diff options
Diffstat (limited to 'sql/sql_select.cc')
| -rw-r--r-- | sql/sql_select.cc | 154 |
1 files changed, 103 insertions, 51 deletions
diff --git a/sql/sql_select.cc b/sql/sql_select.cc index 01b21dd7e2d..1d19ba7e96e 100644 --- a/sql/sql_select.cc +++ b/sql/sql_select.cc @@ -9119,18 +9119,26 @@ optimize_cond(JOIN *join, COND *conds, List<TABLE_LIST> *join_list, /** - Remove const and eq items. + Handles the reqursive job for remove_eq_conds() - @return - Return new item, or NULL if no condition @n - cond_value is set to according: - - COND_OK : query is possible (field = constant) - - COND_TRUE : always true ( 1 = 1 ) - - COND_FALSE : always false ( 1 = 2 ) + Remove const and eq items. Return new item, or NULL if no condition + cond_value is set to according: + COND_OK query is possible (field = constant) + COND_TRUE always true ( 1 = 1 ) + COND_FALSE always false ( 1 = 2 ) + + SYNPOSIS + remove_eq_conds() + thd THD environment + cond the condition to handle + cond_value the resulting value of the condition + + RETURN + *COND with the simplified condition */ -COND * -remove_eq_conds(THD *thd, COND *cond, Item::cond_result *cond_value) +static COND * +internal_remove_eq_conds(THD *thd, COND *cond, Item::cond_result *cond_value) { if (cond->type() == Item::COND_ITEM) { @@ -9144,7 +9152,7 @@ remove_eq_conds(THD *thd, COND *cond, Item::cond_result *cond_value) Item *item; while ((item=li++)) { - Item *new_item=remove_eq_conds(thd, item, &tmp_cond_value); + Item *new_item=internal_remove_eq_conds(thd, item, &tmp_cond_value); if (!new_item) li.remove(); else if (item != new_item) @@ -9193,6 +9201,86 @@ remove_eq_conds(THD *thd, COND *cond, Item::cond_result *cond_value) else if (cond->type() == Item::FUNC_ITEM && ((Item_func*) cond)->functype() == Item_func::ISNULL_FUNC) { + Item_func_isnull *func=(Item_func_isnull*) cond; + Item **args= func->arguments(); + if (args[0]->type() == Item::FIELD_ITEM) + { + Field *field=((Item_field*) args[0])->field; + /* fix to replace 'NULL' dates with '0' (shreeve@uci.edu) */ + /* + datetime_field IS NULL has to be modified to + datetime_field == 0 + */ + if (((field->type() == MYSQL_TYPE_DATE) || + (field->type() == MYSQL_TYPE_DATETIME)) && + (field->flags & NOT_NULL_FLAG) && !field->table->maybe_null) + { + COND *new_cond; + if ((new_cond= new Item_func_eq(args[0],new Item_int("0", 0, 2)))) + { + cond=new_cond; + /* + Item_func_eq can't be fixed after creation so we do not check + cond->fixed, also it do not need tables so we use 0 as second + argument. + */ + cond->fix_fields(thd, &cond); + } + } + } + if (cond->const_item()) + { + *cond_value= eval_const_cond(cond) ? Item::COND_TRUE : Item::COND_FALSE; + return (COND*) 0; + } + } + else if (cond->const_item()) + { + *cond_value= eval_const_cond(cond) ? Item::COND_TRUE : Item::COND_FALSE; + return (COND*) 0; + } + else if ((*cond_value= cond->eq_cmp_result()) != Item::COND_OK) + { // boolan compare function + Item *left_item= ((Item_func*) cond)->arguments()[0]; + Item *right_item= ((Item_func*) cond)->arguments()[1]; + if (left_item->eq(right_item,1)) + { + if (!left_item->maybe_null || + ((Item_func*) cond)->functype() == Item_func::EQUAL_FUNC) + return (COND*) 0; // Compare of identical items + } + } + *cond_value=Item::COND_OK; + return cond; // Point at next and level +} + + +/** + Remove const and eq items. Return new item, or NULL if no condition + cond_value is set to according: + COND_OK query is possible (field = constant) + COND_TRUE always true ( 1 = 1 ) + COND_FALSE always false ( 1 = 2 ) + + SYNPOSIS + remove_eq_conds() + thd THD environment + cond the condition to handle + cond_value the resulting value of the condition + + NOTES + calls the inner_remove_eq_conds to check all the tree reqursively + + RETURN + *COND with the simplified condition +*/ + +COND * +remove_eq_conds(THD *thd, COND *cond, Item::cond_result *cond_value) +{ + if (cond->type() == Item::FUNC_ITEM && + ((Item_func*) cond)->functype() == Item_func::ISNULL_FUNC) + { /* Handles this special case for some ODBC applications: The are requesting the row that was just updated with a auto_increment @@ -9235,52 +9323,16 @@ remove_eq_conds(THD *thd, COND *cond, Item::cond_result *cond_value) clear for next row */ thd->substitute_null_with_insert_id= FALSE; + + *cond_value= Item::COND_OK; + return cond; } - /* fix to replace 'NULL' dates with '0' (shreeve@uci.edu) */ - else if (((field->type() == MYSQL_TYPE_DATE) || - (field->type() == MYSQL_TYPE_DATETIME)) && - (field->flags & NOT_NULL_FLAG) && - !field->table->maybe_null) - { - COND *new_cond; - if ((new_cond= new Item_func_eq(args[0],new Item_int("0", 0, 2)))) - { - cond=new_cond; - /* - Item_func_eq can't be fixed after creation so we do not check - cond->fixed, also it do not need tables so we use 0 as second - argument. - */ - cond->fix_fields(thd, &cond); - } - } - } - if (cond->const_item()) - { - *cond_value= eval_const_cond(cond) ? Item::COND_TRUE : Item::COND_FALSE; - return (COND*) 0; - } - } - else if (cond->const_item()) - { - *cond_value= eval_const_cond(cond) ? Item::COND_TRUE : Item::COND_FALSE; - return (COND*) 0; - } - else if ((*cond_value= cond->eq_cmp_result()) != Item::COND_OK) - { // boolan compare function - Item *left_item= ((Item_func*) cond)->arguments()[0]; - Item *right_item= ((Item_func*) cond)->arguments()[1]; - if (left_item->eq(right_item,1)) - { - if (!left_item->maybe_null || - ((Item_func*) cond)->functype() == Item_func::EQUAL_FUNC) - return (COND*) 0; // Compare of identical items } } - *cond_value=Item::COND_OK; - return cond; // Point at next and level + return internal_remove_eq_conds(thd, cond, cond_value); // Scan all the condition } + /* Check if equality can be used in removing components of GROUP BY/DISTINCT |