A fix and a test case for Bug#13488 "Left outer join query incorrectly

gives MYSQL_DATA_TRUNCATED"


sql/sql_cursor.cc:
  A partial fix for Bug#13488 "Left outer join query incorrectly gives 
  MYSQL_DATA_TRUNCATED": send the correct metadata of the cursor
  result set at execute. The full fix would be to make sure that
  the metadata doesn't change between prepare and execute.
tests/mysql_client_test.c:
  A test case for Bug#13488 "Left outer join query incorrectly gives 
  MYSQL_DATA_TRUNCATED"

sql/sql_cursor.cc

@@ -558,6 +558,24 @@ int Materialized_cursor::open(JOIN *join __attribute__((unused)))
        result->prepare(item_list, &fake_unit) ||
        table->file->ha_rnd_init(TRUE));
   thd->restore_active_arena(this, &backup_arena);
+  if (rc == 0)
+  {
+    /*
+      Now send the result set metadata to the client. We need to do it
+      here, as in Select_materialize::send_fields the exact column types
+      are not yet known. The new types may differ from the original ones
+      sent at prepare if some of them were altered by MySQL HEAP tables
+      mechanism -- used when create_tmp_field_from_item may alter the
+      original column type.
+
+      We can't simply supply SEND_EOF flag to send_fields, because
+      send_fields doesn't flush the network buffer.
+    */
+    rc= result->send_fields(item_list, Protocol::SEND_NUM_ROWS);
+    thd->server_status|= SERVER_STATUS_CURSOR_EXISTS;
+    result->send_eof();
+    thd->server_status&= ~SERVER_STATUS_CURSOR_EXISTS;
+  }
   return rc;
 }
 
@@ -647,14 +665,6 @@ bool Select_materialize::send_fields(List<Item> &list, uint flags)
   if (create_result_table(unit->thd, unit->get_unit_column_types(),
                           FALSE, thd->options | TMP_TABLE_ALL_COLUMNS, ""))
     return TRUE;
-  /*
-    We can't simply supply SEND_EOF flag to send_fields, because send_fields
-    doesn't flush the network buffer.
-  */
-  rc= result->send_fields(list, Protocol::SEND_NUM_ROWS);
-  thd->server_status|= SERVER_STATUS_CURSOR_EXISTS;
-  result->send_eof();
-  thd->server_status&= ~SERVER_STATUS_CURSOR_EXISTS;
   return rc;
 }
 

tests/mysql_client_test.c

@@ -14419,6 +14419,74 @@ static void test_bug14210()
   myquery(rc);
 }
 
+/* Bug#13488 */
+
+static void test_bug13488()
+{
+  MYSQL_BIND bind[3];
+  MYSQL_STMT *stmt1;
+  int rc, f1, f2, f3, i;
+  const ulong type= CURSOR_TYPE_READ_ONLY;
+  const char *query= "select * from t1 left join t2 on f1=f2 where f1=1";
+
+  myheader("test_bug13488");
+
+  rc= mysql_query(mysql, "drop table if exists t1, t2");
+  myquery(rc);
+  rc= mysql_query(mysql, "create table t1 (f1 int not null primary key)");
+  myquery(rc);
+  rc= mysql_query(mysql, "create table t2 (f2 int not null primary key, "
+                  "f3 int not null)");
+  myquery(rc);
+  rc= mysql_query(mysql, "insert into t1 values (1), (2)");
+  myquery(rc);
+  rc= mysql_query(mysql, "insert into t2 values (1,2), (2,4)");
+  myquery(rc);
+
+  memset(bind, 0, sizeof(bind));
+  for (i= 0; i < 3; i++)
+  {
+    bind[i].buffer_type= MYSQL_TYPE_LONG;
+    bind[i].buffer_length= 4;
+    bind[i].length= 0;
+  }
+  bind[0].buffer=&f1;
+  bind[1].buffer=&f2;
+  bind[2].buffer=&f3;
+
+  stmt1= mysql_stmt_init(mysql);
+  rc= mysql_stmt_attr_set(stmt1,STMT_ATTR_CURSOR_TYPE, (const void *)&type);
+  check_execute(stmt1, rc);
+
+  rc= mysql_stmt_prepare(stmt1, query, strlen(query));
+  check_execute(stmt1, rc);
+
+  rc= mysql_stmt_execute(stmt1);
+  check_execute(stmt1, rc);
+
+  rc= mysql_stmt_bind_result(stmt1, bind);
+  check_execute(stmt1, rc);
+
+  rc= mysql_stmt_fetch(stmt1);
+  check_execute(stmt1, rc);
+
+  rc= mysql_stmt_free_result(stmt1);
+  check_execute(stmt1, rc);
+
+  rc= mysql_stmt_reset(stmt1);
+  check_execute(stmt1, rc);
+
+  rc= mysql_stmt_close(stmt1);
+  check_execute(stmt1, rc);
+
+  if (!opt_silent)
+    printf("data is: %s", (f1 == 1 && f2 == 1 && f3 == 2)?"OK":
+           "wrong");
+  DIE_UNLESS(f1 == 1 && f2 == 1 && f3 == 2);
+  rc= mysql_query(mysql, "drop table t1, t2");
+  myquery(rc);
+}
+
 /*
   Read and parse arguments and MySQL options from my.cnf
 */
@@ -14675,6 +14743,7 @@ static struct my_tests_st my_tests[]= {
   { "test_bug11904", test_bug11904 },
   { "test_bug12243", test_bug12243 },
   { "test_bug14210", test_bug14210 },
+  { "test_bug13488", test_bug13488 },
   { 0, 0 }
 };