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use tree for count(distinct) when possible

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include/my_tree.h:
  fixed typo in comment
mysys/tree.c:
  fixed typo in comment
sql/item_sum.h:
  use tree for count distinct when possible
This commit is contained in:
unknown 2001-05-11 15:07:34 -06:00
commit 1d56c0324e
4 changed files with 117 additions and 5 deletions
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13
sql/item_sum.h
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@ -21,6 +21,8 @@
#pragma interface /* gcc class implementation */
#endif
#include <my_tree.h>
class Item_sum :public Item_result_field
{
public:
@ -145,11 +147,20 @@ class Item_sum_count_distinct :public Item_sum_int
table_map used_table_cache;
bool fix_fields(THD *thd,TABLE_LIST *tables);
TMP_TABLE_PARAM *tmp_table_param;
TREE tree;
bool use_tree; // If there are no blobs, we can use a tree, which
// is faster than heap table. In that case, we still use the table
// to help get things set up, but we insert nothing in it
int rec_offset; // the first few bytes of record ( at least one)
// are just markers for deleted and NULLs. We want to skip them since
// they will just bloat the tree without providing any valuable info
friend int composite_key_cmp(void* arg, byte* key1, byte* key2);
public:
Item_sum_count_distinct(List<Item> &list)
:Item_sum_int(list),table(0),used_table_cache(~(table_map) 0),
tmp_table_param(0)
tmp_table_param(0),use_tree(0)
{ quick_group=0; }
~Item_sum_count_distinct();
table_map used_tables() const { return used_table_cache; }