Commit 1fc04e0b authored by unknown's avatar unknown
Browse files

Fix for BUG#4480: In joins with SELECT_STRAIGHT_JOIN re-order tables by outer join dependency, 

so we read dependent tables after tables they depend on (this is needed for outer joins)


mysql-test/r/join_outer.result:
  Test for BUG#4480
mysql-test/t/join_outer.test:
  Test for BUG#4480
parent de5ce111

mysql-test/r/join_outer.result

+15 −0
Original line number Diff line number Diff line
@@ -853,4 +853,19 @@ id select_type table type possible_keys key key_len ref rows Extra 
1	SIMPLE	t1	const	PRIMARY	PRIMARY	4	const	1	Using index

1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	2	

1	SIMPLE	t3	ALL	NULL	NULL	NULL	NULL	2	

drop table t1,t2;

create table t1 (a int, b int);

insert into t1 values (1,1),(2,2),(3,3);

create table t2 (a int, b int);

insert into t2 values (1,1), (2,2);

select * from t2 right join t1 on t2.a=t1.a;

a	b	a	b

1	1	1	1

2	2	2	2

NULL	NULL	3	3

select straight_join * from t2 right join t1 on t2.a=t1.a;

a	b	a	b

1	1	1	1

2	2	2	2

NULL	NULL	3	3

DROP TABLE t0,t1,t2,t3;

mysql-test/t/join_outer.test

+10 −0
Original line number Diff line number Diff line
@@ -606,4 +606,14 @@ INSERT INTO t1 VALUES (0); 
SELECT * FROM t0, t1 LEFT JOIN (t2,t3) ON a1=5 WHERE a0=a1 AND a0=1;

EXPLAIN SELECT * FROM t0, t1 LEFT JOIN (t2,t3) ON a1=5 WHERE a0=a1 AND a0=1;



# Test for BUG#4480

drop table t1,t2;

create table t1 (a int, b int);

insert into t1 values (1,1),(2,2),(3,3);

create table t2 (a int, b int);

insert into t2 values (1,1), (2,2);



select * from t2 right join t1 on t2.a=t1.a;

select straight_join * from t2 right join t1 on t2.a=t1.a;



DROP TABLE t0,t1,t2,t3;

sql/sql_select.cc

+32 −10
Original line number Diff line number Diff line
@@ -64,6 +64,7 @@ static void best_extension_by_limited_search(JOIN *join, 
                                             uint prune_level);

static uint determine_search_depth(JOIN* join);

static int join_tab_cmp(const void* ptr1, const void* ptr2);

static int join_tab_cmp_straight(const void* ptr1, const void* ptr2);

/*

  TODO: 'find_best' is here only temporarily until 'greedy_search' is

  tested and approved.
@@ -3678,22 +3679,26 @@ choose_plan(JOIN *join, table_map join_tables) 
{

  uint search_depth= join->thd->variables.optimizer_search_depth;

  uint prune_level=  join->thd->variables.optimizer_prune_level;



  bool straight_join= join->select_options & SELECT_STRAIGHT_JOIN;

  DBUG_ENTER("choose_plan");



  if (join->select_options & SELECT_STRAIGHT_JOIN)

  {

    optimize_straight_join(join, join_tables);

  }

  else

  {

  /*

      Heuristic: pre-sort all access plans with respect to the number of

    if (SELECT_STRAIGHT_JOIN option is set)

      reorder tables so dependent tables come after tables they depend 

      on, otherwise keep tables in the order they were specified in the query 

    else

      Apply heuristic: pre-sort all access plans with respect to the number of

      records accessed.

  */

  qsort(join->best_ref + join->const_tables, join->tables - join->const_tables,

          sizeof(JOIN_TAB*), join_tab_cmp);

        sizeof(JOIN_TAB*), straight_join?join_tab_cmp_straight:join_tab_cmp);

  

  if (straight_join)

  {

    optimize_straight_join(join, join_tables);

  }

  else

  {

    if (search_depth == MAX_TABLES+2)

    { /*

        TODO: 'MAX_TABLES+2' denotes the old implementation of find_best before
@@ -3750,6 +3755,23 @@ join_tab_cmp(const void* ptr1, const void* ptr2) 
}





/* 

  Same as join_tab_cmp, but for use with SELECT_STRAIGHT_JOIN.

*/



static int

join_tab_cmp_straight(const void* ptr1, const void* ptr2)

{

  JOIN_TAB *jt1= *(JOIN_TAB**) ptr1;

  JOIN_TAB *jt2= *(JOIN_TAB**) ptr2;



  if (jt1->dependent & jt2->table->map)

    return 1;

  if (jt2->dependent & jt1->table->map)

    return -1;

  return jt1 > jt2 ? 1 : (jt1 < jt2 ? -1 : 0);

}



/*

  Heuristic procedure to automatically guess a reasonable degree of

  exhaustiveness for the greedy search procedure.