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Optimize LIKE with turbo-boyer-more algoritm

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This commit is contained in:
monty@hundin.mysql.fi
2002-05-17 16:45:00 +03:00
parent 0c5c517db6
commit ce1353a454
6 changed files with 321 additions and 6 deletions
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27
sql/item_cmpfunc.h
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@ -478,15 +478,40 @@ public:
class Item_func_like :public Item_bool_func2
{
char escape;
// Turbo Boyer-Moore data
bool canDoTurboBM; // pattern is '%abcd%' case
const char* pattern;
int pattern_len;
// TurboBM buffers, *this is owner
int* bmGs; // good suffix shift table, size is pattern_len + 1
int* bmBc; // bad character shift table, size is alphabet_size
void turboBM_compute_suffixes(int* suff);
void turboBM_compute_good_suffix_shifts(int* suff);
void turboBM_compute_bad_character_shifts();
bool turboBM_matches(const char* text, int text_len) const;
enum { alphabet_size = 256 };
public:
Item_func_like(Item *a,Item *b, char* escape_arg) :Item_bool_func2(a,b),escape(*escape_arg)
Item_func_like::Item_func_like(Item *a,Item *b, char* escape_arg) :
Item_bool_func2(a,b),
escape(*escape_arg),
canDoTurboBM(false),
pattern(0),
pattern_len(0),
bmGs(0),
bmBc(0)
{}
longlong val_int();
enum Functype functype() const { return LIKE_FUNC; }
optimize_type select_optimize() const;
cond_result eq_cmp_result() const { return COND_TRUE; }
const char *func_name() const { return "like"; }
void fix_length_and_dec();
bool fix_fields(THD *thd,struct st_table_list *tlist);
};
#ifdef USE_REGEX