diff options
Diffstat (limited to 'sql/sql_select.cc')
| -rw-r--r-- | sql/sql_select.cc | 77 |
1 files changed, 50 insertions, 27 deletions
diff --git a/sql/sql_select.cc b/sql/sql_select.cc index c3b3fc5eaac..60c875f8f55 100644 --- a/sql/sql_select.cc +++ b/sql/sql_select.cc @@ -5038,8 +5038,23 @@ static void optimize_keyuse(JOIN *join, DYNAMIC_ARRAY *keyuse_array) Optionally (if out_args is supplied) will push the arguments of AGGFN(DISTINCT) to the list + Check for every COUNT(DISTINCT), AVG(DISTINCT) or + SUM(DISTINCT). These can be resolved by Loose Index Scan as long + as all the aggregate distinct functions refer to the same + fields. Thus: + + SELECT AGGFN(DISTINCT a, b), AGGFN(DISTINCT b, a)... => can use LIS + SELECT AGGFN(DISTINCT a), AGGFN(DISTINCT a) ... => can use LIS + SELECT AGGFN(DISTINCT a, b), AGGFN(DISTINCT a) ... => cannot use LIS + SELECT AGGFN(DISTINCT a), AGGFN(DISTINCT b) ... => cannot use LIS + etc. + @param join the join to check - @param[out] out_args list of aggregate function arguments + @param[out] out_args Collect the arguments of the aggregate functions + to a list. We don't worry about duplicates as + these will be sorted out later in + get_best_group_min_max. + @return does the query qualify for indexed AGGFN(DISTINCT) @retval true it does @retval false AGGFN(DISTINCT) must apply distinct in it. @@ -5050,6 +5065,7 @@ is_indexed_agg_distinct(JOIN *join, List<Item_field> *out_args) { Item_sum **sum_item_ptr; bool result= false; + Field_map first_aggdistinct_fields; if (join->table_count != 1 || /* reference more than 1 table */ join->select_distinct || /* or a DISTINCT */ @@ -5062,6 +5078,7 @@ is_indexed_agg_distinct(JOIN *join, List<Item_field> *out_args) for (sum_item_ptr= join->sum_funcs; *sum_item_ptr; sum_item_ptr++) { Item_sum *sum_item= *sum_item_ptr; + Field_map cur_aggdistinct_fields; Item *expr; /* aggregate is not AGGFN(DISTINCT) or more than 1 argument to it */ switch (sum_item->sum_func()) @@ -5091,15 +5108,23 @@ is_indexed_agg_distinct(JOIN *join, List<Item_field> *out_args) if (expr->real_item()->type() != Item::FIELD_ITEM) return false; - /* - If we came to this point the AGGFN(DISTINCT) loose index scan - optimization is applicable - */ + Item_field* item= static_cast<Item_field*>(expr->real_item()); if (out_args) - out_args->push_back((Item_field *) expr->real_item()); + out_args->push_back(item); + + cur_aggdistinct_fields.set_bit(item->field->field_index); result= true; } + /* + If there are multiple aggregate functions, make sure that they all + refer to exactly the same set of columns. + */ + if (first_aggdistinct_fields.is_clear_all()) + first_aggdistinct_fields.merge(cur_aggdistinct_fields); + else if (first_aggdistinct_fields != cur_aggdistinct_fields) + return false; } + return result; } @@ -21169,22 +21194,20 @@ change_to_use_tmp_fields(THD *thd, Item **ref_pointer_array, if (field != NULL) { /* - Replace "@:=<expression>" with "@:=<tmp table column>". Otherwise, - we would re-evaluate <expression>, and if expression were - a subquery, this would access already-unlocked tables. - */ + Replace "@:=<expression>" with "@:=<tmp table column>". Otherwise, we + would re-evaluate <expression>, and if expression were a subquery, this + would access already-unlocked tables. + */ Item_func_set_user_var* suv= - new Item_func_set_user_var((Item_func_set_user_var*) item); + new Item_func_set_user_var(thd, (Item_func_set_user_var*) item); Item_field *new_field= new Item_field(field); - if (!suv || !new_field || suv->fix_fields(thd, (Item**)&suv)) + if (!suv || !new_field) DBUG_RETURN(true); // Fatal error - ((Item *)suv)->name= item->name; /* - We are replacing the argument of Item_func_set_user_var after its - value has been read. The argument's null_value should be set by - now, so we must set it explicitly for the replacement argument - since the null_value may be read without any preceeding call to - val_*(). + We are replacing the argument of Item_func_set_user_var after its value + has been read. The argument's null_value should be set by now, so we + must set it explicitly for the replacement argument since the null_value + may be read without any preceeding call to val_*(). */ new_field->update_null_value(); List<Item> list; @@ -21215,15 +21238,15 @@ change_to_use_tmp_fields(THD *thd, Item **ref_pointer_array, ifield->db_name= iref->db_name; } #ifndef DBUG_OFF - if (!item_field->name) - { - char buff[256]; - String str(buff,sizeof(buff),&my_charset_bin); - str.length(0); - str.extra_allocation(1024); - item->print(&str, QT_ORDINARY); - item_field->name= sql_strmake(str.ptr(),str.length()); - } + if (!item_field->name) + { + char buff[256]; + String str(buff,sizeof(buff),&my_charset_bin); + str.length(0); + str.extra_allocation(1024); + item->print(&str, QT_ORDINARY); + item_field->name= sql_strmake(str.ptr(),str.length()); + } #endif } else |