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Implementation of SUM(DISTINCT), tests cases

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sql/filesort.cc:
  Snippet of filesort() code moved to function reuse_freed_buff() - 
  change buffpek pointers to use buff from freed BUFFPEK
  Used in filesort() and merge_walk().
sql/item_sum.cc:
  Implementation of Item_sum_sum_distinct - SUM(DISTINCT) item, 
  which uses Unique to resolve duplicates
sql/item_sum.h:
  New sum Item added - Item_sum_sum_distinct - for SUM(DISTINCT) function
sql/sql_class.h:
  added walk() and reset() methods to Unique, used in Item_sum_sum_distinct.
sql/sql_sort.h:
  declaration for reuse_freed_buff() to be able to use it in uniques.cc
sql/sql_yacc.yy:
  parser extended to handle MIN(DISTICNT), MAX(DISTINCT), SUM(DISTINCT)
sql/uniques.cc:
  Implementation for Unique::reset(), Unique::walk() as well as for merge_walk() 
  algorithm.
This commit is contained in:
unknown
2003-12-19 19:04:03 +03:00
parent 844d9b766a
commit 58a52a2a84
9 changed files with 834 additions and 35 deletions
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16
sql/sql_class.h
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@ -1207,8 +1207,13 @@ class user_var_entry
DTCollation collation;
};
/* Class for unique (removing of duplicates) */
/*
Unique -- class for unique (removing of duplicates).
Puts all values to the TREE. If the tree becomes too big,
it's dumped to the file. User can request sorted values, or
just iterate through them. In the last case tree merging is performed in
memory simultaneously with iteration, so it should be ~2-3x faster.
*/
class Unique :public Sql_alloc
{
@ -1222,10 +1227,10 @@ class Unique :public Sql_alloc
public:
ulong elements;
Unique(qsort_cmp2 comp_func, void * comp_func_fixed_arg,
Unique(qsort_cmp2 comp_func, void *comp_func_fixed_arg,
uint size_arg, ulong max_in_memory_size_arg);
~Unique();
inline bool unique_add(gptr ptr)
inline bool unique_add(void *ptr)
{
if (tree.elements_in_tree > max_elements && flush())
return 1;
@ -1234,6 +1239,9 @@ public:
bool get(TABLE *table);
void reset();
bool walk(tree_walk_action action, void *walk_action_arg);
friend int unique_write_to_file(gptr key, element_count count, Unique *unique);
friend int unique_write_to_ptrs(gptr key, element_count count, Unique *unique);
};