Method ha_check_overlaps

sql/handler.cc:8292–8398

int handler::ha_check_overlaps(const uchar *old_data, const uchar* new_data)
{
  DBUG_ASSERT(new_data);
  DBUG_ASSERT(this == table->file);
  if (!table_share->period.unique_keys)
    return 0;
  if (table->versioned())
  {
    Field *end= table->vers_end_field();
    if (!end->is_max(end->ptr_in_record(new_data)))
      return 0;
  }

  const bool after_write= ha_table_flags() & HA_CHECK_UNIQUE_AFTER_WRITE;
  const bool is_update= !after_write && old_data;
  uchar *record_buffer= lookup_buffer + table_share->max_unique_length
                                      + table_share->null_fields;

  // Needed to compare record refs later
  if (is_update)
    position(old_data);

  DBUG_ASSERT(!keyread_enabled());

  int error= 0;
  lookup_errkey= (uint)-1;

  for (uint key_nr= 0; key_nr < table_share->keys && !error; key_nr++)
  {
    const KEY &key_info= table->key_info[key_nr];
    const uint key_parts= key_info.user_defined_key_parts;
    if (!key_info.without_overlaps)
      continue;

    if (is_update)
    {
      bool key_used= false;
      for (uint k= 0; k < key_parts && !key_used; k++)
        key_used= bitmap_is_set(table->write_set,
                                key_info.key_part[k].fieldnr - 1);
      if (!key_used)
        continue;
    }

    error= lookup_handler->ha_index_init(key_nr, 0);
    if (error)
      return error;

    error= lookup_handler->ha_start_keyread(key_nr);
    DBUG_ASSERT(!error);

    const uint period_field_length= key_info.key_part[key_parts - 1].length;
    const uint key_base_length= key_info.key_length - 2 * period_field_length;

    key_copy(lookup_buffer, new_data, &key_info, 0);

    /* Copy period_start to period_end.
       the value in period_start field is not significant, but anyway let's leave