Commit fbebb47e authored by igor@olga.mysql.com's avatar igor@olga.mysql.com
Browse files

Fixed bug #28571. Outer join queries with ON conditions over 

constant outer tables did not return null complemented
rows when conditions were evaluated to FALSE.
Wrong results were returned because the conditions over constant
outer tables, when being pushed down, were erroneously enclosed 
into the guard function used for WHERE conditions.
parent dc32ee53

mysql-test/r/join_outer.result

+15 −0
Original line number Diff line number Diff line
@@ -1239,3 +1239,18 @@ Handler_read_prev 0 
Handler_read_rnd	0

Handler_read_rnd_next	6

DROP TABLE t1,t2;

CREATE TABLE t1 (c int  PRIMARY KEY, e int NOT NULL);

INSERT INTO t1 VALUES (1,0), (2,1);

CREATE TABLE t2 (d int PRIMARY KEY);

INSERT INTO t2 VALUES (1), (2), (3);

EXPLAIN SELECT * FROM t1 LEFT JOIN t2 ON e<>0 WHERE c=1 AND d IS NULL;

id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra

1	SIMPLE	t1	const	PRIMARY	PRIMARY	4	const	1	

1	SIMPLE	t2	index	NULL	PRIMARY	4	NULL	3	Using where; Using index; Not exists

SELECT * FROM t1 LEFT JOIN t2 ON e<>0 WHERE c=1 AND d IS NULL;

c	e	d

1	0	NULL

SELECT * FROM t1 LEFT JOIN t2 ON e<>0 WHERE c=1 AND d<=>NULL;

c	e	d

1	0	NULL

DROP TABLE t1,t2;

mysql-test/t/join_outer.test

+16 −0
Original line number Diff line number Diff line
@@ -845,3 +845,19 @@ SELECT t1.id, a FROM t1 LEFT JOIN t2 ON t1.id=t2.id WHERE t2.b IS NULL; 
show status like 'Handler_read%';



DROP TABLE t1,t2;



#

# Bug 28571: outer join with false on condition over constant tables 

#



CREATE TABLE t1 (c int  PRIMARY KEY, e int NOT NULL);

INSERT INTO t1 VALUES (1,0), (2,1);

CREATE TABLE t2 (d int PRIMARY KEY);

INSERT INTO t2 VALUES (1), (2), (3);



EXPLAIN SELECT * FROM t1 LEFT JOIN t2 ON e<>0 WHERE c=1 AND d IS NULL;

SELECT * FROM t1 LEFT JOIN t2 ON e<>0 WHERE c=1 AND d IS NULL;

SELECT * FROM t1 LEFT JOIN t2 ON e<>0 WHERE c=1 AND d<=>NULL;



DROP TABLE t1,t2;

sql/sql_select.cc

+29 −25
Original line number Diff line number Diff line
@@ -5666,28 +5666,6 @@ make_join_select(JOIN *join,SQL_SELECT *select,COND *cond) 
                              join->const_table_map,

                              (table_map) 0);

        DBUG_EXECUTE("where",print_where(const_cond,"constants"););

        for (JOIN_TAB *tab= join->join_tab+join->const_tables;

             tab < join->join_tab+join->tables ; tab++)

        {

          if (*tab->on_expr_ref)

          {

            JOIN_TAB *cond_tab= tab->first_inner;

            COND *tmp= make_cond_for_table(*tab->on_expr_ref,

                                           join->const_table_map,

                                         (  table_map) 0);

            if (!tmp)

              continue;

            tmp= new Item_func_trig_cond(tmp, &cond_tab->not_null_compl);

            if (!tmp)

              DBUG_RETURN(1);

            tmp->quick_fix_field();

            cond_tab->select_cond= !cond_tab->select_cond ? tmp :

	                            new Item_cond_and(cond_tab->select_cond,tmp);

            if (!cond_tab->select_cond)

	      DBUG_RETURN(1);

            cond_tab->select_cond->quick_fix_field();

          }       

        }

        if (const_cond && !const_cond->val_int())

        {

	  DBUG_PRINT("info",("Found impossible WHERE condition"));
@@ -5918,13 +5896,39 @@ make_join_select(JOIN *join,SQL_SELECT *select,COND *cond) 
      }

      

      /* 

        Push down all predicates from on expressions.

        Each of these predicated are guarded by a variable

        Push down conditions from all on expressions.

        Each of these conditions are guarded by a variable

        that turns if off just before null complemented row for

        outer joins is formed. Thus, the predicates from an

        outer joins is formed. Thus, the condition from an

        'on expression' are guaranteed not to be checked for

        the null complemented row.

      */ 



      /* First push down constant conditions from on expressions */

      for (JOIN_TAB *tab= join->join_tab+join->const_tables;

           tab < join->join_tab+join->tables ; tab++)

      {

        if (*tab->on_expr_ref)

        {

          JOIN_TAB *cond_tab= tab->first_inner;

          COND *tmp= make_cond_for_table(*tab->on_expr_ref,

                                         join->const_table_map,

                                         (table_map) 0);

          if (!tmp)

            continue;

          tmp= new Item_func_trig_cond(tmp, &cond_tab->not_null_compl);

          if (!tmp)

            DBUG_RETURN(1);

          tmp->quick_fix_field();

          cond_tab->select_cond= !cond_tab->select_cond ? tmp :

	                            new Item_cond_and(cond_tab->select_cond,tmp);

          if (!cond_tab->select_cond)

	    DBUG_RETURN(1);

          cond_tab->select_cond->quick_fix_field();

        }       

      }



      /* Push down non-constant conditions from on expressions */

      JOIN_TAB *last_tab= tab;

      while (first_inner_tab && first_inner_tab->last_inner == last_tab)

      {