Method check_match

sql/sql_join_cache.cc:2582–2626

*/ 

inline bool JOIN_CACHE::check_match(uchar *rec_ptr)
{
  /* Check whether pushdown conditions are satisfied */
  DBUG_ENTER("JOIN_CACHE:check_match");

  if (join_tab->select && join_tab->select->skip_record(join->thd) <= 0)
    DBUG_RETURN(FALSE);
  
  join_tab->jbuf_tracker->r_rows_after_where++;

  if (!join_tab->is_last_inner_table())
    DBUG_RETURN(TRUE);

  /* 
     This is the last inner table of an outer join,
     and maybe of other embedding outer joins, or
     this is the last inner table of a semi-join.
  */
  JOIN_TAB *first_inner= join_tab->get_first_inner_table();
  do
  {
    set_match_flag_if_none(first_inner, rec_ptr);
    if (first_inner->check_only_first_match() &&
        !join_tab->first_inner)
      DBUG_RETURN(TRUE);
    /* 
      This is the first match for the outer table row.
      The function set_match_flag_if_none has turned the flag
      first_inner->found on. The pushdown predicates for
      inner tables must be re-evaluated with this flag on.
      Note that, if first_inner is the first inner table 
      of a semi-join, but is not an inner table of an outer join
      such that 'not exists' optimization can  be applied to it, 
      the re-evaluation of the pushdown predicates is not needed.
    */      
    for (JOIN_TAB *tab= first_inner; tab <= join_tab; tab++)
    {
      if (tab->select && tab->select->skip_record(join->thd) <= 0)
        DBUG_RETURN(FALSE);
    }
  }
  while ((first_inner= first_inner->first_upper) &&
         first_inner->last_inner == join_tab);
    DBUG_RETURN(TRUE);
} 


/*