Commit 3c814f22 authored by igor@olga.mysql.com's avatar igor@olga.mysql.com
Browse files

Fixed bug #25219: crash for a query that contains an EXIST subquery with 

UNION over correlated and uncorrelated SELECTS.
In such subqueries each uncorrelated SELECT should be considered as
uncacheable. Otherwise join_free is called for it and in many cases
it causes some problems.
parent 0d665bd5

mysql-test/r/subselect.result

+33 −0
Original line number Diff line number Diff line
@@ -3605,3 +3605,36 @@ FROM t1) t; 
COUNT(*)

3000

DROP TABLE t1,t2;

CREATE TABLE t1 (id char(4) PRIMARY KEY, c int);

CREATE TABLE t2 (c int);

INSERT INTO t1 VALUES ('aa', 1);

INSERT INTO t2 VALUES (1);

SELECT * FROM t1 

WHERE EXISTS (SELECT c FROM t2 WHERE c=1

UNION 

SELECT c from t2 WHERE c=t1.c);

id	c

aa	1

INSERT INTO t1 VALUES ('bb', 2), ('cc', 3), ('dd',1);

SELECT * FROM t1 

WHERE EXISTS (SELECT c FROM t2 WHERE c=1

UNION 

SELECT c from t2 WHERE c=t1.c);

id	c

aa	1

bb	2

cc	3

dd	1

INSERT INTO t2 VALUES (2);

CREATE TABLE t3 (c int);

INSERT INTO t3 VALUES (1);

SELECT * FROM t1 

WHERE EXISTS (SELECT t2.c FROM t2 JOIN t3 ON t2.c=t3.c WHERE t2.c=1

UNION 

SELECT c from t2 WHERE c=t1.c);

id	c

aa	1

bb	2

cc	3

dd	1

DROP TABLE t1,t2,t3;

mysql-test/t/subselect.test

+34 −0
Original line number Diff line number Diff line
@@ -2508,3 +2508,37 @@ SELECT SQL_NO_CACHE COUNT(*) 
          FROM t1) t;



DROP TABLE t1,t2;



#

# Bug #25219: EXIST subquery with UNION over a mix of

#             correlated and uncorrelated selects

#             



CREATE TABLE t1 (id char(4) PRIMARY KEY, c int);

CREATE TABLE t2 (c int);



INSERT INTO t1 VALUES ('aa', 1);

INSERT INTO t2 VALUES (1);



SELECT * FROM t1 

  WHERE EXISTS (SELECT c FROM t2 WHERE c=1

                UNION 

                SELECT c from t2 WHERE c=t1.c);



INSERT INTO t1 VALUES ('bb', 2), ('cc', 3), ('dd',1);



SELECT * FROM t1 

  WHERE EXISTS (SELECT c FROM t2 WHERE c=1

                UNION 

                SELECT c from t2 WHERE c=t1.c);



INSERT INTO t2 VALUES (2);

CREATE TABLE t3 (c int);

INSERT INTO t3 VALUES (1);



SELECT * FROM t1 

  WHERE EXISTS (SELECT t2.c FROM t2 JOIN t3 ON t2.c=t3.c WHERE t2.c=1

                UNION 

                SELECT c from t2 WHERE c=t1.c);



DROP TABLE t1,t2,t3;

sql/mysql_priv.h

+4 −1
Original line number Diff line number Diff line
@@ -410,7 +410,10 @@ MY_LOCALE *my_locale_by_name(const char *name); 
#define UNCACHEABLE_EXPLAIN     8

/* Don't evaluate subqueries in prepare even if they're not correlated */

#define UNCACHEABLE_PREPARE    16

/* Used to chack GROUP BY list in the MODE_ONLY_FULL_GROUP_BY mode */

/* For uncorrelated SELECT in an UNION with some correlated SELECTs */

#define UNCACHEABLE_UNITED     32



/* Used to check GROUP BY list in the MODE_ONLY_FULL_GROUP_BY mode */

#define UNDEF_POS (-1)

#ifdef EXTRA_DEBUG

/*

sql/sql_lex.cc

+10 −2
Original line number Diff line number Diff line
@@ -1371,9 +1371,17 @@ void st_select_lex::mark_as_dependent(SELECT_LEX *last) 
    if (!(s->uncacheable & UNCACHEABLE_DEPENDENT))

    {

      // Select is dependent of outer select

      s->uncacheable|= UNCACHEABLE_DEPENDENT;

      s->uncacheable= (s->uncacheable & ~UNCACHEABLE_UNITED) |

                       UNCACHEABLE_DEPENDENT;

      SELECT_LEX_UNIT *munit= s->master_unit();

      munit->uncacheable|= UNCACHEABLE_DEPENDENT;

      munit->uncacheable= (munit->uncacheable & ~UNCACHEABLE_UNITED) |

                       UNCACHEABLE_DEPENDENT;

      for (SELECT_LEX *sl= munit->first_select(); sl ; sl= sl->next_select())

      {

        if (sl != s &&

            !(sl->uncacheable & (UNCACHEABLE_DEPENDENT | UNCACHEABLE_UNITED)))

          sl->uncacheable|= UNCACHEABLE_UNITED;

      }

    }

  is_correlated= TRUE;

  this->master_unit()->item->is_correlated= TRUE;