Heap Scan on test2
Recheck Cond: (t ~~ '%BCD%'::text)
-> Bitmap Index Scan on test2_idx_gin
Index Cond: (t ~~ '%BCD%'::text)
(4 rows)
explain (costs off)
select * from test2 where t ilike '%BCD%';
QUERY PLAN
-------------------------------------------
Bitmap Heap Scan on test2
Recheck Cond: (t ~~* '%BCD%'::text)
-> Bitmap Index Scan on test2_idx_gin
Index Cond: (t ~~* '%BCD%'::text)
(4 rows)
select * from test2 where t like '%BCD%';
t
---
(0 rows)
select * from test2 where t like '%bcd%';
t
--------
abcdef
(1 row)
select * from test2 where t ilike '%BCD%';
t
--------
abcdef
(1 row)
select * from test2 where t ilike 'qua%';
t
-------
quark
(1 row)
drop index test2_idx_gin;
create index test2_idx_gist on test2 using gist (t gist_trgm_ops);
set enable_seqscan=off;
explain (costs off)
select * from test2 where t like '%BCD%';
QUERY PLAN
------------------------------------------
Index Scan using test2_idx_gist on test2
Index Cond: (t ~~ '%BCD%'::text)
(2 rows)
explain (costs off)
select * from test2 where t ilike '%BCD%';
QUERY PLAN
------------------------------------------
Index Scan using test2_idx_gist on test2
Index Cond: (t ~~* '%BCD%'::text)
(2 rows)
select * from test2 where t like '%BCD%';
t
---
(0 rows)
select * from test2 where t like '%bcd%';
t
--------
abcdef
(1 row)
select * from test2 where t ilike '%BCD%';
t
--------
abcdef
(1 row)
select * from test2 where t ilike 'qua%';
t
-------
quark
(1 row)

16
contrib/pg_trgm/pg_trgm.sql.in
View File

@@ -113,6 +113,8 @@ FOR TYPE text USING gist
AS
OPERATOR 1 % (text, text),
OPERATOR 2 <-> (text, text) FOR ORDER BY pg_catalog.float_ops,
OPERATOR 3 pg_catalog.~~ (text, text),
OPERATOR 4 pg_catalog.~~* (text, text),
FUNCTION 1 gtrgm_consistent (internal, text, int, oid, internal),
FUNCTION 2 gtrgm_union (bytea, internal),
FUNCTION 3 gtrgm_compress (internal),
@@ -124,17 +126,17 @@ AS
STORAGE gtrgm;
-- support functions for gin
CREATE OR REPLACE FUNCTION gin_extract_trgm(text, internal)
CREATE OR REPLACE FUNCTION gin_extract_value_trgm(text, internal)
RETURNS internal
AS 'MODULE_PATHNAME'
LANGUAGE C IMMUTABLE STRICT;
CREATE OR REPLACE FUNCTION gin_extract_trgm(text, internal, int2, internal, internal)
CREATE OR REPLACE FUNCTION gin_extract_query_trgm(text, internal, int2, internal, internal, internal, internal)
RETURNS internal
AS 'MODULE_PATHNAME'
LANGUAGE C IMMUTABLE STRICT;
CREATE OR REPLACE FUNCTION gin_trgm_consistent(internal, int2, text, int4, internal, internal)
CREATE OR REPLACE FUNCTION gin_trgm_consistent(internal, int2, text, int4, internal, internal, internal, internal)
RETURNS bool
AS 'MODULE_PATHNAME'
LANGUAGE C IMMUTABLE STRICT;
@@ -144,8 +146,10 @@ CREATE OPERATOR CLASS gin_trgm_ops
FOR TYPE text USING gin
AS
OPERATOR 1 % (text, text),
OPERATOR 3 pg_catalog.~~ (text, text),
OPERATOR 4 pg_catalog.~~* (text, text),
FUNCTION 1 btint4cmp (int4, int4),
FUNCTION 2 gin_extract_trgm (text, internal),
FUNCTION 3 gin_extract_trgm (text, internal, int2, internal, internal),
FUNCTION 4 gin_trgm_consistent (internal, int2, text, int4, internal, internal),
FUNCTION 2 gin_extract_value_trgm (text, internal),
FUNCTION 3 gin_extract_query_trgm (text, internal, int2, internal, internal, internal, internal),
FUNCTION 4 gin_trgm_consistent (internal, int2, text, int4, internal, internal, internal, internal),
STORAGE int4;

25
contrib/pg_trgm/sql/pg_trgm.sql
View File

@@ -45,3 +45,28 @@ set enable_seqscan=off;
select t,similarity(t,'qwertyu0988') as sml from test_trgm where t % 'qwertyu0988' order by sml desc, t;
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);
insert into test2 values ('abcdef');
insert into test2 values ('quark');
create index test2_idx_gin on test2 using gin (t gin_trgm_ops);
set enable_seqscan=off;
explain (costs off)
select * from test2 where t like '%BCD%';
explain (costs off)
select * from test2 where t ilike '%BCD%';
select * from test2 where t like '%BCD%';
select * from test2 where t like '%bcd%';
select * from test2 where t ilike '%BCD%';
select * from test2 where t ilike 'qua%';
drop index test2_idx_gin;
create index test2_idx_gist on test2 using gist (t gist_trgm_ops);
set enable_seqscan=off;
explain (costs off)
select * from test2 where t like '%BCD%';
explain (costs off)
select * from test2 where t ilike '%BCD%';
select * from test2 where t like '%BCD%';
select * from test2 where t like '%bcd%';
select * from test2 where t ilike '%BCD%';
select * from test2 where t ilike 'qua%';

22
contrib/pg_trgm/trgm.h
View File

@@ -13,12 +13,21 @@
#define LPADDING 2
#define RPADDING 1
#define KEEPONLYALNUM
/*
* Caution: IGNORECASE macro means that trigrams are case-insensitive.
* If this macro is disabled, the ~~* operator must be removed from the
* operator classes, because we can't handle case-insensitive wildcard search
* with case-sensitive trigrams. Failure to do this will result in "cannot
* handle ~~* with case-sensitive trigrams" errors.
*/
#define IGNORECASE
#define DIVUNION
/* operator strategy numbers */
#define SimilarityStrategyNumber 1
#define DistanceStrategyNumber 2
#define SimilarityStrategyNumber 1
#define DistanceStrategyNumber 2
#define LikeStrategyNumber 3
#define ILikeStrategyNumber 4
typedef char trgm[3];
@@ -40,7 +49,10 @@ uint32 trgm2int(trgm *ptr);
#else
#define ISPRINTABLECHAR(a) ( isascii( *(unsigned char*)(a) ) && isprint( *(unsigned char*)(a) ) )
#endif
#define ISPRINTABLETRGM(t) ( ISPRINTABLECHAR( ((char*)t) ) && ISPRINTABLECHAR( ((char*)t)+1 ) && ISPRINTABLECHAR( ((char*)t)+2 ) )
#define ISPRINTABLETRGM(t) ( ISPRINTABLECHAR( ((char*)(t)) ) && ISPRINTABLECHAR( ((char*)(t))+1 ) && ISPRINTABLECHAR( ((char*)(t))+2 ) )
#define ISESCAPECHAR(x) (*(x) == '\\') /* Wildcard escape character */
#define ISWILDCARDCHAR(x) (*(x) == '_' || *(x) == '%') /* Wildcard meta-character */
typedef struct
{
@@ -65,7 +77,7 @@ typedef char *BITVECP;
for(i=0;i<SIGLEN;i++)
#define GETBYTE(x,i) ( *( (BITVECP)(x) + (int)( (i) / BITBYTE ) ) )
#define GETBITBYTE(x,i) ( ((char)(x)) >> i & 0x01 )
#define GETBITBYTE(x,i) ( (((char)(x)) >> (i)) & 0x01 )
#define CLRBIT(x,i) GETBYTE(x,i) &= ~( 0x01 << ( (i) % BITBYTE ) )
#define SETBIT(x,i) GETBYTE(x,i) |= ( 0x01 << ( (i) % BITBYTE ) )
#define GETBIT(x,i) ( (GETBYTE(x,i) >> ( (i) % BITBYTE )) & 0x01 )
@@ -89,6 +101,8 @@ typedef char *BITVECP;
extern float4 trgm_limit;
TRGM *generate_trgm(char *str, int slen);
TRGM *generate_wildcard_trgm(const char *str, int slen);
float4 cnt_sml(TRGM *trg1, TRGM *trg2);
bool trgm_contained_by(TRGM *trg1, TRGM *trg2);
#endif /* __TRGM_H__ */

132
contrib/pg_trgm/trgm_gin.c
View File

@@ -7,6 +7,7 @@
#include "access/gin.h"
#include "access/itup.h"
#include "access/skey.h"
#include "access/tuptoaster.h"
#include "storage/bufpage.h"
#include "utils/array.h"
@@ -16,14 +17,31 @@
PG_FUNCTION_INFO_V1(gin_extract_trgm);
Datum gin_extract_trgm(PG_FUNCTION_ARGS);
PG_FUNCTION_INFO_V1(gin_extract_value_trgm);
Datum gin_extract_value_trgm(PG_FUNCTION_ARGS);
PG_FUNCTION_INFO_V1(gin_extract_query_trgm);
Datum gin_extract_query_trgm(PG_FUNCTION_ARGS);
PG_FUNCTION_INFO_V1(gin_trgm_consistent);
Datum gin_trgm_consistent(PG_FUNCTION_ARGS);
/*
* This function is used as both extractValue and extractQuery
* This function can only be called if a pre-9.1 version of the GIN operator
* class definition is present in the catalogs (probably as a consequence
* of upgrade-in-place). Complain.
*/
Datum
gin_extract_trgm(PG_FUNCTION_ARGS)
{
ereport(ERROR,
(errmsg("GIN operator class for pg_trgm is out of date"),
errhint("Please drop and re-create the pg_trgm catalog entries.")));
PG_RETURN_NULL();
}
Datum
gin_extract_value_trgm(PG_FUNCTION_ARGS)
{
text *val = (text *) PG_GETARG_TEXT_P(0);
int32 *nentries = (int32 *) PG_GETARG_POINTER(1);
@@ -57,34 +75,124 @@ gin_extract_trgm(PG_FUNCTION_ARGS)
PG_RETURN_POINTER(entries);
}
Datum
gin_extract_query_trgm(PG_FUNCTION_ARGS)
{
text *val = (text *) PG_GETARG_TEXT_P(0);
int32 *nentries = (int32 *) PG_GETARG_POINTER(1);
StrategyNumber strategy = PG_GETARG_UINT16(2);
/* bool **pmatch = (bool **) PG_GETARG_POINTER(3); */
/* Pointer *extra_data = (Pointer *) PG_GETARG_POINTER(4); */
/* bool **nullFlags = (bool **) PG_GETARG_POINTER(5); */
int32 *searchMode = (int32 *) PG_GETARG_POINTER(6);
Datum *entries = NULL;
TRGM *trg;
int32 trglen;
trgm *ptr;
int32 i;
switch (strategy)
{
case SimilarityStrategyNumber:
trg = generate_trgm(VARDATA(val), VARSIZE(val) - VARHDRSZ);
break;
case ILikeStrategyNumber:
#ifndef IGNORECASE
elog(ERROR, "cannot handle ~~* with case-sensitive trigrams");
#endif
/* FALL THRU */
case LikeStrategyNumber:
/*
* For wildcard search we extract all the trigrams that every
* potentially-matching string must include.
*/
trg = generate_wildcard_trgm(VARDATA(val), VARSIZE(val) - VARHDRSZ);
break;
default:
elog(ERROR, "unrecognized strategy number: %d", strategy);
trg = NULL; /* keep compiler quiet */
break;
}
trglen = ARRNELEM(trg);
*nentries = trglen;
if (trglen > 0)
{
entries = (Datum *) palloc(sizeof(Datum) * trglen);
ptr = GETARR(trg);
for (i = 0; i < trglen; i++)
{
int32 item = trgm2int(ptr);
entries[i] = Int32GetDatum(item);
ptr++;
}
}
/*
* If no trigram was extracted then we have to scan all the index.
*/
if (trglen == 0)
*searchMode = GIN_SEARCH_MODE_ALL;
PG_RETURN_POINTER(entries);
}
Datum
gin_trgm_consistent(PG_FUNCTION_ARGS)
{
bool *check = (bool *) PG_GETARG_POINTER(0);
/* StrategyNumber strategy = PG_GETARG_UINT16(1); */
StrategyNumber strategy = PG_GETARG_UINT16(1);
/* text *query = PG_GETARG_TEXT_P(2); */
int32 nkeys = PG_GETARG_INT32(3);
/* Pointer *extra_data = (Pointer *) PG_GETARG_POINTER(4); */
bool *recheck = (bool *) PG_GETARG_POINTER(5);
bool res = FALSE;
bool res;
int32 i,
ntrue = 0;
ntrue;
/* All cases served by this function are inexact */
*recheck = true;
/* Count the matches */
for (i = 0; i < nkeys; i++)
switch (strategy)
{
if (check[i])
ntrue++;
}
case SimilarityStrategyNumber:
/* Count the matches */
ntrue = 0;
for (i = 0; i < nkeys; i++)
{
if (check[i])
ntrue++;
}
#ifdef DIVUNION
res = (nkeys == ntrue) ? true : ((((((float4) ntrue) / ((float4) (nkeys - ntrue)))) >= trgm_limit) ? true : false);
res = (nkeys == ntrue) ? true : ((((((float4) ntrue) / ((float4) (nkeys - ntrue)))) >= trgm_limit) ? true : false);
#else
res = (nkeys == 0) ? false : ((((((float4) ntrue) / ((float4) nkeys))) >= trgm_limit) ? true : false);
res = (nkeys == 0) ? false : ((((((float4) ntrue) / ((float4) nkeys))) >= trgm_limit) ? true : false);
#endif
break;
case ILikeStrategyNumber:
#ifndef IGNORECASE
elog(ERROR, "cannot handle ~~* with case-sensitive trigrams");
#endif
/* FALL THRU */
case LikeStrategyNumber:
/* Check if all extracted trigrams are presented. */
res = true;
for (i = 0; i < nkeys; i++)
{
if (!check[i])
{
res = false;
break;
}
}
break;
default:
elog(ERROR, "unrecognized strategy number: %d", strategy);
res = false; /* keep compiler quiet */
break;
}
PG_RETURN_BOOL(res);
}

93
contrib/pg_trgm/trgm_gist.c
View File

@@ -195,31 +195,61 @@ gtrgm_consistent(PG_FUNCTION_ARGS)
TRGM *key = (TRGM *) DatumGetPointer(entry->key);
TRGM *qtrg;
bool res;
char *cache = (char *) fcinfo->flinfo->fn_extra;
char *cache = (char *) fcinfo->flinfo->fn_extra,
*cacheContents = cache + MAXALIGN(sizeof(StrategyNumber));
/* All cases served by this function are exact */
*recheck = false;
if (cache == NULL || VARSIZE(cache) != VARSIZE(query) || memcmp(cache, query, VARSIZE(query)) != 0)
/*
* Store both the strategy number and extracted trigrams in cache, because
* trigram extraction is relatively CPU-expensive. We must include
* strategy number because trigram extraction depends on strategy.
*/
if (cache == NULL || strategy != *((StrategyNumber *) cache) ||
VARSIZE(cacheContents) != VARSIZE(query) ||
memcmp(cacheContents, query, VARSIZE(query)) != 0)
{
qtrg = generate_trgm(VARDATA(query), VARSIZE(query) - VARHDRSZ);
switch (strategy)
{
case SimilarityStrategyNumber:
qtrg = generate_trgm(VARDATA(query), VARSIZE(query) - VARHDRSZ);
break;
case ILikeStrategyNumber:
#ifndef IGNORECASE
elog(ERROR, "cannot handle ~~* with case-sensitive trigrams");
#endif
/* FALL THRU */
case LikeStrategyNumber:
qtrg = generate_wildcard_trgm(VARDATA(query), VARSIZE(query) - VARHDRSZ);
break;
default:
elog(ERROR, "unrecognized strategy number: %d", strategy);
qtrg = NULL; /* keep compiler quiet */
break;
}
if (cache)
pfree(cache);
fcinfo->flinfo->fn_extra = MemoryContextAlloc(fcinfo->flinfo->fn_mcxt,
MAXALIGN(VARSIZE(query)) + VARSIZE(qtrg));
fcinfo->flinfo->fn_extra =
MemoryContextAlloc(fcinfo->flinfo->fn_mcxt,
MAXALIGN(sizeof(StrategyNumber)) +
MAXALIGN(VARSIZE(query)) +
VARSIZE(qtrg));
cache = (char *) fcinfo->flinfo->fn_extra;
cacheContents = cache + MAXALIGN(sizeof(StrategyNumber));
memcpy(cache, query, VARSIZE(query));
memcpy(cache + MAXALIGN(VARSIZE(query)), qtrg, VARSIZE(qtrg));
*((StrategyNumber *) cache) = strategy;
memcpy(cacheContents, query, VARSIZE(query));
memcpy(cacheContents + MAXALIGN(VARSIZE(query)), qtrg, VARSIZE(qtrg));
}
qtrg = (TRGM *) (cache + MAXALIGN(VARSIZE(query)));
qtrg = (TRGM *) (cacheContents + MAXALIGN(VARSIZE(query)));
switch (strategy)
{
case SimilarityStrategyNumber:
/* Similarity search is exact */
*recheck = false;
if (GIST_LEAF(entry))
{ /* all leafs contains orig trgm */
float4 tmpsml = cnt_sml(key, qtrg);
@@ -242,6 +272,47 @@ gtrgm_consistent(PG_FUNCTION_ARGS)
res = (((((float8) count) / ((float8) len))) >= trgm_limit) ? true : false;
}
break;
case ILikeStrategyNumber:
#ifndef IGNORECASE
elog(ERROR, "cannot handle ~~* with case-sensitive trigrams");
#endif
/* FALL THRU */
case LikeStrategyNumber:
/* Wildcard search is inexact */
*recheck = true;
/*
* Check if all the extracted trigrams can be present in child
* nodes.
*/
if (GIST_LEAF(entry))
{ /* all leafs contains orig trgm */
res = trgm_contained_by(qtrg, key);
}
else if (ISALLTRUE(key))
{ /* non-leaf contains signature */
res = true;
}
else
{ /* non-leaf contains signature */
int32 k,
tmp = 0,
len = ARRNELEM(qtrg);
trgm *ptr = GETARR(qtrg);
BITVECP sign = GETSIGN(key);
res = true;
for (k = 0; k < len; k++)
{
CPTRGM(((char *) &tmp), ptr + k);
if (!GETBIT(sign, HASHVAL(tmp)))
{
res = false;
break;
}
}
}
break;
default:
elog(ERROR, "unrecognized strategy number: %d", strategy);
res = false; /* keep compiler quiet */

286
contrib/pg_trgm/trgm_op.c
View File

@@ -18,6 +18,23 @@ float4 trgm_limit = 0.3f;
PG_FUNCTION_INFO_V1(set_limit);
Datum set_limit(PG_FUNCTION_ARGS);
PG_FUNCTION_INFO_V1(show_limit);
Datum show_limit(PG_FUNCTION_ARGS);
PG_FUNCTION_INFO_V1(show_trgm);
Datum show_trgm(PG_FUNCTION_ARGS);
PG_FUNCTION_INFO_V1(similarity);
Datum similarity(PG_FUNCTION_ARGS);
PG_FUNCTION_INFO_V1(similarity_dist);
Datum similarity_dist(PG_FUNCTION_ARGS);
PG_FUNCTION_INFO_V1(similarity_op);
Datum similarity_op(PG_FUNCTION_ARGS);
Datum
set_limit(PG_FUNCTION_ARGS)
{
@@ -29,8 +46,6 @@ set_limit(PG_FUNCTION_ARGS)
PG_RETURN_FLOAT4(trgm_limit);
}
PG_FUNCTION_INFO_V1(show_limit);
Datum show_limit(PG_FUNCTION_ARGS);
Datum
show_limit(PG_FUNCTION_ARGS)
{
@@ -120,7 +135,7 @@ cnt_trigram(trgm *tptr, char *str, int bytelen)
#endif
/*
* Adds trigramm from words (already padded).
* Adds trigrams from words (already padded).
*/
static trgm *
make_trigrams(trgm *tptr, char *str, int bytelen, int charlen)
@@ -236,6 +251,225 @@ generate_trgm(char *str, int slen)
return trg;
}
/*
* Extract the next non-wildcard part of a search string, ie, a word bounded
* by '_' or '%' meta-characters, non-word characters or string end.
*
* str: source string, of length lenstr bytes (need not be null-terminated)
* buf: where to return the substring (must be long enough)
* *bytelen: receives byte length of the found substring
* *charlen: receives character length of the found substring
*
* Returns pointer to end+1 of the found substring in the source string.
* Returns NULL if no word found (in which case buf, bytelen, charlen not set)
*
* If the found word is bounded by non-word characters or string boundaries
* then this function will include corresponding padding spaces into buf.
*/
static const char *
get_wildcard_part(const char *str, int lenstr,
char *buf, int *bytelen, int *charlen)
{
const char *beginword = str;
const char *endword;
char *s = buf;
bool in_wildcard_meta = false;
bool in_escape = false;
int clen;
/*
* Find the first word character remembering whether last character was
* wildcard meta-character.
*/
while (beginword - str < lenstr)
{
if (in_escape)
{
in_escape = false;
in_wildcard_meta = false;
if (iswordchr(beginword))
break;
}
else
{
if (ISESCAPECHAR(beginword))
in_escape = true;
else if (ISWILDCARDCHAR(beginword))
in_wildcard_meta = true;
else if (iswordchr(beginword))
break;
else
in_wildcard_meta = false;
}
beginword += pg_mblen(beginword);
}
/*
* Handle string end.
*/
if (beginword - str >= lenstr)
return NULL;
/*
* Add left padding spaces if last character wasn't wildcard
* meta-character.
*/
*charlen = 0;
if (!in_wildcard_meta)
{
if (LPADDING > 0)
{
*s++ = ' ';
(*charlen)++;
if (LPADDING > 1)
{
*s++ = ' ';
(*charlen)++;
}
}
}
/*
* Copy data into buf until wildcard meta-character, non-word character or
* string boundary. Strip escapes during copy.
*/
endword = beginword;
in_wildcard_meta = false;
in_escape = false;
while (endword - str < lenstr)
{
clen = pg_mblen(endword);
if (in_escape)
{
in_escape = false;
in_wildcard_meta = false;
if (iswordchr(endword))
{
memcpy(s, endword, clen);
(*charlen)++;
s += clen;
}
else
break;
}
else
{
if (ISESCAPECHAR(endword))
in_escape = true;
else if (ISWILDCARDCHAR(endword))
{
in_wildcard_meta = true;
break;
}
else if (iswordchr(endword))
{
memcpy(s, endword, clen);
(*charlen)++;
s += clen;
}
else
{
in_wildcard_meta = false;
break;
}
}
endword += clen;
}
/*
* Add right padding spaces if last character wasn't wildcard
* meta-character.
*/
if (!in_wildcard_meta)
{
if (RPADDING > 0)
{
*s++ = ' ';
(*charlen)++;
if (RPADDING > 1)
{
*s++ = ' ';
(*charlen)++;
}
}
}
*bytelen = s - buf;
return endword;
}
/*
* Generates trigrams for wildcard search string.
*
* Returns array of trigrams that must occur in any string that matches the
* wildcard string. For example, given pattern "a%bcd%" the trigrams
* " a", "bcd" would be extracted.
*/
TRGM *
generate_wildcard_trgm(const char *str, int slen)
{
TRGM *trg;
char *buf,
*buf2;
trgm *tptr;
int len,
charlen,
bytelen;
const char *eword;
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;
tptr = GETARR(trg);
buf = palloc(sizeof(char) * (slen + 4));
/*
* Extract trigrams from each substring extracted by get_wildcard_part.
*/
eword = str;
while ((eword = get_wildcard_part(eword, slen - (eword - str),
buf, &bytelen, &charlen)) != NULL)
{
#ifdef IGNORECASE
buf2 = lowerstr_with_len(buf, bytelen);
bytelen = strlen(buf2);
#else
buf2 = buf;
#endif
/*
* count trigrams
*/
tptr = make_trigrams(tptr, buf2, bytelen, charlen);
#ifdef IGNORECASE
pfree(buf2);
#endif
}
pfree(buf);
if ((len = tptr - GETARR(trg)) == 0)
return trg;
/*
* Make trigrams unique.
*/
if (len > 0)
{
qsort((void *) GETARR(trg), len, sizeof(trgm), comp_trgm);
len = unique_array(GETARR(trg), len);
}
SET_VARSIZE(trg, CALCGTSIZE(ARRKEY, len));
return trg;
}
uint32
trgm2int(trgm *ptr)
{
@@ -250,8 +484,6 @@ trgm2int(trgm *ptr)
return val;
}
PG_FUNCTION_INFO_V1(show_trgm);
Datum show_trgm(PG_FUNCTION_ARGS);
Datum
show_trgm(PG_FUNCTION_ARGS)
{
@@ -340,8 +572,44 @@ cnt_sml(TRGM *trg1, TRGM *trg2)
}
PG_FUNCTION_INFO_V1(similarity);
Datum similarity(PG_FUNCTION_ARGS);
/*
* Returns whether trg2 contains all trigrams in trg1.
* This relies on the trigram arrays being sorted.
*/
bool
trgm_contained_by(TRGM *trg1, TRGM *trg2)
{
trgm *ptr1,
*ptr2;
int len1,
len2;
ptr1 = GETARR(trg1);
ptr2 = GETARR(trg2);
len1 = ARRNELEM(trg1);
len2 = ARRNELEM(trg2);
while (ptr1 - GETARR(trg1) < len1 && ptr2 - GETARR(trg2) < len2)
{
int res = CMPTRGM(ptr1, ptr2);
if (res < 0)
return false;
else if (res > 0)
ptr2++;
else
{
ptr1++;
ptr2++;
}
}
if (ptr1 - GETARR(trg1) < len1)
return false;
else
return true;
}
Datum
similarity(PG_FUNCTION_ARGS)
{
@@ -364,8 +632,6 @@ similarity(PG_FUNCTION_ARGS)
PG_RETURN_FLOAT4(res);
}
PG_FUNCTION_INFO_V1(similarity_dist);
Datum similarity_dist(PG_FUNCTION_ARGS);
Datum
similarity_dist(PG_FUNCTION_ARGS)
{
@@ -375,8 +641,6 @@ similarity_dist(PG_FUNCTION_ARGS)
PG_RETURN_FLOAT4(1.0 - res);
}
PG_FUNCTION_INFO_V1(similarity_op);
Datum similarity_op(PG_FUNCTION_ARGS);
Datum
similarity_op(PG_FUNCTION_ARGS)
{

6
contrib/pg_trgm/uninstall_pg_trgm.sql
View File

@@ -25,11 +25,11 @@ DROP TYPE gtrgm CASCADE;
DROP OPERATOR CLASS gin_trgm_ops USING gin;
DROP FUNCTION gin_extract_trgm(text, internal);
DROP FUNCTION gin_extract_value_trgm(text, internal);
DROP FUNCTION gin_extract_trgm(text, internal, int2, internal, internal);
DROP FUNCTION gin_extract_query_trgm(text, internal, int2, internal, internal, internal, internal);
DROP FUNCTION gin_trgm_consistent(internal, int2, text, int4, internal, internal);
DROP FUNCTION gin_trgm_consistent(internal, int2, text, int4, internal, internal, internal, internal);
DROP OPERATOR % (text, text);