Add support for NULL=NULL in keys (Used in GROUP BY optimization)

Add ISAM to Windows version
Fix of test results
Fixes for NULL keys in HEAP tables.


Docs/manual.texi:
  Changelog
heap/hp_open.c:
  Add support for NULL=NULL in keys (for GROUP BY)
heap/hp_rkey.c:
  Cleanup
heap/hp_write.c:
  Cleanup
include/config-win.h:
  Add ISAM to Windows version
include/my_base.h:
  Add support for NULL=NULL in keys (for GROUP BY)
libmysqld/Makefile.am:
  Rename of innobase to innodb
myisam/mi_write.c:
  Add support for NULL=NULL in keys (for GROUP BY)
BitKeeper/etc/ignore:
  Added libmysqld/ha_innodb.cc to the ignore list
mysql-test/r/group_by.result:
  Test of NULL keys in HEAP tables
mysql-test/r/heap.result:
  Test of NULL keys in HEAP tables
mysql-test/r/null.result:
  Cleanup
mysql-test/r/order_by.result:
  Fix for result of new ORDER BY optimization
mysql-test/t/group_by.test:
  Test of NULL keys in HEAP tables
mysql-test/t/heap.test:
  Test of NULL keys in HEAP tables
mysql-test/t/null.test:
  Cleanup
sql/ha_heap.cc:
  Add support of NULL keys
sql/item_strfunc.h:
  Fix for BINARY and CAST functions
sql/item_timefunc.h:
  Fix for BINARY and CAST functions
sql/sql_parse.cc:
  Cleanup
sql/sql_select.cc:
  Add support for NULL=NULL in keys (for GROUP BY)

.bzrignore

@@ -451,3 +451,4 @@ vio/test-ssl
 vio/test-sslclient
 vio/test-sslserver
 vio/viotest-ssl
+libmysqld/ha_innodb.cc

Docs/manual.texi

@@ -48121,10 +48121,12 @@ Our TODO section contains what we plan to have in 4.0. @xref{TODO MySQL 4.0}.
 
 @itemize @bullet
 @item
+Fixed bug in @code{GROUP BY BINARY column}
+@item
 Added support for @code{NULL} keys in HEAP tables.
 @item
 Use index for @code{ORDER BY} in queries of type:
-@code{SELECT * FROM t1 WHERE key_part1=1 ORDER BY key_part1 DESC,key_part2 DESC}
+@code{SELECT * FROM t WHERE key_part1=1 ORDER BY key_part1 DESC,key_part2 DESC}
 @item
 Fixed bug in @code{FLUSH QUERY CACHE}.
 @item

heap/hp_open.c

@@ -46,7 +46,8 @@ HP_INFO *heap_open(const char *name, int mode, uint keys, HP_KEYDEF *keydef,
       for (j=length=0 ; j < keydef[i].keysegs; j++)
       {
 	length+=keydef[i].seg[j].length;
-	if (keydef[i].seg[j].null_bit)
+	if (keydef[i].seg[j].null_bit &&
+	    !(keydef[i].flag & HA_NULL_ARE_EQUAL))
 	  keydef[i].flag |= HA_NULL_PART_KEY;
       }
       keydef[i].length=length;

heap/hp_rkey.c

@@ -20,7 +20,7 @@ int heap_rkey(HP_INFO *info, byte *record, int inx, const byte *key)
 {
   byte *pos;
   HP_SHARE *share=info->s;
-  DBUG_ENTER("hp_rkey");
+  DBUG_ENTER("heap_rkey");
   DBUG_PRINT("enter",("base: %lx  inx: %d",info,inx));
 
   if ((uint) inx >= share->keys)

heap/hp_write.c

@@ -238,7 +238,7 @@ int _hp_write_key(register HP_SHARE *info, HP_KEYDEF *keyinfo,
       _hp_movelink(pos,gpos,empty);
     }
 
-    /* Check if dupplicated keys */
+    /* Check if duplicated keys */
     if ((keyinfo->flag & HA_NOSAME) && pos == gpos &&
 	(!(keyinfo->flag & HA_NULL_PART_KEY) ||
 	 !hp_if_null_in_key(keyinfo, record)))

include/config-win.h

@@ -255,6 +255,8 @@ inline double ulonglong2double(ulonglong value)
 #define HAVE_COMPRESS
 #define HAVE_CREATESEMAPHORE
 
+#define HAVE_ISAM		/* We want to have support for ISAM in 4.0 */
+
 #ifdef NOT_USED
 #define HAVE_SNPRINTF		/* Gave link error */
 #define _snprintf snprintf

include/my_base.h

@@ -150,6 +150,7 @@ enum ha_base_keytype {
 #define HA_FULLTEXT		128     /* SerG: for full-text search */
 #define HA_UNIQUE_CHECK		256	/* Check the key for uniqueness */
 #define HA_SPATIAL		1024    /* Alex Barkov: for spatial search */
+#define HA_NULL_ARE_EQUAL	2048	/* NULL in key are cmp as equal */
 
 
 	/* Automatic bits in key-flag */
@@ -260,6 +261,7 @@ enum ha_base_keytype {
 #define MBR_DISJOINT    4096
 #define MBR_EQUAL       8192
 #define MBR_DATA        16384
+#define SEARCH_NULL_ARE_EQUAL 32768	/* NULL in keys are equal */
 
 	/* bits in opt_flag */
 #define QUICK_USED	1

libmysqld/Makefile.am

@@ -38,7 +38,7 @@ libmysqlsources =	errmsg.c get_password.c password.c
 noinst_HEADERS =	embedded_priv.h
 
 sqlsources = convert.cc derror.cc field.cc field_conv.cc filesort.cc \
-	ha_innobase.cc ha_berkeley.cc ha_heap.cc ha_isam.cc ha_isammrg.cc \
+	ha_innodb.cc ha_berkeley.cc ha_heap.cc ha_isam.cc ha_isammrg.cc \
 	ha_myisam.cc ha_myisammrg.cc handler.cc sql_handler.cc \
 	hostname.cc init.cc \
 	item.cc item_buff.cc item_cmpfunc.cc item_create.cc \

myisam/mi_write.c

@@ -25,7 +25,8 @@
 
 	/* Functions declared in this file */
 
-static int w_search(MI_INFO *info,MI_KEYDEF *keyinfo,uchar *key,
+static int w_search(MI_INFO *info,MI_KEYDEF *keyinfo,
+		    uint comp_flag, uchar *key,
 		    uint key_length, my_off_t pos, uchar *father_buff,
 		    uchar *father_keypos, my_off_t father_page,
 		    my_bool insert_last);
@@ -245,10 +246,23 @@ int _mi_ck_write_btree(register MI_INFO *info, uint keynr, uchar *key,
 		       uint key_length)
 {
   int error;
+  uint comp_flag;
+  MI_KEYDEF *keyinfo=info->s->keyinfo+keynr;
   DBUG_ENTER("_mi_ck_write_btree");
 
+  if (keyinfo->flag & HA_SORT_ALLOWS_SAME)
+    comp_flag=SEARCH_BIGGER;			/* Put after same key */
+  else if (keyinfo->flag & HA_NOSAME)
+  {
+    comp_flag=SEARCH_FIND | SEARCH_UPDATE;	/* No dupplicates */
+    if (keyinfo->flag & HA_NULL_ARE_EQUAL)
+      comp_flag|= SEARCH_NULL_ARE_EQUAL;
+  }
+  else
+    comp_flag=SEARCH_SAME;			/* Keys in rec-pos order */
+
   if (info->s->state.key_root[keynr] == HA_OFFSET_ERROR ||
-      (error=w_search(info,info->s->keyinfo+keynr,key, key_length,
+      (error=w_search(info, keyinfo, comp_flag, key, key_length,
 		      info->s->state.key_root[keynr], (uchar *) 0, (uchar*) 0,
 		      (my_off_t) 0, 1)) > 0)
     error=_mi_enlarge_root(info,keynr,key);
@@ -291,13 +305,12 @@ int _mi_enlarge_root(register MI_INFO *info, uint keynr, uchar *key)
 	*/
 
 static int w_search(register MI_INFO *info, register MI_KEYDEF *keyinfo,
-		    uchar *key, uint key_length, my_off_t page,
+		    uint comp_flag, uchar *key, uint key_length, my_off_t page,
-		    uchar *father_buff,
+		    uchar *father_buff, uchar *father_keypos,
-		    uchar *father_keypos, my_off_t father_page,
+		    my_off_t father_page, my_bool insert_last)
-		    my_bool insert_last)
 {
   int error,flag;
-  uint comp_flag,nod_flag, search_key_length;
+  uint nod_flag, search_key_length;
   uchar *temp_buff,*keypos;
   uchar keybuff[MI_MAX_KEY_BUFF];
   my_bool was_last_key;
@@ -305,17 +318,7 @@ static int w_search(register MI_INFO *info, register MI_KEYDEF *keyinfo,
   DBUG_ENTER("w_search");
   DBUG_PRINT("enter",("page: %ld",page));
 
-  search_key_length=USE_WHOLE_KEY;
+  search_key_length= (comp_flag & SEARCH_FIND) ? key_length : USE_WHOLE_KEY;
-  if (keyinfo->flag & HA_SORT_ALLOWS_SAME)
-    comp_flag=SEARCH_BIGGER;			/* Put after same key */
-  else if (keyinfo->flag & HA_NOSAME)
-  {
-    comp_flag=SEARCH_FIND | SEARCH_UPDATE;	/* No dupplicates */
-    search_key_length= key_length;
-  }
-  else
-    comp_flag=SEARCH_SAME;			/* Keys in rec-pos order */
-
   if (!(temp_buff= (uchar*) my_alloca((uint) keyinfo->block_length+
 				      MI_MAX_KEY_BUFF*2)))
     DBUG_RETURN(-1);
@@ -344,7 +347,7 @@ static int w_search(register MI_INFO *info, register MI_KEYDEF *keyinfo,
     insert_last=0;
   next_page=_mi_kpos(nod_flag,keypos);
   if (next_page == HA_OFFSET_ERROR ||
-      (error=w_search(info,keyinfo,key,key_length,next_page,
+      (error=w_search(info, keyinfo, comp_flag, key, key_length, next_page,
 		      temp_buff, keypos, page, insert_last)) >0)
   {
     error=_mi_insert(info,keyinfo,key,temp_buff,keypos,keybuff,father_buff,
@@ -759,15 +762,17 @@ static int keys_compare(bulk_insert_param *param, uchar *key1, uchar *key2)
 {
   uint not_used;
   return _mi_key_cmp(param->info->s->keyinfo[param->keynr].seg,
-              key1, key2, USE_WHOLE_KEY, SEARCH_SAME, &not_used);
+		     key1, key2, USE_WHOLE_KEY, SEARCH_SAME,
+		     &not_used);
 }
 
 
 static int keys_free(uchar *key, TREE_FREE mode, bulk_insert_param *param)
 {
-  /* probably I can use info->lastkey here, but I'm not sure,
+  /*
+    Probably I can use info->lastkey here, but I'm not sure,
     and to be safe I'd better use local lastkey.
-     Monty, feel free to comment on this */
+  */
   uchar lastkey[MI_MAX_KEY_BUFF];
   uint keylen;
   MI_KEYDEF *keyinfo;
@@ -794,6 +799,7 @@ static int keys_free(uchar *key, TREE_FREE mode, bulk_insert_param *param)
   return -1;
 }
 
+
 int _mi_init_bulk_insert(MI_INFO *info)
 {
   MYISAM_SHARE *share=info->s;

mysql-test/r/group_by.result

@@ -263,3 +263,84 @@ score	count(*)
 2	1
 1	2
 drop table t1;
+CREATE TABLE t1 (a char(1));
+INSERT INTO t1 VALUES ('A'),('B'),('A'),('B'),('A'),('B'),(NULL),('a'),('b'),(NULL),('A'),('B'),(NULL);
+SELECT a FROM t1 GROUP BY a;
+a
+NULL
+A
+B
+SELECT a,count(*) FROM t1 GROUP BY a;
+a	count(*)
+NULL	3
+A	5
+B	5
+SELECT a FROM t1 GROUP BY binary a;
+a
+NULL
+A
+B
+a
+b
+SELECT a,count(*) FROM t1 GROUP BY binary a;
+a	count(*)
+NULL	3
+A	4
+B	4
+a	1
+b	1
+SELECT binary a FROM t1 GROUP BY 1;
+binary a
+NULL
+A
+B
+a
+b
+SELECT binary a,count(*) FROM t1 GROUP BY 1;
+binary a	count(*)
+NULL	3
+A	4
+B	4
+a	1
+b	1
+SET SQL_BIG_TABLES=1;
+SELECT a FROM t1 GROUP BY a;
+a
+NULL
+A
+B
+SELECT a,count(*) FROM t1 GROUP BY a;
+a	count(*)
+NULL	3
+A	5
+B	5
+SELECT a FROM t1 GROUP BY binary a;
+a
+NULL
+A
+B
+a
+b
+SELECT a,count(*) FROM t1 GROUP BY binary a;
+a	count(*)
+NULL	3
+A	4
+B	4
+a	1
+b	1
+SELECT binary a FROM t1 GROUP BY 1;
+binary a
+NULL
+A
+B
+a
+b
+SELECT binary a,count(*) FROM t1 GROUP BY 1;
+binary a	count(*)
+NULL	3
+A	4
+B	4
+a	1
+b	1
+SET SQL_BIG_TABLES=0;
+drop table t1;

mysql-test/r/heap.result

@@ -165,3 +165,29 @@ explain select * from t1 where btn="a" and new_col="a";
 table	type	possible_keys	key	key_len	ref	rows	Extra
 t1	ref	btn	btn	11	const,const	10	where used
 drop table t1;
+CREATE TABLE t1 (
+a int default NULL,
+b int default NULL,
+KEY a (a),
+UNIQUE b (b)
+) type=heap;
+INSERT INTO t1 VALUES (NULL,99),(99,NULL),(1,1),(2,2),(1,3);
+SELECT * FROM t1 WHERE a=NULL;
+a	b
+explain SELECT * FROM t1 WHERE a IS NULL;
+table	type	possible_keys	key	key_len	ref	rows	Extra
+t1	ref	a	a	5	const	10	where used
+SELECT * FROM t1 WHERE a<=>NULL;
+a	b
+NULL	99
+SELECT * FROM t1 WHERE b=NULL;
+a	b
+explain SELECT * FROM t1 WHERE b IS NULL;
+table	type	possible_keys	key	key_len	ref	rows	Extra
+t1	ref	b	b	5	const	1	where used
+SELECT * FROM t1 WHERE b<=>NULL;
+a	b
+99	NULL
+INSERT INTO t1 VALUES (1,3);
+Duplicate entry '3' for key 1
+DROP TABLE t1;

mysql-test/r/null.result

@@ -40,7 +40,6 @@ insert into t1 values (null);
 select * from t1 where x != 0;
 x
 drop table t1;
-DROP TABLE IF EXISTS t1;
 CREATE TABLE t1 (
 indexed_field int default NULL,
 KEY indexed_field (indexed_field)

mysql-test/r/order_by.result

@@ -286,15 +286,15 @@ a	b	c
 1	NULL	NULL
 explain select * from t1 where a = 1 order by a desc, b desc;
 table	type	possible_keys	key	key_len	ref	rows	Extra
-t1	ref	a	a	4	const	5	where used; Using index; Using filesort
+t1	ref	a	a	4	const	5	where used; Using index
 select * from t1 where a = 1 order by a desc, b desc;
 a	b	c
 1	3	b
+1	1	b
+1	1	b
 1	1	NULL
-1	1	b
-1	1	b
-1	NULL	NULL
 1	NULL	b
+1	NULL	NULL
 explain select * from t1 where a = 1 and b is null order by a desc, b desc;
 table	type	possible_keys	key	key_len	ref	rows	Extra
 t1	ref	a	a	9	const,const	2	where used; Using index; Using filesort

mysql-test/t/group_by.test

@@ -243,3 +243,26 @@ select sql_big_result spid,sum(userid) from t1 group by spid desc;
 explain select sql_big_result score,count(*) from t1 group by score desc;
 select sql_big_result score,count(*) from t1 group by score desc;
 drop table t1;
+
+#
+# Compare with hash keys
+#
+
+CREATE TABLE t1 (a char(1));
+INSERT INTO t1 VALUES ('A'),('B'),('A'),('B'),('A'),('B'),(NULL),('a'),('b'),(NULL),('A'),('B'),(NULL);
+SELECT a FROM t1 GROUP BY a;
+SELECT a,count(*) FROM t1 GROUP BY a;
+SELECT a FROM t1 GROUP BY binary a;
+SELECT a,count(*) FROM t1 GROUP BY binary a;
+SELECT binary a FROM t1 GROUP BY 1;
+SELECT binary a,count(*) FROM t1 GROUP BY 1;
+# Do the same tests with MyISAM temporary tables
+SET SQL_BIG_TABLES=1;
+SELECT a FROM t1 GROUP BY a;
+SELECT a,count(*) FROM t1 GROUP BY a;
+SELECT a FROM t1 GROUP BY binary a;
+SELECT a,count(*) FROM t1 GROUP BY binary a;
+SELECT binary a FROM t1 GROUP BY 1;
+SELECT binary a,count(*) FROM t1 GROUP BY 1;
+SET SQL_BIG_TABLES=0;
+drop table t1;

mysql-test/t/heap.test

@@ -100,3 +100,25 @@ update t1 set new_col=btn;
 explain select * from t1 where btn="a";
 explain select * from t1 where btn="a" and new_col="a";
 drop table t1;
+
+#
+# Test of NULL keys
+#
+
+CREATE TABLE t1 (
+  a int default NULL,
+  b int default NULL,
+  KEY a (a),
+  UNIQUE b (b)
+) type=heap;
+INSERT INTO t1 VALUES (NULL,99),(99,NULL),(1,1),(2,2),(1,3);
+SELECT * FROM t1 WHERE a=NULL;
+explain SELECT * FROM t1 WHERE a IS NULL;
+SELECT * FROM t1 WHERE a<=>NULL;
+SELECT * FROM t1 WHERE b=NULL;
+explain SELECT * FROM t1 WHERE b IS NULL;
+SELECT * FROM t1 WHERE b<=>NULL;
+
+--error 1062
+INSERT INTO t1 VALUES (1,3);
+DROP TABLE t1;

mysql-test/t/null.test

@@ -25,7 +25,6 @@ drop table t1;
 # Test problem med index on NULL columns and testing with =NULL;
 #
 
-DROP TABLE IF EXISTS t1;
 CREATE TABLE t1 (
   indexed_field int default NULL,
   KEY indexed_field (indexed_field)

sql/ha_heap.cc

@@ -33,7 +33,7 @@ const char **ha_heap::bas_ext() const
 
 int ha_heap::open(const char *name, int mode, uint test_if_locked)
 {
-  uint key,part,parts,mem_per_row=0;
+  uint key,parts,mem_per_row=0;
   ulong max_rows;
   HP_KEYDEF *keydef;
   HP_KEYSEG *seg;
@@ -48,24 +48,27 @@ int ha_heap::open(const char *name, int mode, uint test_if_locked)
   for (key=0 ; key < table->keys ; key++)
   {
     KEY *pos=table->key_info+key;
+    KEY_PART_INFO *key_part=     pos->key_part;
+    KEY_PART_INFO *key_part_end= key_part+pos->key_parts;
+
     mem_per_row += (pos->key_length + (sizeof(char*) * 2));
 
     keydef[key].keysegs=(uint) pos->key_parts;
-    keydef[key].flag = (pos->flags & HA_NOSAME);
+    keydef[key].flag = (pos->flags & (HA_NOSAME | HA_NULL_ARE_EQUAL));
     keydef[key].seg=seg;
 
-    for (part=0 ; part < pos->key_parts ; part++)
+    for (; key_part != key_part_end ; key_part++, seg++)
     {
-      uint flag=pos->key_part[part].key_type;
+      uint flag=key_part->key_type;
-      Field *field=pos->key_part[part].field;
+      Field *field=key_part->field;
       if (!f_is_packed(flag) &&
 	  f_packtype(flag) == (int) FIELD_TYPE_DECIMAL &&
 	  !(flag & FIELDFLAG_BINARY))
 	seg->type= (int) HA_KEYTYPE_TEXT;
       else
 	seg->type= (int) HA_KEYTYPE_BINARY;
-      seg->start=(uint) pos->key_part[part].offset;
+      seg->start=(uint) key_part->offset;
-      seg->length=(uint) pos->key_part[part].length;
+      seg->length=(uint) key_part->length;
       if (field->null_ptr)
       {
 	seg->null_bit=field->null_bit;
@@ -88,6 +91,7 @@ int ha_heap::open(const char *name, int mode, uint test_if_locked)
 		  table->max_rows : max_rows),
 		 table->min_rows);
   my_free((gptr) keydef,MYF(0));
+  if (file)
     info(HA_STATUS_NO_LOCK | HA_STATUS_CONST | HA_STATUS_VARIABLE);
   ref_length=sizeof(HEAP_PTR);
   return (!file ? errno : 0);

sql/item_strfunc.h

@@ -435,7 +435,8 @@ class Item_func_binary :public Item_str_func
 public:
   Item_func_binary(Item *a) :Item_str_func(a) {}
   const char *func_name() const { return "binary"; }
-  String *val_str(String *a) { return (args[0]->val_str(a)); }
+  String *val_str(String *a)
+  { a=args[0]->val_str(a); null_value=args[0]->null_value; return a; }
   void fix_length_and_dec() { binary=1; max_length=args[0]->max_length; }
   void print(String *str) { print_op(str); }
 };

sql/item_timefunc.h

@@ -418,7 +418,8 @@ class Item_typecast :public Item_str_func
 {
 public:
   Item_typecast(Item *a) :Item_str_func(a) {}
-  String *val_str(String *a) { return (args[0]->val_str(a)); }
+  String *val_str(String *a)
+  { a=args[0]->val_str(a); null_value=args[0]->null_value; return a; }
   void fix_length_and_dec() { max_length=args[0]->max_length; }
   void print(String *str);
 };

sql/sql_parse.cc

@@ -557,9 +557,9 @@ pthread_handler_decl(handle_one_connection,arg)
 
   pthread_detach_this_thread();
 
-#if !defined( __WIN__) && !defined(OS2)	/* Win32 calls this in pthread_create */
+#if !defined( __WIN__) && !defined(OS2)	// Win32 calls this in pthread_create
-  if (my_thread_init()) // needed to be called first before we call
+  // The following calls needs to be done before we call DBUG_ macros
-    // DBUG_ macros
+  if (my_thread_init())
   {
     close_connection(&thd->net,ER_OUT_OF_RESOURCES);
     statistic_increment(aborted_connects,&LOCK_thread_count);
@@ -568,13 +568,13 @@ pthread_handler_decl(handle_one_connection,arg)
   }
 #endif
 
-  // handle_one_connection() is the only way a thread would start
+  /*
-  // and would always be on top of the stack
+    handle_one_connection() is the only way a thread would start
-  // therefore, the thread stack always starts at the address of the first
+    and would always be on top of the stack, therefore, the thread
-  // local variable of handle_one_connection, which is thd
+    stack always starts at the address of the first local variable
-  // we need to know the start of the stack so that we could check for
+    of handle_one_connection, which is thd. We need to know the
-  // stack overruns
+    start of the stack so that we could check for stack overruns.
-
+  */
   DBUG_PRINT("info", ("handle_one_connection called by thread %d\n",
 		      thd->thread_id));
   // now that we've called my_thread_init(), it is safe to call DBUG_*
@@ -1216,7 +1216,6 @@ mysql_execute_command(void)
 #endif
   }
   
-  thread_safe_increment(com_stat[lex->sql_command],&LOCK_thread_count);
   /*
     Skip if we are in the slave thread, some table rules have been given
     and the table list says the query should not be replicated

sql/sql_select.cc

@@ -183,7 +183,7 @@ mysql_select(THD *thd,TABLE_LIST *tables,List<Item> &fields,COND *conds,
 	     ulong select_options,select_result *result)
 {
   TABLE		*tmp_table;
-  int		error,tmp;
+  int		error, tmp_error, tmp;
   bool		need_tmp,hidden_group_fields;
   bool		simple_order,simple_group,no_order, skip_sort_order;
   Item::cond_result cond_value;
@@ -678,8 +678,11 @@ mysql_select(THD *thd,TABLE_LIST *tables,List<Item> &fields,COND *conds,
 
     /* Copy data to the temporary table */
     thd->proc_info="Copying to tmp table";
-    if (do_select(&join,(List<Item> *) 0,tmp_table,0))
+    if ((tmp_error=do_select(&join,(List<Item> *) 0,tmp_table,0)))
+    {
+      error=tmp_error;
       goto err;					/* purecov: inspected */
+    }
     if (join.having)
       join.having=having=0;			// Allready done
 
@@ -752,9 +755,11 @@ mysql_select(THD *thd,TABLE_LIST *tables,List<Item> &fields,COND *conds,
 	group=0;
       }
       thd->proc_info="Copying to group table";
+      tmp_error= -1;
       if (make_sum_func_list(&join,all_fields) ||
-	  do_select(&join,(List<Item> *) 0,tmp_table2,0))
+	  (tmp_error=do_select(&join,(List<Item> *) 0,tmp_table2,0)))
       {
+	error=tmp_error;
 	free_tmp_table(thd,tmp_table2);
 	goto err;				/* purecov: inspected */
       }
@@ -3736,14 +3741,16 @@ create_tmp_table(THD *thd,TMP_TABLE_PARAM *param,List<Item> &fields,
 	if (maybe_null)
 	{
 	  /*
-	    To be able to group on NULL, we move the null bit to be
+	    To be able to group on NULL, we reserve place in group_buff
-	    just before the column.
+	    for the NULL flag just before the column.
-	    The null byte is updated by 'end_update()' 
+	    The field data is after this flag.
+	    The NULL flag is updated by 'end_update()' and 'end_write()'
 	  */
-	  key_part_info->null_bit=1;
+	  keyinfo->flags|= HA_NULL_ARE_EQUAL;	// def. that NULL == NULL
-	  key_part_info->null_offset= key_part_info->offset-1;
+	  key_part_info->null_bit=field->null_bit;
-	  group->field->move_field((char*) group_buff+1, (uchar*) group_buff,
+	  key_part_info->null_offset= (uint) (field->null_ptr -
-				   1);
+					      (uchar*) table->record[0]);
+	  group->field->move_field((char*) ++group->buff);
 	}
 	else
 	  group->field->move_field((char*) group_buff);
@@ -3923,11 +3930,17 @@ static bool create_myisam_tmp_table(TABLE *table,TMP_TABLE_PARAM *param,
 	    keyinfo->key_part[i].length > 4)
 	  seg->flag|=HA_SPACE_PACK;
       }
-      if (using_unique_constraint &&
+      if (!(field->flags & NOT_NULL_FLAG))
-	  !(field->flags & NOT_NULL_FLAG))
       {
 	seg->null_bit= field->null_bit;
 	seg->null_pos= (uint) (field->null_ptr - (uchar*) table->record[0]);
+	/*
+	  We are using a GROUP BY on something that contains NULL
+	  In this case we have to tell MyISAM that two NULL should
+	  on INSERT be compared as equal
+	*/
+	if (!using_unique_constraint)
+	  keydef.flag|= HA_NULL_ARE_EQUAL;
       }
     }
   }
@@ -4065,9 +4078,12 @@ bool create_myisam_from_heap(TABLE *table, TMP_TABLE_PARAM *param, int error,
 }
 
 
-/*****************************************************************************
+/****************************************************************************
-**	Make a join of all tables and write it on socket or to table
+  Make a join of all tables and write it on socket or to table
-*****************************************************************************/
+  Return:  0 if ok
+           1 if error is sent
+          -1 if error should be sent
+****************************************************************************/
 
 static int
 do_select(JOIN *join,List<Item> *fields,TABLE *table,Procedure *procedure)
@@ -4144,15 +4160,21 @@ do_select(JOIN *join,List<Item> *fields,TABLE *table,Procedure *procedure)
     if (error == -3)
       error=0;					/* select_limit used */
   }
+
+  /* Return 1 if error is sent;  -1 if error should be sent */
   if (error < 0)
+  {
     join->result->send_error(0,NullS);		/* purecov: inspected */
+    error=1;					// Error sent
+  }
   else
   {
+    error=0;
     if (!table)					// If sending data to client
     {
       join_free(join);				// Unlock all cursors
       if (join->result->send_eof())
-	error= -1;
+	error= 1;				// Don't send error
     }
     DBUG_PRINT("info",("%ld records output",join->send_records));
   }
@@ -4169,10 +4191,10 @@ do_select(JOIN *join,List<Item> *fields,TABLE *table,Procedure *procedure)
       my_errno=tmp;
       error= -1;
     }
-    if (error != old_error)
+    if (error == -1)
       table->file->print_error(my_errno,MYF(0));
   }
-  DBUG_RETURN(error < 0);
+  DBUG_RETURN(error);
 }
 
 
@@ -4926,6 +4948,7 @@ end_write(JOIN *join, JOIN_TAB *join_tab __attribute__((unused)),
     copy_fields(&join->tmp_table_param);
     copy_funcs(join->tmp_table_param.funcs);
 
+#ifdef TO_BE_DELETED
     if (!table->uniques)			// If not unique handling
     {
       /* Copy null values from group to row */
@@ -4936,10 +4959,11 @@ end_write(JOIN *join, JOIN_TAB *join_tab __attribute__((unused)),
 	if (item->maybe_null)
 	{
 	  Field *field=item->tmp_table_field();
-	  field->ptr[-1]= (byte) (field->is_null() ? 0 : 1);
+	  field->ptr[-1]= (byte) (field->is_null() ? 1 : 0);
 	}
       }
     }
+#endif
     if (!join->having || join->having->val_int())
     {
       join->found_records++;
@@ -4994,8 +5018,9 @@ end_update(JOIN *join, JOIN_TAB *join_tab __attribute__((unused)),
   {
     Item *item= *group->item;
     item->save_org_in_field(group->field);
+    /* Store in the used key if the field was 0 */
     if (item->maybe_null)
-      group->buff[0]=item->null_value ? 0: 1;	// Save reversed value
+      group->buff[-1]=item->null_value ? 1 : 0;
   }
   // table->file->index_init(0);
   if (!table->file->index_read(table->record[1],