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MDEV-35876 - speedup collation/charset lookup

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Replaces O(n) linear scans for collation lookups with O(1) hash lookups
to eliminate performance bottlenecks as collation counts grow.
This commit is contained in:
Jitesh Chawla 2025-03-09 19:39:27 +05:30 committed by Sergey Vojtovich
parent feb1cf9086
commit 543ebbcf8e
1 changed files with 29 additions and 11 deletions
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40
mysys/charset.c
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@ -30,6 +30,7 @@
#endif
static HASH charset_name_hash;
static HASH collation_name_hash;
/*
The code below implements this functionality:
@ -44,17 +45,9 @@ static HASH charset_name_hash;
static uint
get_collation_number_internal(const char *name)
{
CHARSET_INFO **cs;
for (cs= all_charsets;
cs < all_charsets + array_elements(all_charsets);
cs++)
{
if (cs[0] && cs[0]->coll_name.str &&
!my_strcasecmp_latin1(cs[0]->coll_name.str, name))
return cs[0]->number;
}
return 0;
CHARSET_INFO *cs= (CHARSET_INFO*) my_hash_search(&collation_name_hash,
(uchar*) name, strlen(name));
return cs ? cs->number : 0;
}
@ -805,6 +798,14 @@ static const uchar *get_charset_key(const void *object, size_t *size,
return (const uchar*) cs->cs_name.str;
}
static const uchar *get_collation_key(const void *object, size_t *length,
my_bool not_used __attribute__((unused)))
{
CHARSET_INFO *cs= (CHARSET_INFO*) object;
*length= cs->coll_name.length;
return (const uchar*) cs->coll_name.str;
}
static void init_available_charsets(void)
{
char fname[FN_REFLEN + sizeof(MY_CHARSET_INDEX)];
@ -819,6 +820,10 @@ static void init_available_charsets(void)
&my_charset_latin1, 64, 0, 0, get_charset_key,
0, 0, HASH_UNIQUE);
my_hash_init2(key_memory_charsets, &collation_name_hash, 16,
&my_charset_latin1, 64, 0, 0, get_collation_key,
0, 0, HASH_UNIQUE);
init_compiled_charsets(MYF(0));
/* Copy compiled charsets */
@ -839,6 +844,18 @@ static void init_available_charsets(void)
my_charset_loader_init_mysys(&loader);
strmov(get_charsets_dir(fname), MY_CHARSET_INDEX);
my_read_charset_file(&loader, fname, MYF(0));
/* Populate the collation_name_hash */
for (cs= (struct charset_info_st**) all_charsets;
cs < (struct charset_info_st**) all_charsets +
array_elements(all_charsets);
cs++)
{
CHARSET_INFO *c= *cs;
if (c && c->coll_name.str)
my_hash_insert(&collation_name_hash, (uchar*) c);
}
DBUG_VOID_RETURN;
}
@ -847,6 +864,7 @@ void free_charsets(void)
{
charsets_initialized= charsets_template;
my_hash_free(&charset_name_hash);
my_hash_free(&collation_name_hash);
}