Function is_split_materialized_allowed

sql/opt_split.cc:337–356

 */

static bool is_split_materialized_allowed(THD *thd,
                                          const TABLE_LIST *derived,
                                          hint_state *hint)
{
  if (!derived)
  {
    *hint= hint_state::DISABLED;  // there is no derived table to hint on
    return false;
  }

  *hint= hint_table_state(thd,
                          derived,
                          SPLIT_MATERIALIZED_HINT_ENUM);

  const bool opt_flag= optimizer_flag(thd, OPTIMIZER_SWITCH_SPLIT_MATERIALIZED);
  const bool allow_split= (*hint == hint_state::ENABLED ||
                           (*hint == hint_state::NOT_PRESENT && opt_flag));

  return allow_split;
}


/* This structure is auxiliary and used only in the function that follows it */