diff options
Diffstat (limited to 'myisam/mi_search.c')
| -rw-r--r-- | myisam/mi_search.c | 47 |
1 files changed, 37 insertions, 10 deletions
diff --git a/myisam/mi_search.c b/myisam/mi_search.c index d57fd1bb5b2..41d53e76241 100644 --- a/myisam/mi_search.c +++ b/myisam/mi_search.c @@ -260,9 +260,11 @@ int _mi_prefix_search(MI_INFO *info, register MI_KEYDEF *keyinfo, uchar *page, uchar *key, uint key_len, uint nextflag, uchar **ret_pos, uchar *buff, my_bool *last_key) { - /* my_flag is raw comparison result to be changed according to - SEARCH_NO_FIND,SEARCH_LAST and HA_REVERSE_SORT flags. - flag is the value returned by _mi_key_cmp and as treated as final */ + /* + my_flag is raw comparison result to be changed according to + SEARCH_NO_FIND,SEARCH_LAST and HA_REVERSE_SORT flags. + flag is the value returned by _mi_key_cmp and as treated as final + */ int flag=0, my_flag=-1; uint nod_flag, length, len, matched, cmplen, kseg_len; uint prefix_len,suffix_len; @@ -695,13 +697,29 @@ static int compare_bin(uchar *a, uint a_length, uchar *b, uint b_length, } - /* - ** Compare two keys - ** Returns <0, 0, >0 acording to which is bigger - ** Key_length specifies length of key to use. Number-keys can't - ** be splited - ** If flag <> SEARCH_FIND compare also position - */ +/* + Compare two keys + + SYNOPSIS + _mi_key_cmp() + keyseg Key segments of key to compare + a First key to compare, in format from _mi_pack_key() + This is normally key specified by user + b Second key to compare. This is always from a row + key_length Length of key to compare. This can be shorter than + a to just compare sub keys + next_flag How keys should be compared + If bit SEARCH_FIND is not set the keys includes the row + position and this should also be compared + + NOTES + Number-keys can't be splited + + RETURN VALUES + <0 If a < b + 0 If a == b + >0 If a > b +*/ #define FCMP(A,B) ((int) (A) - (int) (B)) @@ -738,6 +756,15 @@ int _mi_key_cmp(register MI_KEYSEG *keyseg, register uchar *a, { if (nextflag == (SEARCH_FIND | SEARCH_UPDATE)) nextflag=SEARCH_SAME; /* Allow duplicate keys */ + else if (nextflag & SEARCH_NULL_ARE_NOT_EQUAL) + { + /* + This is only used from mi_check() to calculate cardinality. + It can't be used when searching for a key as this would cause + compare of (a,b) and (b,a) to return the same value. + */ + return -1; + } next_key_length=key_length; continue; /* To next key part */ } |