Function evaluate_join_record

sql/sql_select.cc:24792–24989

*/

static enum_nested_loop_state
evaluate_join_record(JOIN *join, JOIN_TAB *join_tab,
                     int error)
{
  bool shortcut_for_distinct= join_tab->shortcut_for_distinct;
  ha_rows found_records=join->found_records;
  COND *select_cond= join_tab->select_cond;
  bool select_cond_result= TRUE;
  DBUG_ENTER("evaluate_join_record");
  DBUG_PRINT("enter",
             ("evaluate_join_record join: %p  join_tab: %p  "
              "cond: %p  abort: %d  alias %s",
              join, join_tab, select_cond, error,
              join_tab->table->alias.ptr()));

  if (error > 0 || unlikely(join->thd->is_error())) // Fatal error
    DBUG_RETURN(NESTED_LOOP_ERROR);
  if (error < 0)
    DBUG_RETURN(NESTED_LOOP_NO_MORE_ROWS);
  if (unlikely(join->thd->check_killed()))       // Aborted by user
  {
    DBUG_RETURN(NESTED_LOOP_KILLED);            /* purecov: inspected */
  }

  join_tab->tracker->r_rows++;

  if (select_cond)
  {
    select_cond_result= MY_TEST(select_cond->val_bool());

    /* check for errors evaluating the condition */
    if (unlikely(join->thd->is_error()))
      DBUG_RETURN(NESTED_LOOP_ERROR);
  }

  if (select_cond_result)
  {
    /*
      There is no select condition or the attached pushed down
      condition is true => a match is found.
    */
    join_tab->tracker->r_rows_after_where++;

    bool found= 1;
    while (join_tab->first_unmatched && found)
    {
      /*
        The while condition is always false if join_tab is not
        the last inner join table of an outer join operation.
      */
      JOIN_TAB *first_unmatched= join_tab->first_unmatched;
      /*
        Mark that a match for current outer table is found.
        This activates push down conditional predicates attached
        to the all inner tables of the outer join.
      */
      first_unmatched->found= 1;
      for (JOIN_TAB *tab= first_unmatched; tab <= join_tab; tab++)