Commit b2977103 authored by sasha@mysql.sashanet.com's avatar sasha@mysql.sashanet.com
Browse files

fixes/optimizations for count(distinct) 

more extensive testing of count(distinct)
parent c706bf40

mysql-test/r/count_distinct2.result

0 → 100644
+72 −0
Original line number Diff line number Diff line 
n1

1

2

NULL

count(distinct n1)

2

n2

11

12

13

NULL

count(distinct n2)

3

s

one

two

NULL

count(distinct s)

2

vs

eleven

twevle

thirteen

NULL

count(distinct vs)

3

t

eleven

twelve

foo

bar

NULL

count(distinct t)

4

n1	n2

1	11

2	11

2	12

2	13

NULL	13

2	NULL

count(distinct n1,n2)

4

n1	s

1	one

2	two

NULL	two

2	NULL

count(distinct n1,s)

2

s	n1	vs

one	1	eleven

two	2	eleven

two	2	twevle

two	2	thirteen

two	NULL	thirteen

NULL	2	thirteen

two	2	NULL

count(distinct s,n1,vs)

4

s	t

one	eleven

two	eleven

two	twelve

two	foo

two	bar

NULL	bar

two	NULL

count(distinct s,t)

5

count(distinct n1)	count(distinct n2)

2	3

mysql-test/t/count_distinct2.test

0 → 100644
+42 −0
Original line number Diff line number Diff line 
create table t1(n1 int, n2 int, s char(20), vs varchar(20), t text);

insert into t1 values (1,11, 'one','eleven', 'eleven'),

 (1,11, 'one','eleven', 'eleven'),

 (2,11, 'two','eleven', 'eleven'),

 (2,12, 'two','twevle', 'twelve'),

 (2,13, 'two','thirteen', 'foo'),

 (2,13, 'two','thirteen', 'foo'),

 (2,13, 'two','thirteen', 'bar'),

 (NULL,13, 'two','thirteen', 'bar'),

 (2,NULL, 'two','thirteen', 'bar'),

 (2,13, NULL,'thirteen', 'bar'),

 (2,13, 'two',NULL, 'bar'),

 (2,13, 'two','thirteen', NULL);



select distinct n1 from t1;

select count(distinct n1) from t1;



select distinct n2 from t1;

select count(distinct n2) from t1;



select distinct s from t1;

select count(distinct s) from t1;



select distinct vs from t1;

select count(distinct vs) from t1;



select distinct t from t1;

select count(distinct t) from t1;



select distinct n1,n2 from t1;

select count(distinct n1,n2) from t1;



select distinct n1,s from t1;

select count(distinct n1,s) from t1;



select distinct s,n1,vs from t1;

select count(distinct s,n1,vs) from t1;



select distinct s,t from t1;

select count(distinct s,t) from t1;



select count(distinct n1), count(distinct n2) from t1;

sql/item_sum.cc

+16 −9
Original line number Diff line number Diff line
@@ -810,12 +810,13 @@ int composite_key_cmp(void* arg, byte* key1, byte* key2) 
  for(; field < field_end; ++field)

    {

      int res;

      int len = (*field)->field_length;

      Field* f = *field;

      int len = f->field_length;

      switch((*field)->type())

	{

	case FIELD_TYPE_STRING:

	case FIELD_TYPE_VAR_STRING:

	  res = my_sortcmp(key1, key2, len);

	  res = f->key_cmp(key1, key2);

	  break;

	default:

	  res = memcmp(key1, key2, len);
@@ -879,20 +880,22 @@ bool Item_sum_count_distinct::setup(THD *thd) 
	// to use a simpler key compare method that can take advantage

	// of not having to worry about other fields

	{

	  switch(table->field[0]->type())

	  Field* field = table->field[0];

	  switch(field->type())

	    {

	      // if we have a string, we must take care of charsets

	      // and case sensitivity

	    case FIELD_TYPE_STRING:

	    case FIELD_TYPE_VAR_STRING:

	      compare_key = (qsort_cmp2)simple_str_key_cmp;

	      compare_key = (qsort_cmp2)(field->binary() ? simple_raw_key_cmp:

					 simple_str_key_cmp);

	      break;

	    default: // since at this point we cannot have blobs

	      // anything else can be compared with memcmp

	      compare_key = (qsort_cmp2)simple_raw_key_cmp;

	      break;

	    }

	  cmp_arg = (void*)(key_len = table->field[0]->field_length);

	  cmp_arg = (void*)(key_len = field->field_length);

	  rec_offset = 1;

	}

      else // too bad, cannot cheat - there is more than one field
@@ -908,7 +911,8 @@ bool Item_sum_count_distinct::setup(THD *thd) 
	  rec_offset = table->reclength - key_len;

	}



      init_tree(&tree, 0, key_len, compare_key, 0, 0);

      init_tree(&tree, min(max_heap_table_size, sortbuff_size/16),

		key_len, compare_key, 0, 0);

      tree.cmp_arg = cmp_arg;

      use_tree = 1;

    }
@@ -918,12 +922,15 @@ bool Item_sum_count_distinct::setup(THD *thd) 




void Item_sum_count_distinct::reset()

{

  if(use_tree)

    delete_tree(&tree);

  else

    {

      table->file->extra(HA_EXTRA_NO_CACHE);

      table->file->delete_all_rows();

      table->file->extra(HA_EXTRA_WRITE_CACHE);

  if(use_tree)

    delete_tree(&tree);

    }

  (void) add();

}