Fixed bug#15560: GROUP_CONCAT wasn't ready for WITH ROLLUP queries

The GROUP_CONCAT uses its own temporary table. When ROLLUP is present
it creates the second copy of Item_func_group_concat. This copy receives the
same list of arguments that original group_concat does. When the copy is
set up the result_fields of functions from the argument list are reset to the
temporary table of this copy.
As a result of this action data from functions flow directly to the ROLLUP copy
and the original group_concat functions shows wrong result.
Since queries with COUNT(DISTINCT ...) use temporary tables to store
the results the COUNT function they are also affected by this bug.

The idea of the fix is to copy content of the result_field for the function
under GROUP_CONCAT/COUNT from  the first temporary table to the second one,
rather than setting result_field to point to the second temporary table.
To achieve this goal force_copy_fields flag is added to Item_func_group_concat
and Item_sum_count_distinct classes. This flag is initialized to 0 and set to 1
into the make_unique() member function of both classes.
To the TMP_TABLE_PARAM structure is modified to include the similar flag as
well.
The create_tmp_table() function passes that flag to create_tmp_field().
When the flag is set the create_tmp_field() function will set result_field
as a source field and will not reset that result field to newly created 
field for Item_func_result_field and its descendants. Due to this there
will be created copy func to copy data from old result_field to newly 
created field.

mysql-test/r/func_gconcat.result

@@ -589,3 +589,18 @@ GROUP_CONCAT(a ORDER BY a)
 ,x
 ,z
 DROP TABLE t1;
+create table t1(f1 int);
+insert into t1 values(1),(2),(3);
+select f1, group_concat(f1+1) from t1 group by f1 with rollup;
+f1	group_concat(f1+1)
+1	2
+2	3
+3	4
+NULL	2,3,4
+select count(distinct (f1+1)) from t1 group by f1 with rollup;
+count(distinct (f1+1))
+1
+1
+1
+3
+drop table t1;

mysql-test/t/func_gconcat.test

@@ -382,4 +382,12 @@ SELECT GROUP_CONCAT(a ORDER BY a) FROM t1 GROUP BY id;
 
 DROP TABLE t1;
 
+#
+# Bug #15560: GROUP_CONCAT wasn't ready for WITH ROLLUP queries
+#
+create table t1(f1 int);
+insert into t1 values(1),(2),(3);
+select f1, group_concat(f1+1) from t1 group by f1 with rollup;
+select count(distinct (f1+1)) from t1 group by f1 with rollup;
+drop table t1;
 # End of 4.1 tests

sql/item_sum.cc

@@ -1185,6 +1185,7 @@ void Item_sum_count_distinct::make_unique()
   original= 0;
   use_tree= 0; // to prevent delete_tree call on uninitialized tree
   tree= &tree_base;
+  force_copy_fields= 1;
 }
 
 
@@ -1219,6 +1220,7 @@ bool Item_sum_count_distinct::setup(THD *thd)
     free_tmp_table(thd, table);
     tmp_table_param->cleanup();
   }
+  tmp_table_param->force_copy_fields= force_copy_fields;
   if (!(table= create_tmp_table(thd, tmp_table_param, list, (ORDER*) 0, 1,
 				0,
 				select_lex->options | thd->options,
@@ -1724,6 +1726,7 @@ Item_func_group_concat::Item_func_group_concat(bool is_distinct,
 					       String *is_separator)
   :Item_sum(), tmp_table_param(0), max_elements_in_tree(0), warning(0),
    key_length(0), tree_mode(0), distinct(is_distinct), warning_for_row(0),
+   force_copy_fields(0),
    separator(is_separator), tree(&tree_base), table(0),
    order(0), tables_list(0),
    arg_count_order(0), arg_count_field(0),
@@ -1785,6 +1788,7 @@ Item_func_group_concat::Item_func_group_concat(THD *thd,
   tree_mode(item->tree_mode),
   distinct(item->distinct),
   warning_for_row(item->warning_for_row),
+  force_copy_fields(item->force_copy_fields),
   separator(item->separator),
   tree(item->tree),
   table(item->table),
@@ -2004,6 +2008,7 @@ bool Item_func_group_concat::setup(THD *thd)
     free_tmp_table(thd, table);
     tmp_table_param->cleanup();
   }
+  tmp_table_param->force_copy_fields= force_copy_fields;
   /*
     We have to create a temporary table to get descriptions of fields 
     (types, sizes and so on).
@@ -2079,6 +2084,7 @@ void Item_func_group_concat::make_unique()
   original= 0;
   tree_mode= 0; // to prevent delete_tree call on uninitialized tree
   tree= &tree_base;
+  force_copy_fields= 1;
 }
 
 

sql/item_sum.h

@@ -185,6 +185,7 @@ class Item_sum_count_distinct :public Item_sum_int
   TMP_TABLE_PARAM *tmp_table_param;
   TREE tree_base;
   TREE *tree;
+  bool force_copy_fields;
   /*
     Following is 0 normal object and pointer to original one for copy 
     (to correctly free resources)
@@ -226,15 +227,16 @@ class Item_sum_count_distinct :public Item_sum_int
   public:
   Item_sum_count_distinct(List<Item> &list)
     :Item_sum_int(list), table(0), used_table_cache(~(table_map) 0),
-     tmp_table_param(0), tree(&tree_base), original(0), use_tree(0),
+     tmp_table_param(0), tree(&tree_base), force_copy_fields(0), original(0),
-     always_null(0)
+     use_tree(0), always_null(0)
   { quick_group= 0; }
   Item_sum_count_distinct(THD *thd, Item_sum_count_distinct *item)
     :Item_sum_int(thd, item), table(item->table),
      used_table_cache(item->used_table_cache),
      field_lengths(item->field_lengths),
      tmp_table_param(item->tmp_table_param),
-     tree(item->tree), original(item), key_length(item->key_length),
+     tree(item->tree), force_copy_fields(item->force_copy_fields),
+     original(item), key_length(item->key_length),
      max_elements_in_tree(item->max_elements_in_tree),
      rec_offset(item->rec_offset), use_tree(item->use_tree),
      always_null(item->always_null)
@@ -685,6 +687,7 @@ class Item_func_group_concat : public Item_sum
   bool distinct;
   bool warning_for_row;
   bool always_null;
+  bool force_copy_fields;
 
   friend int group_concat_key_cmp_with_distinct(void* arg, byte* key1,
 					      byte* key2);

sql/mysql_priv.h

@@ -537,8 +537,9 @@ int mysql_union(THD *thd, LEX *lex, select_result *result,
 		SELECT_LEX_UNIT *unit);
 int mysql_handle_derived(LEX *lex);
 Field *create_tmp_field(THD *thd, TABLE *table,Item *item, Item::Type type,
-			Item ***copy_func, Field **from_field,
+                        Item ***copy_func, Field **from_field,
-			bool group, bool modify_item, uint convert_blob_length);
+                        bool group, bool modify_item, uint convert_blob_length,
+                        bool make_copy_field);
 int mysql_prepare_table(THD *thd, HA_CREATE_INFO *create_info,
 		       List<create_field> &fields,
 		       List<Key> &keys, uint &db_options, 

sql/sql_class.h

@@ -1334,10 +1334,11 @@ public:
   bool  using_indirect_summary_function;
   /* If >0 convert all blob fields to varchar(convert_blob_length) */
   uint  convert_blob_length; 
-
+  bool force_copy_fields;
   TMP_TABLE_PARAM()
     :copy_field(0), group_parts(0),
-    group_length(0), group_null_parts(0), convert_blob_length(0)
+    group_length(0), group_null_parts(0), convert_blob_length(0),
+    force_copy_fields(0)
   {}
   ~TMP_TABLE_PARAM()
   {

sql/sql_select.cc

@@ -4984,7 +4984,8 @@ static Field* create_tmp_field_from_item(THD *thd, Item *item, TABLE *table,
 
 Field *create_tmp_field(THD *thd, TABLE *table,Item *item, Item::Type type,
                         Item ***copy_func, Field **from_field,
-                        bool group, bool modify_item, uint convert_blob_length)
+                        bool group, bool modify_item, uint convert_blob_length,
+                        bool make_copy_field)
 {
   switch (type) {
   case Item::SUM_FUNC_ITEM:
@@ -5071,7 +5072,13 @@ Field *create_tmp_field(THD *thd, TABLE *table,Item *item, Item::Type type,
   case Item::REF_ITEM:
   case Item::NULL_ITEM:
   case Item::VARBIN_ITEM:
-    return create_tmp_field_from_item(thd, item, table, copy_func, modify_item,
+    if (make_copy_field)
+    {
+      DBUG_ASSERT(((Item_result_field*)item)->result_field);
+      *from_field= ((Item_result_field*)item)->result_field;
+    }
+    return create_tmp_field_from_item(thd, item, table, (make_copy_field ? 0 :
+                                      copy_func), modify_item,
                                       convert_blob_length);
   case Item::TYPE_HOLDER:
     return ((Item_type_holder *)item)->make_field_by_type(table);
@@ -5110,7 +5117,7 @@ create_tmp_table(THD *thd,TMP_TABLE_PARAM *param,List<Item> &fields,
   Item **copy_func;
   MI_COLUMNDEF *recinfo;
   uint temp_pool_slot=MY_BIT_NONE;
-
+  bool force_copy_fields= param->force_copy_fields;
   DBUG_ENTER("create_tmp_table");
   DBUG_PRINT("enter",("distinct: %d  save_sum_fields: %d  rows_limit: %lu  group: %d",
 		      (int) distinct, (int) save_sum_fields,
@@ -5241,7 +5248,7 @@ create_tmp_table(THD *thd,TMP_TABLE_PARAM *param,List<Item> &fields,
 	  Field *new_field=
             create_tmp_field(thd, table, arg, arg->type(), &copy_func,
                              tmp_from_field, group != 0,not_all_columns,
-                             param->convert_blob_length);
+                             param->convert_blob_length, 0);
 	  if (!new_field)
 	    goto err;					// Should be OOM
 	  tmp_from_field++;
@@ -5279,8 +5286,10 @@ create_tmp_table(THD *thd,TMP_TABLE_PARAM *param,List<Item> &fields,
       */
       Field *new_field= create_tmp_field(thd, table, item, type, &copy_func,
                                          tmp_from_field, group != 0,
-                                         not_all_columns || group !=0,
+                                         !force_copy_fields &&
-                                         param->convert_blob_length);
+                                           (not_all_columns || group !=0),
+                                         param->convert_blob_length,
+                                         force_copy_fields);
       if (!new_field)
       {
 	if (thd->is_fatal_error)

sql/sql_table.cc

@@ -1562,7 +1562,7 @@ TABLE *create_table_from_items(THD *thd, HA_CREATE_INFO *create_info,
       field=item->tmp_table_field(&tmp_table);
     else
       field=create_tmp_field(thd, &tmp_table, item, item->type(),
-				  (Item ***) 0, &tmp_field, 0, 0, 0);
+				  (Item ***) 0, &tmp_field, 0, 0, 0, 0);
     if (!field ||
 	!(cr_field=new create_field(field,(item->type() == Item::FIELD_ITEM ?
 					   ((Item_field *)item)->field :