upstream/postgresql
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2026-04-15 22:10:45 -04:00
Code Issues Projects Releases Packages Wiki Activity Actions

Optimize sorting and deduplicating trigrams

Browse source 
Use templated qsort() so that the comparison function can be
inlined. To speed up qunique(), use a specialized comparison function
that only checks for equality.

Author: David Geier <geidav.pg@gmail.com>
Reviewed-by: Kirill Reshke <reshkekirill@gmail.com>
Discussion: https://www.postgresql.org/message-id/2a76b5ef-4b12-4023-93a1-eed6e64968f3@gmail.com
This commit is contained in:
Heikki Linnakangas 2026-04-07 14:11:25 +03:00
parent 884f9b3c76
commit 9f3755ea07
1 changed files with 53 additions and 10 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

63
contrib/pg_trgm/trgm_op.c
View file

@ -226,6 +226,55 @@ CMPTRGM_CHOOSE(const void *a, const void *b)
return CMPTRGM(a, b);
}
#define ST_SORT trigram_qsort_signed
#define ST_ELEMENT_TYPE_VOID
#define ST_COMPARE(a, b) CMPTRGM_SIGNED(a, b)
#define ST_SCOPE static
#define ST_DEFINE
#define ST_DECLARE
#include "lib/sort_template.h"
#define ST_SORT trigram_qsort_unsigned
#define ST_ELEMENT_TYPE_VOID
#define ST_COMPARE(a, b) CMPTRGM_UNSIGNED(a, b)
#define ST_SCOPE static
#define ST_DEFINE
#define ST_DECLARE
#include "lib/sort_template.h"
/* Sort an array of trigrams, handling signedess correctly */
static void
trigram_qsort(trgm *array, size_t n)
{
if (GetDefaultCharSignedness())
trigram_qsort_signed(array, n, sizeof(trgm));
else
trigram_qsort_unsigned(array, n, sizeof(trgm));
}
/*
* Compare two trigrams for equality. This has the same signature as
* comparison functions used for sorting, so that this can be used with
* qunique(). This doesn't need separate versions for "signed char" and "
* unsigned char" because equality is the same for both.
*/
static inline int
CMPTRGM_EQ(const void *a, const void *b)
{
char *aa = (char *) a;
char *bb = (char *) b;
return aa[0] != bb[0] || aa[1] != bb[1] || aa[2] != bb[2] ? 1 : 0;
}
/* Deduplicate an array of trigrams */
static size_t
trigram_qunique(trgm *array, size_t n)
{
return qunique(array, n, sizeof(trgm), CMPTRGM_EQ);
}
/*
* Deprecated function.
* Use "pg_trgm.similarity_threshold" GUC variable instead of this function.
@ -281,12 +330,6 @@ show_limit(PG_FUNCTION_ARGS)
PG_RETURN_FLOAT4(similarity_threshold);
}
static int
comp_trgm(const void *a, const void *b)
{
return CMPTRGM(a, b);
}
/*
* Finds first word in string, returns pointer to the word,
* endword points to the character after word
@ -569,8 +612,8 @@ generate_trgm(char *str, int slen)
*/
if (len > 1)
{
qsort(GETARR(trg), len, sizeof(trgm), comp_trgm);
len = qunique(GETARR(trg), len, sizeof(trgm), comp_trgm);
trigram_qsort(GETARR(trg), len);
len = trigram_qunique(GETARR(trg), len);
}
SET_VARSIZE(trg, CALCGTSIZE(ARRKEY, len));
@ -1100,8 +1143,8 @@ generate_wildcard_trgm(const char *str, int slen)
len = arr.length;
if (len > 1)
{
qsort(GETARR(trg), len, sizeof(trgm), comp_trgm);
len = qunique(GETARR(trg), len, sizeof(trgm), comp_trgm);
trigram_qsort(GETARR(trg), len);
len = trigram_qunique(GETARR(trg), len);
}
trg->flag = ARRKEY;