Fixed bug with GROUP BY on NULL fields.

(Merge of code from 4.0)


Docs/manual.texi:
  Changelog
include/my_base.h:
  Fixed bug with GROUP BY on NULL fields.
include/mysql_com.h:
  Fixed bug with GROUP BY on NULL fields.
myisam/mi_search.c:
  Fixed bug with GROUP BY on NULL fields.
myisam/mi_write.c:
  Fixed bug with GROUP BY on NULL fields.
mysql-test/r/group_by.result:
  Fixed bug with GROUP BY on NULL fields.
mysql-test/t/group_by.test:
  Fixed bug with GROUP BY on NULL fields.
sql/sql_base.cc:
  Removed some not-needed comments in the trace file
sql/sql_select.cc:
  Fixed bug with GROUP BY on NULL fields.

Docs/manual.texi

@@ -46928,6 +46928,9 @@ not yet 100% confident in this code.
 @appendixsubsec Changes in release 3.23.52
 @itemize @bullet
 @item
+Fixed problem with @code{GROUP BY} on result with expression that created a
+@code{BLOB} field.
+@item
 Fixed problem with privilege tables when downgrading from 4.0.2 to 3.23.
 @item
 Fixed thread bug in @code{SLAVE START} and @code{SLAVE STOP}.

include/my_base.h

@@ -134,6 +134,7 @@ enum ha_base_keytype {
 #define HA_BINARY_PACK_KEY	 32	/* Packing of all keys to prev key */
 #define HA_FULLTEXT		128     /* SerG: for full-text search */
 #define HA_UNIQUE_CHECK		256	/* Check the key for uniqueness */
+#define HA_NULL_ARE_EQUAL	2048	/* NULL in key are cmp as equal */
 
 	/* Automatic bits in key-flag */
 
@@ -235,6 +236,7 @@ enum ha_base_keytype {
 #define SEARCH_UPDATE	64
 #define SEARCH_PREFIX	128
 #define SEARCH_LAST	256
+#define SEARCH_NULL_ARE_EQUAL 32768	/* NULL in keys are equal */
 
 	/* bits in opt_flag */
 #define QUICK_USED	1

include/mysql_com.h

@@ -110,6 +110,9 @@ typedef struct st_vio Vio;
 #endif
 #endif
 
+#define MAX_CHAR_WIDTH		255	/* Max length for a CHAR colum */
+#define MAX_BLOB_WIDTH		8192	/* Default width for blob */
+
 typedef struct st_net {
   Vio* vio;
   my_socket fd;					/* For Perl DBI/dbd */

myisam/mi_search.c

@@ -107,8 +107,9 @@ int _mi_search(register MI_INFO *info, register MI_KEYDEF *keyinfo,
   }
   else
   {
-    if (nextflag & SEARCH_FIND && (!(keyinfo->flag & HA_NOSAME)
-				   || key_len) && nod_flag)
+    if ((nextflag & SEARCH_FIND) && nod_flag &&
+	((keyinfo->flag & (HA_NOSAME | HA_NULL_PART)) != HA_NOSAME ||
+	 key_len))
     {
       if ((error=_mi_search(info,keyinfo,key,key_len,SEARCH_FIND,
 			    _mi_kpos(nod_flag,keypos))) >= 0 ||

myisam/mi_write.c

@@ -263,7 +263,11 @@ static int w_search(register MI_INFO *info, register MI_KEYDEF *keyinfo,
   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 */
 

mysql-test/r/group_by.result

@@ -68,3 +68,19 @@ One	Two	sum(Four)
 1	1	16
 1	2	16
 1	3	16
+xID	xID1
+1	1
+2	2
+2	2
+3	134
+3	134
+3	134
+4	185
+4	185
+4	185
+4	185
+xID	xID1	Level
+1	1	*
+2	2	**
+3	134	***
+4	185	****

mysql-test/t/group_by.test

@@ -259,3 +259,14 @@ insert into t1 values (1,3,3,4);
 insert into t1 values (1,3,4,4);
 select One, Two, sum(Four) from t1 group by One,Two;
 drop table if exists t1;
+
+#
+# The GROUP BY returned rows in wrong order in 3.23.51
+#
+
+CREATE TABLE t1 (ID1 int, ID2 int, ID int NOT NULL AUTO_INCREMENT,PRIMARY KEY(ID
+));
+insert into t1 values (1,244,NULL),(2,243,NULL),(134,223,NULL),(185,186,NULL);
+select S.ID as xID, S.ID1 as xID1 from t1 as S left join t1 as yS  on S.ID1 between yS.ID1 and yS.ID2;
+select S.ID as xID, S.ID1 as xID1, repeat('*',count(distinct yS.ID)) as Level from t1 as S left join t1 as yS  on S.ID1 between yS.ID1 and yS.ID2 group by xID order by xID1;
+drop table t1;

sql/sql_base.cc

@@ -2222,18 +2222,18 @@ int setup_ftfuncs(THD *thd)
   return 0;
 }
 
+
 int init_ftfuncs(THD *thd, bool no_order)
 {
-  List_iterator<Item_func_match> li(thd->lex.ftfunc_list);
-  Item_func_match *ifm;
-  DBUG_PRINT("info",("Performing FULLTEXT search"));
-  thd->proc_info="FULLTEXT initialization";
-
-  while ((ifm=li++))
+  if (thd->lex.ftfunc_list.elements)
   {
-    ifm->init_search(no_order);
-  }
+    List_iterator<Item_func_match> li(thd->lex.ftfunc_list);
+    Item_func_match *ifm;
+    DBUG_PRINT("info",("Performing FULLTEXT search"));
+    thd->proc_info="FULLTEXT initialization";
 
+    while ((ifm=li++))
+      ifm->init_search(no_order);
+  }
   return 0;
 }
-

sql/sql_select.cc

@@ -153,7 +153,7 @@ mysql_select(THD *thd,TABLE_LIST *tables,List<Item> &fields,COND *conds,
 	     uint select_options,select_result *result)
 {
   TABLE		*tmp_table;
-  int		error,tmp;
+  int		error, tmp_error;
   bool		need_tmp,hidden_group_fields;
   bool		simple_order,simple_group,no_order;
   Item::cond_result cond_value;
@@ -380,9 +380,9 @@ mysql_select(THD *thd,TABLE_LIST *tables,List<Item> &fields,COND *conds,
       thd->fatal_error)
     goto err;
   thd->proc_info="preparing";
-  if ((tmp=join_read_const_tables(&join)) > 0)
+  if ((tmp_error=join_read_const_tables(&join)) > 0)
     goto err;
-  if (tmp && !(select_options & SELECT_DESCRIBE))
+  if (tmp_error && !(select_options & SELECT_DESCRIBE))
   {
     error=return_zero_rows(result,tables,fields,
 			   join.tmp_table_param.sum_func_count != 0 &&
@@ -701,9 +701,11 @@ 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 */
       }
@@ -3347,7 +3349,11 @@ create_tmp_table(THD *thd,TMP_TABLE_PARAM *param,List<Item> &fields,
     if (!param->quick_group)
       group=0;					// Can't use group key
     else for (ORDER *tmp=group ; tmp ; tmp=tmp->next)
+    {
       (*tmp->item)->marker=4;			// Store null in key
+      if ((*tmp->item)->max_length >= MAX_CHAR_WIDTH)
+	using_unique_constraint=1;
+    }
     if (param->group_length >= MAX_BLOB_WIDTH)
       using_unique_constraint=1;
     if (group)
@@ -3477,7 +3483,7 @@ create_tmp_table(THD *thd,TMP_TABLE_PARAM *param,List<Item> &fields,
   field_count= (uint) (reg_field - table->field);
 
   /* If result table is small; use a heap */
-  if (blob_count || using_unique_constraint ||
+  if (blob_count || using_unique_constraint || group_null_items ||
       (select_options & (OPTION_BIG_TABLES | SELECT_SMALL_RESULT)) ==
       OPTION_BIG_TABLES)
   {
@@ -3499,7 +3505,7 @@ create_tmp_table(THD *thd,TMP_TABLE_PARAM *param,List<Item> &fields,
   if (blob_count == 0)
   {
     /* We need to ensure that first byte is not 0 for the delete link */
-    if (hidden_null_count)
+    if (param->hidden_field_count)
       hidden_null_count++;
     else
       null_count++;
@@ -3633,14 +3639,17 @@ 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
-	     just before the column and extend the key to cover the null bit
+	    To be able to group on NULL, we reserve place in group_buff
+	    for the NULL flag just before the column.
+	    The field data is after this flag.
+	    The NULL flag is updated by 'end_update()' and 'end_write()'
 	  */
-	  *group_buff= 0;			// Init null byte
-	  key_part_info->offset--;
-	  key_part_info->length++;
-	  group->field->move_field((char*) group_buff+1, (uchar*) group_buff,
-				   1);
+	  keyinfo->flags|= HA_NULL_ARE_EQUAL;	// def. that NULL == NULL
+	  key_part_info->null_bit=field->null_bit;
+	  key_part_info->null_offset= (uint) (field->null_ptr -
+					      (uchar*) table->record[0]);
+	  group->field->move_field((char*) ++group->buff);
+	  group_buff++;
 	}
 	else
 	  group->field->move_field((char*) group_buff);
@@ -3820,11 +3829,17 @@ 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 &&
-	  !(field->flags & NOT_NULL_FLAG))
+      if (!(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;
       }
     }
   }
@@ -4797,8 +4812,9 @@ 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],