Fix cost calculation in test_if_cheaper_ordering() to be cost based

The original code was mostly rule based and preferred clustered or
covering indexed independent of cost.

There where a few test changes:
- Some test changed from using filesort to index or table scan. This
  happened when most of the rows had to be sorted and the ORDER BY could
  use covering or a clustered index (innodb_mysql, create_spatial_index).
- Some test changed range to filesort. This where mainly because the range
  was scanning most of the rows or using index scan + row lookup and
  filesort with table scan is cheaper. (order_by).
- Change in join_cache was because sorting 2 rows is faster than retrieving
  10 rows.
- In selectivity_innodb.test one test changed to use a cheaper index.

1 files changed, 3 insertions, 2 deletions

diff --git a/sql/filesort_utils.cc b/sql/filesort_utils.cc
index 4a75817add4..854033cc8d8 100644
--- a/sql/filesort_utils.cc
+++ b/sql/filesort_utils.cc
@@ -28,7 +28,8 @@ const LEX_CSTRING filesort_names[]=
   { STRING_WITH_LEN("priority_queue with addon fields")},
   { STRING_WITH_LEN("priority_queue with row lookup")},
   { STRING_WITH_LEN("merge_sort with addon fields")},
-  { STRING_WITH_LEN("merge_sort with row lookup)")}
+  { STRING_WITH_LEN("merge_sort with row lookup)")},
+  { STRING_WITH_LEN("Error while computing filesort cost")}
 };
 
 /*
@@ -447,7 +448,7 @@ double cost_of_filesort(TABLE *table, ORDER *order_by, ha_rows rows_to_read,
   for (ORDER *ptr= order_by; ptr ; ptr= ptr->next)
   {
     Item_field *field= (Item_field*) (*ptr->item)->real_item();
-    size_t length= get_sort_length(table->in_use, field);
+    size_t length= get_sort_length(thd, field);
     set_if_smaller(length, thd->variables.max_sort_length);
     sort_len+= (uint) length;
   }