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fixes/optimizations for count(distinct)

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more extensive testing of count(distinct)


sql/item_sum.cc:
  fixes/optimizations for count(distinct)
This commit is contained in:
unknown 2001-05-12 17:52:54 -06:00
commit 6498429624
3 changed files with 130 additions and 9 deletions
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25
sql/item_sum.cc
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@ -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;
}
@ -919,11 +923,14 @@ bool Item_sum_count_distinct::setup(THD *thd)
void Item_sum_count_distinct::reset()
{
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);
else
{
table->file->extra(HA_EXTRA_NO_CACHE);
table->file->delete_all_rows();
table->file->extra(HA_EXTRA_WRITE_CACHE);
}
(void) add();
}