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)

mysql-test/r/date_formats.result

@@ -196,16 +196,16 @@ date	format	datetime
 0003-01-02 8:11:2.123456	%Y-%m-%d %H:%i:%S.%#	0003-01-02 08:11:02
 03-01-02 8:11:2.123456	%Y-%m-%d %H:%i:%S.%#	2003-01-02 08:11:02
 2003-01-02 10:11:12 PM	%Y-%m-%d %h:%i:%S %p	2003-01-02 22:11:12
-2003-01-02 01:11:12.12345AM	%Y-%m-%d %h:%i:%S.%f%p	2003-01-02 01:11:12.123450
-2003-01-02 02:11:12.12345AM	%Y-%m-%d %h:%i:%S.%f %p	2003-01-02 02:11:12.123450
-2003-01-02 12:11:12.12345 am	%Y-%m-%d %h:%i:%S.%f%p	2003-01-02 00:11:12.123450
+2003-01-02 01:11:12.12345AM	%Y-%m-%d %h:%i:%S.%f%p	2003-01-02 01:11:12
+2003-01-02 02:11:12.12345AM	%Y-%m-%d %h:%i:%S.%f %p	2003-01-02 02:11:12
+2003-01-02 12:11:12.12345 am	%Y-%m-%d %h:%i:%S.%f%p	2003-01-02 00:11:12
 2003-01-02 11:11:12Pm	%Y-%m-%d %h:%i:%S%p	2003-01-02 23:11:12
 10:20:10	%H:%i:%s	0000-00-00 10:20:10
 10:20:10	%h:%i:%s.%f	0000-00-00 10:20:10
 10:20:10	%T	0000-00-00 10:20:10
 10:20:10AM	%h:%i:%s%p	0000-00-00 10:20:10
 10:20:10AM	%r	0000-00-00 10:20:10
-10:20:10.44AM	%h:%i:%s.%f%p	0000-00-00 10:20:10.440000
+10:20:10.44AM	%h:%i:%s.%f%p	0000-00-00 10:20:10
 15-01-2001 12:59:58	%d-%m-%Y %H:%i:%S	2001-01-15 12:59:58
 15 September 2001	%d %M %Y	2001-09-15 00:00:00
 15 SEPTEMB 2001	%d %M %Y	2001-09-15 00:00:00
@@ -487,7 +487,7 @@ str_to_date(a,b)
 create table t2 select str_to_date(a,b) from t1;
 describe t2;
 Field	Type	Null	Key	Default	Extra
-str_to_date(a,b)	datetime	YES		NULL	
+str_to_date(a,b)	datetime(6)	YES		NULL	
 select str_to_date("2003-01-02 10:11:12.0012", "%Y-%m-%d %H:%i:%S.%f") as f1,
 str_to_date("2003-01-02 10:11:12.0012", "%Y-%m-%d %H:%i:%S") as f2,
 str_to_date("2003-01-02", "%Y-%m-%d") as f3,

mysql-test/r/distinct.result

@@ -805,3 +805,16 @@ a
 2010-10-10
 20101010
 drop table t1;
+create table t1 (f1 varchar(40));
+insert into t1 values ('2010-10-10 00:00:00.0001'),('2010-10-10 00:00:00.0002'),('2010-10-10 00:00:00.0003');
+select time(f1) from t1 ;
+time(f1)
+00:00:00.000100
+00:00:00.000200
+00:00:00.000300
+select distinct time(f1) from t1 ;
+time(f1)
+00:00:00.000100
+00:00:00.000200
+00:00:00.000300
+drop table t1;

mysql-test/r/func_sapdb.result

@@ -195,17 +195,17 @@ time("1997-12-31 23:59:59.000001") as f9;
 describe t1;
 Field	Type	Null	Key	Default	Extra
 f1	date	YES		NULL	
-f2	datetime	YES		NULL	
-f3	time	YES		NULL	
-f4	time	YES		NULL	
-f5	time	YES		NULL	
+f2	datetime(6)	YES		NULL	
+f3	time(6)	YES		NULL	
+f4	time(6)	YES		NULL	
+f5	time(6)	YES		NULL	
 f6	time	YES		NULL	
-f7	datetime	YES		NULL	
+f7	datetime(6)	YES		NULL	
 f8	date	YES		NULL	
-f9	time	YES		NULL	
+f9	time(6)	YES		NULL	
 select * from t1;
 f1	f2	f3	f4	f5	f6	f7	f8	f9
-1997-01-01	1998-01-02 01:01:00	49:01:01	46:58:57	-24:00:00	10:11:12	2001-12-01 01:01:01	1997-12-31	23:59:59
+1997-01-01	1998-01-02 01:01:00.000003	49:01:01.000001	46:58:57.999999	8275:29:36.710655	10:11:12	2001-12-01 01:01:01.000000	1997-12-31	23:59:59.000001
 create table test(t1 datetime, t2 time, t3 time, t4 datetime);
 insert into test values 
 ('2001-01-01 01:01:01', '01:01:01', null, '2001-02-01 01:01:01'),
@@ -230,8 +230,8 @@ SELECT TIMEDIFF(t1, t4) As ttt, TIMEDIFF(t2, t3) As qqq,
 TIMEDIFF(t3, t2) As eee, TIMEDIFF(t2, t4) As rrr from test;
 ttt	qqq	eee	rrr
 -744:00:00	NULL	NULL	NULL
-838:59:59.999999	22:58:58	-22:58:58	NULL
--838:59:59.999999	-22:58:58	22:58:58	NULL
+838:59:59	22:58:58	-22:58:58	NULL
+-838:59:59	-22:58:58	22:58:58	NULL
 NULL	26:02:02	-26:02:02	NULL
 00:00:00	-26:02:02	26:02:02	NULL
 NULL	NULL	NULL	NULL

mysql-test/r/func_time_hires.result

@@ -37,7 +37,7 @@ Table	Create Table
 t1	CREATE TABLE `t1` (
   `sec_to_time(12345)` time DEFAULT NULL,
   `sec_to_time(12345.6789)` time(4) DEFAULT NULL,
-  `sec_to_time(1234567e-2)` time DEFAULT NULL,
+  `sec_to_time(1234567e-2)` time(6) DEFAULT NULL,
   `now()` datetime NOT NULL DEFAULT '0000-00-00 00:00:00',
   `curtime(0)` time NOT NULL DEFAULT '00:00:00',
   `utc_timestamp(1)` datetime(1) NOT NULL DEFAULT '0000-00-00 00:00:00.0',
@@ -52,7 +52,7 @@ t1	CREATE TABLE `t1` (
 select * from t1;
 sec_to_time(12345)	03:25:45
 sec_to_time(12345.6789)	03:25:45.6789
-sec_to_time(1234567e-2)	03:25:45
+sec_to_time(1234567e-2)	03:25:45.670000
 now()	2011-01-01 01:01:01
 curtime(0)	01:01:01
 utc_timestamp(1)	2010-12-31 22:01:01.1

mysql-test/t/distinct.test

@@ -624,3 +624,12 @@ select * from t1 where a = DATE('2010-10-10');
 select distinct a from t1 where a = DATE('2010-10-10');
 drop table t1;
 
+#
+# lp:731124 Loss of precision on DISTINCT
+#
+create table t1 (f1 varchar(40));
+insert into t1 values ('2010-10-10 00:00:00.0001'),('2010-10-10 00:00:00.0002'),('2010-10-10 00:00:00.0003');
+select time(f1) from t1 ;
+select distinct time(f1) from t1 ;
+drop table t1;
+

sql/field.h

@@ -1501,12 +1501,13 @@ new_Field_timestamp(uchar *ptr, uchar *null_ptr, uchar null_bit,
                     enum Field::utype unireg_check, const char *field_name,
                     TABLE_SHARE *share, uint dec, CHARSET_INFO *cs)
 {
-  if (dec==0 || dec == NOT_FIXED_DEC)
+  if (dec==0)
     return new Field_timestamp(ptr, MAX_DATETIME_WIDTH, null_ptr, null_bit,
                                 unireg_check, field_name, share, cs);
-  else
-    return new Field_timestamp_hires(ptr, null_ptr, null_bit, unireg_check,
-                                     field_name, share, dec, cs);
+  if (dec == NOT_FIXED_DEC)
+    dec= MAX_DATETIME_PRECISION;
+  return new Field_timestamp_hires(ptr, null_ptr, null_bit, unireg_check,
+                                   field_name, share, dec, cs);
 }
 
 static inline Field_time *
@@ -1514,12 +1515,13 @@ new_Field_time(uchar *ptr, uchar *null_ptr, uchar null_bit,
                enum Field::utype unireg_check, const char *field_name,
                uint dec, CHARSET_INFO *cs)
 {
-  if (dec == 0 || dec == NOT_FIXED_DEC)
+  if (dec == 0)
     return new Field_time(ptr, MIN_TIME_WIDTH, null_ptr, null_bit,
                           unireg_check, field_name, cs);
-  else
-    return new Field_time_hires(ptr, null_ptr, null_bit,
-                                    unireg_check, field_name, dec, cs);
+  if (dec == NOT_FIXED_DEC)
+    dec= MAX_DATETIME_PRECISION;
+  return new Field_time_hires(ptr, null_ptr, null_bit,
+                                  unireg_check, field_name, dec, cs);
 }
 
 static inline Field_datetime *
@@ -1527,12 +1529,13 @@ new_Field_datetime(uchar *ptr, uchar *null_ptr, uchar null_bit,
                    enum Field::utype unireg_check,
                    const char *field_name, uint dec, CHARSET_INFO *cs)
 {
-  if (dec == 0 || dec == NOT_FIXED_DEC)
+  if (dec == 0)
     return new Field_datetime(ptr, MAX_DATETIME_WIDTH, null_ptr, null_bit,
                               unireg_check, field_name, cs);
-  else
-    return new Field_datetime_hires(ptr, null_ptr, null_bit,
-                                    unireg_check, field_name, dec, cs);
+  if (dec == NOT_FIXED_DEC)
+    dec= MAX_DATETIME_PRECISION;
+  return new Field_datetime_hires(ptr, null_ptr, null_bit,
+                                  unireg_check, field_name, dec, cs);
 }
 
 class Field_string :public Field_longstr {

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; }
 };
 

sql/item_cmpfunc.cc

@@ -2920,6 +2920,13 @@ void Item_func_coalesce::fix_length_and_dec()
 {
   cached_field_type= agg_field_type(args, arg_count);
   agg_result_type(&hybrid_type, args, arg_count);
+  Item_result cmp_type;
+  agg_cmp_type(&cmp_type, args, arg_count);
+  if (cmp_type == TIME_RESULT)
+  {
+    count_real_length();
+    return;
+  }
   switch (hybrid_type) {
   case STRING_RESULT:
     count_only_length();

sql/item_create.cc

@@ -5091,7 +5091,7 @@ create_func_cast(THD *thd, Item *a, Cast_target cast_type,
       }
     }
     else
-      len= NOT_FIXED_DEC;
+      len= 0;
 
     if (cast_type == ITEM_CAST_TIME)
       res= new (thd->mem_root) Item_time_typecast(a, len);

sql/item_timefunc.cc

@@ -2379,7 +2379,7 @@ void Item_func_add_time::fix_length_and_dec()
 {
   enum_field_types arg0_field_type;
   max_length= MAX_DATETIME_WIDTH;
-  decimals= NOT_FIXED_DEC;
+  decimals= max(args[0]->decimals, args[1]->decimals);
   maybe_null= 1;
 
   /*

sql/item_timefunc.h

@@ -765,7 +765,7 @@ public:
   const char *func_name() const { return "timediff"; }
   void fix_length_and_dec()
   {
-    decimals= NOT_FIXED_DEC;
+    decimals= max(args[0]->decimals, args[1]->decimals);
     Item_timefunc::fix_length_and_dec();
     maybe_null= 1;
   }