A fix (bug #8489: Strange auto_increment behaviour with HEAP table).

heap/hp_create.c:
  A fix (bug #8489: Strange auto_increment behaviour with HEAP table).
  Handle autoincrement keys MyISAM-way.
include/heap.h:
  A fix (bug #8489: Strange auto_increment behaviour with HEAP table).
  Handle autoincrement keys MyISAM-way.
sql/ha_heap.cc:
  A fix (bug #8489: Strange auto_increment behaviour with HEAP table).
  Handle autoincrement keys MyISAM-way.

heap/hp_create.c

@@ -137,6 +137,8 @@ int heap_create(const char *name, uint keys, HP_KEYDEF *keydef,
 	keyinfo->write_key= hp_write_key;
         keyinfo->hash_buckets= 0;
       }
+      if ((keyinfo->flag & HA_AUTO_KEY) && create_info->with_auto_increment)
+        share->auto_key= i + 1;
     }
     share->min_records= min_records;
     share->max_records= max_records;
@@ -147,7 +149,6 @@ int heap_create(const char *name, uint keys, HP_KEYDEF *keydef,
     share->keys= keys;
     share->max_key_length= max_length;
     share->changed= 0;
-    share->auto_key= create_info->auto_key;
     share->auto_key_type= create_info->auto_key_type;
     share->auto_increment= create_info->auto_increment;
     /* Must be allocated separately for rename to work */

include/heap.h

@@ -183,10 +183,10 @@ typedef struct st_heap_info
 
 typedef struct st_heap_create_info
 {
-  uint auto_key;
   uint auto_key_type;
   ulong max_table_size;
   ulonglong auto_increment;
+  my_bool with_auto_increment;
 } HP_CREATE_INFO;
 
 	/* Prototypes for heap-functions */

mysql-test/r/heap.result

@@ -249,3 +249,45 @@ a
 3
 2
 drop table t1;
+create table t1 (a bigint unsigned auto_increment primary key, b int,
+key (b, a)) engine=heap;
+insert t1 (b) values (1);
+insert t1 (b) values (1);
+insert t1 (b) values (1);
+insert t1 (b) values (1);
+insert t1 (b) values (1);
+insert t1 (b) values (1);
+insert t1 (b) values (1);
+insert t1 (b) values (1);
+select * from t1;
+a	b
+1	1
+2	1
+3	1
+4	1
+5	1
+6	1
+7	1
+8	1
+drop table t1;
+create table t1 (a int not null, b int not null auto_increment,
+primary key(a, b), key(b)) engine=heap;
+insert t1 (a) values (1);
+insert t1 (a) values (1);
+insert t1 (a) values (1);
+insert t1 (a) values (1);
+insert t1 (a) values (1);
+insert t1 (a) values (1);
+insert t1 (a) values (1);
+insert t1 (a) values (1);
+select * from t1;
+a	b
+1	1
+1	2
+1	3
+1	4
+1	5
+1	6
+1	7
+1	8
+drop table t1;

mysql-test/t/heap.test

@@ -195,3 +195,32 @@ delete from t1 where a is null;
 insert into t1 values ('2'), ('3');
 select * from t1;
 drop table t1;
+
+#
+# Bug #8489: Strange auto_increment behaviour
+#
+
+create table t1 (a bigint unsigned auto_increment primary key, b int,
+  key (b, a)) engine=heap;
+insert t1 (b) values (1);
+insert t1 (b) values (1);
+insert t1 (b) values (1);
+insert t1 (b) values (1);
+insert t1 (b) values (1);
+insert t1 (b) values (1);
+insert t1 (b) values (1);
+insert t1 (b) values (1);
+select * from t1;                                                               
+drop table t1;
+create table t1 (a int not null, b int not null auto_increment,
+  primary key(a, b), key(b)) engine=heap;
+insert t1 (a) values (1);
+insert t1 (a) values (1);
+insert t1 (a) values (1);
+insert t1 (a) values (1);
+insert t1 (a) values (1);
+insert t1 (a) values (1);
+insert t1 (a) values (1);
+insert t1 (a) values (1);
+select * from t1;                                                               
+drop table t1;

sql/ha_heap.cc

@@ -446,6 +446,7 @@ int ha_heap::create(const char *name, TABLE *table_arg,
   HA_KEYSEG *seg;
   char buff[FN_REFLEN];
   int error;
+  bool found_real_auto_increment= 0;
 
   for (key= parts= 0; key < table_arg->keys; key++)
     parts+= table_arg->key_info[key].key_parts;
@@ -506,17 +507,20 @@ int ha_heap::create(const char *name, TABLE *table_arg,
 	seg->null_bit= 0;
 	seg->null_pos= 0;
       }
+      // We have to store field->key_type() as seg->type can differ from it
       if (field->flags & AUTO_INCREMENT_FLAG)
-      {
-	auto_key= key + 1;
 	auto_key_type= field->key_type();
-      }
     }
   }
+  if (table_arg->found_next_number_field)
+  {
+    keydef[table_arg->next_number_index].flag|= HA_AUTO_KEY;
+    found_real_auto_increment= table_arg->next_number_key_offset == 0;
+  }
   mem_per_row+= MY_ALIGN(table_arg->reclength + 1, sizeof(char*));
   HP_CREATE_INFO hp_create_info;
-  hp_create_info.auto_key= auto_key;
   hp_create_info.auto_key_type= auto_key_type;
+  hp_create_info.with_auto_increment= found_real_auto_increment;
   hp_create_info.auto_increment= (create_info->auto_increment_value ?
 				  create_info->auto_increment_value - 1 : 0);
   hp_create_info.max_table_size=current_thd->variables.max_heap_table_size;