Commit 61c8b3a8 authored by unknown's avatar unknown
Browse files

Refactor parts of do_select() (JOIN execution). 


sql/sql_select.cc:
  Bits of refactoring of do_select as one step forward to merge cursor and
  non-cursor execution.
  Moving send_fields (metadata handling) out of do_select to one level up
  and moving end_select setting to a separate function.
  This function is used in the Cursor::open() too.
parent 7503894a

sql/sql_select.cc

+57 −36
Original line number Diff line number Diff line
@@ -111,6 +111,7 @@ static bool const_expression_in_where(COND *conds,Item *item, Item **comp_item); 
static bool open_tmp_table(TABLE *table);

static bool create_myisam_tmp_table(TABLE *table,TMP_TABLE_PARAM *param,

				    ulong options);

static Next_select_func setup_end_select_func(JOIN *join);

static int do_select(JOIN *join,List<Item> *fields,TABLE *tmp_table,

		     Procedure *proc);

static int sub_select_cache(JOIN *join,JOIN_TAB *join_tab,bool end_of_records);
@@ -1638,6 +1639,8 @@ JOIN::exec() 
  {

    thd->proc_info="Sending data";

    DBUG_PRINT("info", ("%s", thd->proc_info));

    result->send_fields(*curr_fields_list,

                        Protocol::SEND_NUM_ROWS | Protocol::SEND_EOF);

    error= do_select(curr_join, curr_fields_list, NULL, procedure);

    thd->limit_found_rows= curr_join->send_records;

    thd->examined_row_count= curr_join->examined_rows;
@@ -1776,12 +1779,7 @@ Cursor::open(JOIN *join_arg) 
  thd->server_status&= ~SERVER_STATUS_CURSOR_EXISTS;



  /* Prepare JOIN for reading rows. */



  Next_select_func end_select= join->sort_and_group || join->procedure &&

    join->procedure->flags & PROC_GROUP ?

    end_send_group : end_send;



  join->join_tab[join->tables-1].next_select= end_select;

  join->join_tab[join->tables-1].next_select= setup_end_select_func(join);

  join->send_records= 0;

  join->fetch_limit= join->unit->offset_limit_cnt;
@@ -1802,6 +1800,11 @@ Cursor::open(JOIN *join_arg) 
  */

  DBUG_ASSERT(join_tab->table->null_row == 0);



  /*

    There is always at least one record in the table, as otherwise we

    wouldn't have opened the cursor. Therefore a failure is the only

    reason read_first_record can return not 0.

  */

  DBUG_RETURN(join_tab->read_first_record(join_tab));

}
@@ -8733,36 +8736,24 @@ bool create_myisam_from_heap(THD *thd, TABLE *table, TMP_TABLE_PARAM *param, 
}





/****************************************************************************

  Make a join of all tables and write it on socket or to table

  Return:  0 if ok

           1 if error is sent

          -1 if error should be sent

****************************************************************************/

/*

  SYNOPSIS

    setup_end_select_func()

    join   join to setup the function for.



static int

do_select(JOIN *join,List<Item> *fields,TABLE *table,Procedure *procedure)

{

  int error= 0;

  JOIN_TAB *join_tab;

  Next_select_func end_select;

  DBUG_ENTER("do_select");

  DESCRIPTION

    Rows produced by a join sweep may end up in a temporary table or be sent

    to a client. Setup the function of the nested loop join algorithm which

    handles final fully constructed and matched records.



  join->procedure=procedure;

  /*

    Tell the client how many fields there are in a row

  RETURN

    end_select function to use. This function can't fail.

*/

  if (!table)

    join->result->send_fields(*fields,

                              Protocol::SEND_NUM_ROWS | Protocol::SEND_EOF);

  else

  {

    VOID(table->file->extra(HA_EXTRA_WRITE_CACHE));

    empty_record(table);

  }

  join->tmp_table= table;			/* Save for easy recursion */

  join->fields= fields;



static Next_select_func setup_end_select_func(JOIN *join)

{

  TABLE *table= join->tmp_table;

  Next_select_func end_select;

  /* Set up select_end */

  if (table)

  {
@@ -8772,8 +8763,6 @@ do_select(JOIN *join,List<Item> *fields,TABLE *table,Procedure *procedure) 
      {

	DBUG_PRINT("info",("Using end_update"));

	end_select=end_update;

        if (!table->file->inited)

          table->file->ha_index_init(0);

      }

      else

      {
@@ -8807,7 +8796,38 @@ do_select(JOIN *join,List<Item> *fields,TABLE *table,Procedure *procedure) 
    else

      end_select= end_send;

  }

  join->join_tab[join->tables-1].next_select=end_select;

  return end_select;

}





/****************************************************************************

  Make a join of all tables and write it on socket or to table

  Return:  0 if ok

           1 if error is sent

          -1 if error should be sent

****************************************************************************/



static int

do_select(JOIN *join,List<Item> *fields,TABLE *table,Procedure *procedure)

{

  int error= 0;

  JOIN_TAB *join_tab;

  DBUG_ENTER("do_select");



  join->procedure=procedure;

  join->tmp_table= table;			/* Save for easy recursion */

  join->fields= fields;



  if (table)

  {

    VOID(table->file->extra(HA_EXTRA_WRITE_CACHE));

    empty_record(table);

    if (table->group && join->tmp_table_param.sum_func_count &&

        table->s->keys && !table->file->inited)

      table->file->ha_index_init(0);

  }

  /* Set up select_end */

  join->join_tab[join->tables-1].next_select= setup_end_select_func(join);



  join_tab=join->join_tab+join->const_tables;

  join->send_records=0;
@@ -8819,6 +8839,7 @@ do_select(JOIN *join,List<Item> *fields,TABLE *table,Procedure *procedure) 
    */

    if (!join->conds || join->conds->val_int())

    {

      Next_select_func end_select= join->join_tab[join->tables-1].next_select;

      if (!(error=(*end_select)(join,join_tab,0)) || error == -3)

	error=(*end_select)(join,join_tab,1);

    }