Method join_matching_records

sql/sql_join_cache.cc:2320–2443

*/ 

enum_nested_loop_state JOIN_CACHE::join_matching_records(bool skip_last)
{
  int error;
  enum_nested_loop_state rc= NESTED_LOOP_OK;
  join_tab->table->null_row= 0;
  bool check_only_first_match= join_tab->check_only_first_match();
  DBUG_ENTER("JOIN_CACHE::join_matching_records");

  /* Return at once if there are no records in the join buffer */
  if (!records)     
    DBUG_RETURN(NESTED_LOOP_OK);
 
  /* 
    When joining we read records from the join buffer back into record buffers.
    If matches for the last partial join record are found through a call to
    the sub_select function then this partial join record must be saved in the
    join buffer in order to be restored just before the sub_select call.
  */             
  if (skip_last)     
    put_record();     
 
  if (join_tab->use_quick == 2 && join_tab->select->quick)
  { 
    /* A dynamic range access was used last. Clean up after it */
    delete join_tab->select->quick;
    join_tab->select->quick= 0;
  }

  if ((rc= join_tab_execution_startup(join_tab)) < 0)
    goto finish2;

  if (join_tab->need_to_build_rowid_filter && 
      join_tab->build_range_rowid_filter())
  {
    rc= NESTED_LOOP_ERROR;
    goto finish2;
  }

  /* Prepare to retrieve all records of the joined table */
  if (unlikely((error= join_tab_scan->open())))
  { 
    /* 
      TODO: if we get here, we will assert in net_send_statement(). Add test
      coverage and fix.
    */
    goto finish;
  }

  while (!(error= join_tab_scan->next()))   
  {
    if (unlikely(join->thd->check_killed()))
    {
      /* The user has aborted the execution of the query */
      rc= NESTED_LOOP_KILLED;
      goto finish; 
    }

    if (join_tab->keep_current_rowid)