Fix for bug #4131 "TIMESTAMP columns missing minutes and seconds when

using GROUP BY"
Now we are setting Field_timestamp::field_length to 19 in open_table()
if we are in new mode (and we are restoring it back when we are coming
back to normal mode). This also should solve potential problems with
some of LOAD DATA INFILE and SELECT * INTO in this mode.


mysql-test/r/type_timestamp.result:
  Added test for bug #4131 'TIMESTAMP columns missing minutes and seconds
  when using GROUP BY' and other --new mode related behavior.
mysql-test/t/type_timestamp.test:
  Added test for bug #4131 'TIMESTAMP columns missing minutes and seconds
  when using GROUP BY' and other --new mode related behavior.
sql/field.cc:
  Added Field_timestamp::orig_field_length member for saving original
  field_length value, because this member can be modified if new_mode is
  in effect.
  Lot of Field_timestamp code simplified and Field_timestamp::make_field()
  is no longer needed because we are setting field_length to 19 if we are
  in --new mode now.
sql/field.h:
  Added Field_timestamp::orig_field_length member for saving original
  field_length value, because this member can be modified if new_mode
  is in effect. 
  Field_timestamp::make_field() is no longer needed because we are setting
  field_length to 19 if we are in --new mode now.
sql/sql_base.cc:
  If --new mode is in effect all TIMESTAMP fields should pretend that they
  have length of 19. We are achieving this by setting 
  Field_timestamp::field_length to 19 (or original value) in open_table().
  We are using TABLE::timestamp_mode variable for avoiding of unnecessary
  looping over all fields of the table and setting field_length if table
  was used with same new_mode value before.
  
  Note: We do not introduce general framework for setting up Field objects
  for usage with current THD here because this fix is only needed in 4.0
  and Monty said that we will also remove looping over all fields when
  updating table_name member at some point. This more general framework
  will also complicate nice optimization with avoiding of unneeded looping.
sql/sql_parse.cc:
  Now when we are creating TIMESTAMP(19) fields by default in --new mode,
  otherwise we will have unaligned behavior between ALTER and CREATE.
sql/table.h:
  Added TABLE::timestamp_mode field for saving information whenever we set 
  field_length members of table's TIMESTAMP fields to 19 (to honor 
  new_mode) or they have original values.

mysql-test/r/type_timestamp.result

@@ -122,40 +122,41 @@ t2	t4	t6	t8	t10	t12	t14
 0000-00-00 00:00:00	0000-00-00 00:00:00	0000-00-00 00:00:00	0000-00-00 00:00:00	0000-00-00 00:00:00	0000-00-00 00:00:00	0000-00-00 00:00:00
 1997-12-31 23:47:59	1997-12-31 23:47:59	1997-12-31 23:47:59	1997-12-31 23:47:59	1997-12-31 23:47:59	1997-12-31 23:47:59	1997-12-31 23:47:59
 drop table t1;
+set new=0;
 create table t1 (t1 timestamp default '2003-01-01 00:00:00', 
 t2 timestamp default '2003-01-01 00:00:00');
 set TIMESTAMP=1000000000;
 insert into t1 values();
 select * from t1;
 t1	t2
-2001-09-09 04:46:40	2003-01-01 00:00:00
+20010909044640	20030101000000
 show create table t1;
 Table	Create Table
 t1	CREATE TABLE `t1` (
   `t1` timestamp(14) NOT NULL,
-  `t2` timestamp(14) NOT NULL default '2003-01-01 00:00:00'
+  `t2` timestamp(14) NOT NULL default '20030101000000'
 ) TYPE=MyISAM
 show columns from t1;
 Field	Type	Null	Key	Default	Extra
 t1	timestamp(14)	YES		NULL	
-t2	timestamp(14)	YES		2003-01-01 00:00:00	
+t2	timestamp(14)	YES		20030101000000	
 show columns from t1 like 't2';
 Field	Type	Null	Key	Default	Extra
-t2	timestamp(14)	YES		2003-01-01 00:00:00	
+t2	timestamp(14)	YES		20030101000000	
 create table t2 (select * from t1);
 show create table t2;
 Table	Create Table
 t2	CREATE TABLE `t2` (
   `t1` timestamp(14) NOT NULL,
-  `t2` timestamp(14) NOT NULL default '2003-01-01 00:00:00'
+  `t2` timestamp(14) NOT NULL default '20030101000000'
 ) TYPE=MyISAM
 alter table t1 add column t0 timestamp first;
 show create table t1;
 Table	Create Table
 t1	CREATE TABLE `t1` (
   `t0` timestamp(14) NOT NULL,
-  `t1` timestamp(14) NOT NULL default '2003-01-01 00:00:00',
-  `t2` timestamp(14) NOT NULL default '2003-01-01 00:00:00'
+  `t1` timestamp(14) NOT NULL default '20030101000000',
+  `t2` timestamp(14) NOT NULL default '20030101000000'
 ) TYPE=MyISAM
 drop table t1,t2;
 create table t1 (ts1 timestamp, ts2 timestamp);
@@ -164,8 +165,8 @@ insert into t1 values ();
 insert into t1 values (DEFAULT, DEFAULT);
 select * from t1;
 ts1	ts2
-2001-09-09 04:46:40	0000-00-00 00:00:00
-2001-09-09 04:46:40	0000-00-00 00:00:00
+20010909044640	00000000000000
+20010909044640	00000000000000
 drop table t1;
 create table t1 (ts timestamp(19));
 show create table t1;
@@ -179,3 +180,44 @@ select * from t1;
 ts
 2001-09-09 04:46:40
 drop table t1;
+set new=1;
+create table t1 (a char(2), t timestamp);
+insert into t1 values ('a', '2004-01-01 00:00:00'), ('a', '2004-01-01 01:00:00'),
+('b', '2004-02-01 00:00:00');
+select max(t) from t1 group by a;
+max(t)
+2004-01-01 01:00:00
+2004-02-01 00:00:00
+drop table t1;
+create table t1 (ts1 timestamp);
+show create table t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `ts1` timestamp(19) NOT NULL
+) TYPE=MyISAM
+alter table t1 add ts2 timestamp;
+set new=0;
+show create table t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `ts1` timestamp(19) NOT NULL,
+  `ts2` timestamp(19) NOT NULL default '0000-00-00 00:00:00'
+) TYPE=MyISAM
+drop table t1;
+create table t1 (ts1 timestamp);
+insert into t1 values ('2004-01-01 00:00:00'), ('2004-01-01 01:00:00');
+select * from t1;
+ts1
+20040101000000
+20040101010000
+set new=1;
+select * from t1;
+ts1
+2004-01-01 00:00:00
+2004-01-01 01:00:00
+set new=0;
+select * from t1;
+ts1
+20040101000000
+20040101010000
+drop table t1;

mysql-test/t/type_timestamp.test

@@ -71,6 +71,7 @@ select * from t1;
 set new=1;
 select * from t1;
 drop table t1;
+set new=0;
 
 #
 # Bug #1885, bug #2539. 
@@ -116,3 +117,34 @@ set TIMESTAMP=1000000000;
 insert into t1 values ();
 select * from t1;
 drop table t1;
+
+#
+# Test for bug #4131, TIMESTAMP columns missing minutes and seconds when
+# using GROUP BY in @@new=1 mode.
+#
+set new=1;
+create table t1 (a char(2), t timestamp);
+insert into t1 values ('a', '2004-01-01 00:00:00'), ('a', '2004-01-01 01:00:00'),
+                      ('b', '2004-02-01 00:00:00');
+select max(t) from t1 group by a;
+drop table t1;
+
+#
+# More --new mode tests
+# Both columns created before and during alter should have same length.
+#
+create table t1 (ts1 timestamp);
+show create table t1;
+alter table t1 add ts2 timestamp;
+set new=0;
+show create table t1;
+drop table t1;
+# Selecting from table in --new mode should not affect further selects.
+create table t1 (ts1 timestamp);
+insert into t1 values ('2004-01-01 00:00:00'), ('2004-01-01 01:00:00');
+select * from t1;
+set new=1;
+select * from t1;
+set new=0;
+select * from t1;
+drop table t1;

sql/field.cc

@@ -2467,8 +2467,7 @@ void Field_double::sql_type(String &res) const
 
 enum Item_result Field_timestamp::result_type() const
 {
- return (!current_thd->variables.new_mode &&
-	 (field_length == 8 || field_length == 14) ? INT_RESULT :
+ return ((field_length == 8 || field_length == 14) ? INT_RESULT :
 	 STRING_RESULT);
 }
 
@@ -2480,6 +2479,9 @@ Field_timestamp::Field_timestamp(char *ptr_arg, uint32 len_arg,
     :Field_num(ptr_arg, len_arg, (uchar*) 0,0,
 	       unireg_check_arg, field_name_arg, table_arg,
 	       0, 1, 1)
+#if MYSQL_VERSION_ID < 40100
+    , orig_field_length(len_arg)
+#endif
 {
   if (table && !table->timestamp_field)
   {
@@ -2697,7 +2699,7 @@ String *Field_timestamp::val_str(String *val_buffer,
   time_t time_arg;
   struct tm *l_time;
   struct tm tm_tmp;
-  my_bool new_format= (current_thd->variables.new_mode) || field_length == 19,
+  my_bool new_format= field_length == 19,
           full_year=(field_length == 8 || field_length == 14 || new_format);
   int real_field_length= new_format ? 19 : field_length;
 
@@ -2859,22 +2861,6 @@ void Field_timestamp::set_time()
     longstore(ptr,tmp);
 }
 
-/*
- This is an exact copy of Field_num except that 'length' is depending
- on --new mode
-*/
-
-void Field_timestamp::make_field(Send_field *field)
-{
-  field->table_name=table_name;
-  field->col_name=field_name;
-  /* If --new, then we are using "YYYY-MM-DD HH:MM:SS" format */
-  field->length= current_thd->variables.new_mode ? 19 : field_length;
-  field->type=type();
-  field->flags=table->maybe_null ? (flags & ~NOT_NULL_FLAG) : flags;
-  field->decimals=dec;
-}
-
 
 /****************************************************************************
 ** time type

sql/field.h

@@ -546,6 +546,13 @@ public:
 
 
 class Field_timestamp :public Field_num {
+#if MYSQL_VERSION_ID < 40100
+  /*
+    We save the original field length here because field_length is
+    changed to a mock value in case when the 'new_mode' is in effect.
+  */
+  uint32 orig_field_length;
+#endif
 public:
   Field_timestamp(char *ptr_arg, uint32 len_arg,
 		  enum utype unireg_check_arg, const char *field_name_arg,
@@ -587,7 +594,11 @@ public:
   void fill_and_store(char *from,uint len);
   bool get_date(TIME *ltime,bool fuzzydate);
   bool get_time(TIME *ltime);
-  void make_field(Send_field *field);
+
+#if MYSQL_VERSION_ID < 40100
+  friend TABLE *open_table(THD *thd,const char *db,const char *table_name,
+                           const char *alias,bool *refresh);
+#endif
 };
 
 

sql/sql_base.cc

@@ -941,6 +941,31 @@ TABLE *open_table(THD *thd,const char *db,const char *table_name,
     for (uint i=0 ; i < table->fields ; i++)
       table->field[i]->table_name=table->table_name;
   }
+#if MYSQL_VERSION_ID < 40100
+  /*
+    If per-connection "new" variable (represented by variables.new_mode)
+    is set then we should pretend that the length of TIMESTAMP field is 19.
+    The cheapest (from perfomance viewpoint) way to achieve that is to set
+    field_length of all Field_timestamp objects in a table after opening
+    it (to 19 if new_mode is true or to original field length otherwise).
+    We save value of new_mode variable in TABLE::timestamp_mode to
+    not perform this setup if new_mode value is the same between sequential
+    table opens.
+  */
+  my_bool new_mode= thd->variables.new_mode;
+  if (table->timestamp_mode != new_mode)
+  {
+    for (uint i=0 ; i < table->fields ; i++)
+    {
+      Field *field= table->field[i];
+
+      if (field->type() == FIELD_TYPE_TIMESTAMP)
+        field->field_length= new_mode ? 19 :
+                             ((Field_timestamp *)(field))->orig_field_length;
+    }
+    table->timestamp_mode= new_mode;
+  }
+#endif
   /* These variables are also set in reopen_table() */
   table->tablenr=thd->current_tablenr++;
   table->used_fields=0;

sql/sql_parse.cc

@@ -3229,7 +3229,18 @@ bool add_field_to_list(char *field_name, enum_field_types type,
     }
     break;
   case FIELD_TYPE_TIMESTAMP:
+#if MYSQL_VERSION_ID < 40100
+    /*
+      When in in --new mode, we should create TIMESTAMP(19) fields by default;
+      otherwise we will have problems with ALTER TABLE changing lengths of
+      existing TIMESTAMP fields to 19 and adding new fields with length 14.
+    */
+    if (thd->variables.new_mode)
+      new_field->length= 19;
+    else if (!length)
+#else
     if (!length)
+#endif
       new_field->length= 14;			// Full date YYYYMMDDHHMMSS
     else if (new_field->length != 19)
     {

sql/table.h

@@ -106,6 +106,14 @@ struct st_table {
 	*found_next_number_field,	/* Set on open */
         *rowid_field;
   Field_timestamp *timestamp_field;
+#if MYSQL_VERSION_ID < 40100
+  /*
+    Indicates whenever we have to set field_length members of all TIMESTAMP
+    fields to 19 (to honour 'new_mode' variable) or to original
+    field_length values.
+  */
+  my_bool timestamp_mode;
+#endif
   my_string comment;			/* Comment about table */
   REGINFO reginfo;			/* field connections */
   MEM_ROOT mem_root;