Bug#30384: Having SQL_BUFFER_RESULT option in the CREATE .. KEY(..) .. SELECT

led to creating corrupted index.

Corrected fix. The new method called prepare2 is added to the select_create
class. As all preparations are done by the select_create::prepare function
it doesn't do anything. Slightly changed algorithm of calling the 
start_bulk_insert function. Now it's called from the select_insert::prepare2
function when the SQL_BUFFER_RESULT flags is set.
The is_bulk_insert_mode flag is removed as it is not needed anymore.

sql/sql_class.h

@@ -2029,14 +2029,13 @@ class select_insert :public select_result_interceptor {
   ulonglong last_insert_id;
   COPY_INFO info;
   bool insert_into_view;
-  bool is_bulk_insert_mode;
   select_insert(TABLE_LIST *table_list_par,
 		TABLE *table_par, List<Item> *fields_par,
 		List<Item> *update_fields, List<Item> *update_values,
 		enum_duplicates duplic, bool ignore);
   ~select_insert();
   int prepare(List<Item> &list, SELECT_LEX_UNIT *u);
-  int prepare2(void);
+  virtual int prepare2(void);
   bool send_data(List<Item> &items);
   virtual void store_values(List<Item> &values);
   void send_error(uint errcode,const char *err);
@@ -2071,6 +2070,7 @@ public:
   void send_error(uint errcode,const char *err);
   bool send_eof();
   void abort();
+  int prepare2(void) { return 0; }
 };
 
 #include <myisam.h>

sql/sql_insert.cc

@@ -2645,8 +2645,7 @@ select_insert::select_insert(TABLE_LIST *table_list_par, TABLE *table_par,
                              bool ignore_check_option_errors)
   :table_list(table_list_par), table(table_par), fields(fields_par),
    last_insert_id(0),
-   insert_into_view(table_list_par && table_list_par->view != 0),
-   is_bulk_insert_mode(FALSE)
+   insert_into_view(table_list_par && table_list_par->view != 0)
 {
   bzero((char*) &info,sizeof(info));
   info.handle_duplicates= duplic;
@@ -2755,14 +2754,14 @@ select_insert::prepare(List<Item> &values, SELECT_LEX_UNIT *u)
     Is table which we are changing used somewhere in other parts of
     query
   */
-  if (!(lex->current_select->options & OPTION_BUFFER_RESULT) &&
-      unique_table(thd, table_list, table_list->next_global, 0))
+  if (unique_table(thd, table_list, table_list->next_global, 0))
   {
     /* Using same table for INSERT and SELECT */
     lex->current_select->options|= OPTION_BUFFER_RESULT;
     lex->current_select->join->select_options|= OPTION_BUFFER_RESULT;
   }
-  else if (!thd->prelocked_mode)
+  else if (!(lex->current_select->options & OPTION_BUFFER_RESULT) &&
+           !thd->prelocked_mode)
   {
     /*
       We must not yet prepare the result table if it is the same as one of the 
@@ -2831,11 +2830,8 @@ int select_insert::prepare2(void)
 {
   DBUG_ENTER("select_insert::prepare2");
   if (thd->lex->current_select->options & OPTION_BUFFER_RESULT &&
-      !thd->prelocked_mode && !is_bulk_insert_mode)
-  {
+      !thd->prelocked_mode)
     table->file->start_bulk_insert((ha_rows) 0);
-    is_bulk_insert_mode= TRUE;
-  }
   DBUG_RETURN(0);
 }
 
@@ -2941,7 +2937,6 @@ bool select_insert::send_eof()
   DBUG_ENTER("select_insert::send_eof");
 
   error= (!thd->prelocked_mode) ? table->file->end_bulk_insert():0;
-  is_bulk_insert_mode= FALSE;
   table->file->extra(HA_EXTRA_NO_IGNORE_DUP_KEY);
   table->file->extra(HA_EXTRA_WRITE_CANNOT_REPLACE);
 
@@ -3277,10 +3272,7 @@ select_create::prepare(List<Item> &values, SELECT_LEX_UNIT *u)
   if (info.handle_duplicates == DUP_UPDATE)
     table->file->extra(HA_EXTRA_INSERT_WITH_UPDATE);
   if (!thd->prelocked_mode)
-  {
     table->file->start_bulk_insert((ha_rows) 0);
-    is_bulk_insert_mode= TRUE;
-  }
   thd->abort_on_warning= (!info.ignore &&
                           (thd->variables.sql_mode &
                            (MODE_STRICT_TRANS_TABLES |