Function init_key_info

sql/sql_table.cc:3101–3161

@brief Initialize the key length and algorithm (if long hash). This function does: 1. Append system key parts (versioning, periods) 2. Call Type_handler key_part initialization function. 3. Determine the length of each key_part. 4. Calculate the total Key length. 5. Determine if the key is long unique based on its length smd result from type handler. It'll be saved in key_cr

  @return   TRUE    error
 */
static
my_bool init_key_info(THD *thd, Alter_info *alter_info,
                      HA_CREATE_INFO *create_info,
                      const handler *file)
{
  DBUG_ENTER("init_key_info");
  uint max_key_length= file->max_key_length();
  uint max_key_part_length= file->max_key_part_length();

  for (Key &key: alter_info->key_list)
  {
    /*
      Ensure we aren't re-initializing keys that were already initialized.
    */
    DBUG_ASSERT(!key.length);

    if (key.type == Key::FOREIGN_KEY)
      continue;

    int parts_added= append_system_key_parts(thd, create_info, &key);
    if (parts_added < 0)
      DBUG_RETURN(true);

    bool is_hash_field_needed= false;
    for (Key_part_spec &kp: key.columns)
    {
      if (init_key_part_spec(thd, alter_info, file, key, kp,
                             max_key_length, max_key_part_length,
                             &is_hash_field_needed))
        DBUG_RETURN(TRUE);

      key.length+= kp.length;
      if (key.length > max_key_length)
      {
        if (key.type == Key::UNIQUE)
          is_hash_field_needed= true;  // for case "a BLOB UNIQUE"
        else if (key.type <= Key::MULTIPLE)
        {
          my_error(ER_TOO_LONG_KEY, MYF(0), max_key_length);
          DBUG_RETURN(TRUE);
        }
      }

      KEY_CREATE_INFO *key_cinfo= &key.key_create_info;

      if (is_hash_field_needed)
      {
        if (key_cinfo->algorithm == HA_KEY_ALG_UNDEF)
          key_cinfo->algorithm= HA_KEY_ALG_LONG_HASH;

        if (key_cinfo->algorithm != HA_KEY_ALG_HASH &&
            key_cinfo->algorithm != HA_KEY_ALG_LONG_HASH)
        {
          my_error(ER_TOO_LONG_KEY, MYF(0), max_key_length);
          DBUG_RETURN(TRUE);
        }
      }
    }