lp:731124 Loss of precision on DISTINCT

many changes:
* NOT_FIXED_DEC now create hires fields, not old ones.
  As a result, temp tables preserve microseconds (on DISTINCT, GROUP BY)
* I_S tables force decimals=0 on temporal types (backward compatibility)
* Item_func_coalesce calculates decimals for temporal types
* no precision for TIME/DATETIME in CAST means 0, not NOT_FIXED_DEC
* addtime/timediff calculate decimals from arguments (not NOT_FIXED_DEC)

sql/field.h:
  NOT_FIXED_DEC now create hires fields, not old ones
sql/item.h:
  force decimals=0 for I_S tables
sql/item_cmpfunc.cc:
  Item_func_coalesce calculates decimals for temporal types
sql/item_create.cc:
  no precision for TIME/DATETIME in CAST means 0, not NOT_FIXED_DEC
sql/item_timefunc.cc:
  addtime calculates decimals from arguments (not NOT_FIXED_DEC)
sql/item_timefunc.h:
  timediff calculates decimals from arguments (not NOT_FIXED_DEC)

1 files changed, 1 insertions, 1 deletions

diff --git a/sql/item.h b/sql/item.h
index 0be8312750d..af0f3d1c024 100644
--- a/sql/item.h
+++ b/sql/item.h
@@ -2075,7 +2075,7 @@ public:
                         enum_field_types field_type_arg)
     :Item_partition_func_safe_string(name_arg, length_arg, &my_charset_bin),
      date_time_field_type(field_type_arg)
-  { }
+  { decimals= 0; }
   enum_field_types field_type() const { return date_time_field_type; }
 };