Function clear_tables

sql/sql_select.cc:17973–17993

*/

static void clear_tables(JOIN *join, table_map *cleared_tables)
{
  DBUG_ASSERT(cleared_tables);
  for (uint i= 0 ; i < join->table_count ; i++)
  {
    TABLE *table= join->table[i];

    if (table->null_row)
      continue;                                 // Nothing more to do
    (*cleared_tables)|= (((table_map) 1) << i);
    if (table->s->null_bytes)
    {
      /*
        Remember null bits for the record so that we can restore the
        original const record in unclear_tables()
      */
      memcpy(table->record[1], table->null_flags, table->s->null_bytes);
    }
    mark_as_null_row(table);                  // All fields are NULL
  }
}


/**