| 135 | */ |
| 136 | |
| 137 | bool foreign_key_prefix(Key *a, Key *b) |
| 138 | { |
| 139 | /* Ensure that 'a' is the generated key */ |
| 140 | if (a->generated) |
| 141 | { |
| 142 | if (b->generated && a->columns.elements > b->columns.elements) |
| 143 | swap_variables(Key*, a, b); // Put shorter key in 'a' |
| 144 | } |
| 145 | else |
| 146 | { |
| 147 | if (!b->generated) |
| 148 | return TRUE; // No foreign key |
| 149 | swap_variables(Key*, a, b); // Put generated key in 'a' |
| 150 | } |
| 151 | |
| 152 | /* Test if 'a' is a prefix of 'b' */ |
| 153 | if (a->columns.elements > b->columns.elements) |
| 154 | return TRUE; // Can't be prefix |
| 155 | |
| 156 | List_iterator<Key_part_spec> col_it1(a->columns); |
| 157 | List_iterator<Key_part_spec> col_it2(b->columns); |
| 158 | const Key_part_spec *col1, *col2; |
| 159 | |
| 160 | #ifdef ENABLE_WHEN_INNODB_CAN_HANDLE_SWAPED_FOREIGN_KEY_COLUMNS |
| 161 | while ((col1= col_it1++)) |
| 162 | { |
| 163 | bool found= 0; |
| 164 | col_it2.rewind(); |
| 165 | while ((col2= col_it2++)) |
| 166 | { |
| 167 | if (*col1 == *col2) |
| 168 | { |
| 169 | found= TRUE; |
| 170 | break; |
| 171 | } |
| 172 | } |
| 173 | if (!found) |
| 174 | return TRUE; // Error |
| 175 | } |
| 176 | return FALSE; // Is prefix |
| 177 | #else |
| 178 | while ((col1= col_it1++)) |
| 179 | { |
| 180 | col2= col_it2++; |
| 181 | if (!(*col1 == *col2)) |
| 182 | return TRUE; |
| 183 | } |
| 184 | return FALSE; // Is prefix |
| 185 | #endif |
| 186 | } |
| 187 | |
| 188 | |
| 189 | /**************************************************************************** |