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MDEV-25080 Fix crash for CREATE TABLE from pushed union

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During st_select_lex_unit::prepare() the member select_unit*
st_select_lex_unit::union_result is being assigned to an instance
of one of the following classes:
 - select_unit
 - select_unit_ext
 - select_unit_recursive
 - select_union_direct
Select_union_direct used to pass the result of the query directly to
the receiving select_result without filling a temporary table. This class
wraps a select_result object and is currently used to process UNION ALL
queries. Other select_unit_* classes involve some additional result processing.
Pushed down units are processed on the engine side so the results must be
also passed directly to a select_result object. So in the case when
the unit pushdown is employed st_select_lex_unit::union_result must be
assigned to an instance of select_union_direct.
This commit is contained in:
Oleg Smirnov
2023-02-04 14:12:54 +07:00
committed by Sergei Golubchik
parent 3118132228
commit b5507c738f
4 changed files with 142 additions and 29 deletions
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61
mysql-test/suite/federated/federatedx_create_handlers.result
View File

@ -555,14 +555,36 @@ WHERE id=2) dt2) dt
a b a b id name
1 1 NULL NULL NULL NULL
2 2 NULL NULL NULL NULL
DROP TABLES federated.t1, federated.t2, federated.t3, federated.t10,
federated.t11;
connection slave;
DROP TABLES federated.t1, federated.t2, federated.t3, federated.t10,
federated.t11;
# MDEV-25080: Allow pushdown of queries involving UNIONs
# in outer select to foreign engines
#
connection master;
TRUNCATE TABLE federated.t1;
TRUNCATE TABLE federated.t2;
connection slave;
CREATE TABLE federated.t1 (
a varchar(10)
)
DEFAULT CHARSET=latin1;
CREATE TABLE federated.t2 (
a varchar(16) NOT NULL default ''
)
DEFAULT CHARSET=latin1;
INSERT INTO federated.t1 VALUES ('abc'), ('bcd'), ('cde');
INSERT INTO federated.t2 VALUES ('abc'), ('bcd'), ('cde'), ('def'), ('efg');
connection master;
CREATE TABLE federated.t1 (
a varchar(10)
)
ENGINE="FEDERATED" DEFAULT CHARSET=latin1
CONNECTION='mysql://root@127.0.0.1:SLAVE_PORT/federated/t1';
CREATE TABLE federated.t2 (
a varchar(16) NOT NULL default ''
)
ENGINE="FEDERATED" DEFAULT CHARSET=latin1
CONNECTION='mysql://root@127.0.0.1:SLAVE_PORT/federated/t2';
CREATE TABLE t3 (a varchar(30)) ENGINE=MyISAM;
CREATE TABLE t4 (a varchar(30)) ENGINE=MyISAM;
INSERT INTO t3 VALUES ('t3_myisam1'), ('t3_myisam2'), ('t3_myisam3');
@ -1033,9 +1055,38 @@ common
123456789000
t14abcde
t14xyzzz
# CREATE TABLE .. AS from a pushed UNION
CREATE TABLE t5 AS SELECT * FROM federated.t13 UNION
SELECT * FROM federated.t14;
SHOW CREATE TABLE t5;
Table Create Table
t5 CREATE TABLE `t5` (
`a` varchar(8) DEFAULT NULL
) ENGINE=MyISAM DEFAULT CHARSET=latin1 COLLATE=latin1_swedish_ci
SELECT * FROM t5;
a
common
t13abc
t13xx
t14abcde
t14xyzzz
CREATE TABLE t6 AS SELECT a FROM federated.t12 EXCEPT
SELECT 1 UNION ALL
SELECT a FROM federated.t11 EXCEPT
SELECT 0;
SHOW CREATE TABLE t6;
Table Create Table
t6 CREATE TABLE `t6` (
`a` decimal(10,0) NOT NULL DEFAULT 0
) ENGINE=MyISAM DEFAULT CHARSET=latin1 COLLATE=latin1_swedish_ci
SELECT * FROM t6;
a
-1
-32678
32767
connection master;
DROP TABLES federated.t1, federated.t2, t3, t4, federated.t11, federated.t12,
federated.t13, federated.t14;
DROP TABLES federated.t1, federated.t2, t3, t4, t5, t6, federated.t11,
federated.t12, federated.t13, federated.t14;
connection slave;
DROP TABLES federated.t1, federated.t2, federated.t11, federated.t12,
federated.t13, federated.t14;

59
mysql-test/suite/federated/federatedx_create_handlers.test
View File

@ -375,18 +375,49 @@ SELECT * FROM t10 LEFT JOIN
WHERE id=2) dt2) dt
) ON t10.a=t11.a;
DROP TABLES federated.t1, federated.t2, federated.t3, federated.t10,
federated.t11;
connection slave;
DROP TABLES federated.t1, federated.t2, federated.t3, federated.t10,
federated.t11;
--echo # MDEV-25080: Allow pushdown of queries involving UNIONs
--echo # in outer select to foreign engines
--echo #
connection master;
connection slave;
TRUNCATE TABLE federated.t1;
TRUNCATE TABLE federated.t2;
CREATE TABLE federated.t1 (
a varchar(10)
)
DEFAULT CHARSET=latin1;
CREATE TABLE federated.t2 (
a varchar(16) NOT NULL default ''
)
DEFAULT CHARSET=latin1;
INSERT INTO federated.t1 VALUES ('abc'), ('bcd'), ('cde');
INSERT INTO federated.t2 VALUES ('abc'), ('bcd'), ('cde'), ('def'), ('efg');
connection master;
--replace_result $SLAVE_MYPORT SLAVE_PORT
eval
CREATE TABLE federated.t1 (
a varchar(10)
)
ENGINE="FEDERATED" DEFAULT CHARSET=latin1
CONNECTION='mysql://root@127.0.0.1:$SLAVE_MYPORT/federated/t1';
--replace_result $SLAVE_MYPORT SLAVE_PORT
eval
CREATE TABLE federated.t2 (
a varchar(16) NOT NULL default ''
)
ENGINE="FEDERATED" DEFAULT CHARSET=latin1
CONNECTION='mysql://root@127.0.0.1:$SLAVE_MYPORT/federated/t2';
CREATE TABLE t3 (a varchar(30)) ENGINE=MyISAM;
CREATE TABLE t4 (a varchar(30)) ENGINE=MyISAM;
@ -467,7 +498,6 @@ EXPLAIN
--echo # at the server side
--disable_warnings
SELECT count(*) FROM federated.t1 UNION
SELECT count(*) FROM federated.t1 EXCEPT
SELECT count(*)+1 FROM federated.t1
@ -482,7 +512,6 @@ EXPLAIN FORMAT=JSON SELECT count(*) FROM federated.t1 UNION
SELECT count(*) FROM federated.t2 EXCEPT
SELECT count(*)+2 FROM federated.t2
INTO @var;
--enable_warnings
--echo # Prepared statements
@ -549,6 +578,7 @@ EXPLAIN (SELECT * FROM federated.t1 UNION SELECT * FROM federated.t2)
--echo # Union of tables containing different INT data types
connection slave;
CREATE TABLE federated.t11 (a smallint(6) NOT NULL);
INSERT INTO federated.t11 VALUES (-32678), (-1), (0);
@ -625,10 +655,25 @@ SELECT * FROM federated.t13 UNION
SELECT '123456789000' UNION
SELECT * FROM federated.t14;
--echo # CREATE TABLE .. AS from a pushed UNION
CREATE TABLE t5 AS SELECT * FROM federated.t13 UNION
SELECT * FROM federated.t14;
SHOW CREATE TABLE t5;
--sorted_result
SELECT * FROM t5;
CREATE TABLE t6 AS SELECT a FROM federated.t12 EXCEPT
SELECT 1 UNION ALL
SELECT a FROM federated.t11 EXCEPT
SELECT 0;
SHOW CREATE TABLE t6;
--sorted_result
SELECT * FROM t6;
# Cleanup
connection master;
DROP TABLES federated.t1, federated.t2, t3, t4, federated.t11, federated.t12,
federated.t13, federated.t14;
DROP TABLES federated.t1, federated.t2, t3, t4, t5, t6, federated.t11,
federated.t12, federated.t13, federated.t14;
connection slave;
DROP TABLES federated.t1, federated.t2, federated.t11, federated.t12,

1
sql/sql_lex.h
View File

@ -1056,6 +1056,7 @@ public:
private:
bool exec_inner();
bool is_derived_eliminated() const;
bool set_direct_union_result(select_result *sel_result);
};
typedef class st_select_lex_unit SELECT_LEX_UNIT;

50
sql/sql_union.cc
View File

@ -1388,6 +1388,7 @@ bool st_select_lex_unit::prepare(TABLE_LIST *derived_arg,
bool have_except= false, have_intersect= false,
have_except_all_or_intersect_all= false;
bool instantiate_tmp_table= false;
bool use_direct_union_result= false;
bool single_tvc= !first_sl->next_select() && first_sl->tvc;
bool single_tvc_wo_order= single_tvc && !first_sl->order_list.elements;
bool distinct_key= 0;
@ -1511,23 +1512,18 @@ bool st_select_lex_unit::prepare(TABLE_LIST *derived_arg,
}
}
/* Global option */
if (is_union_select || is_recursive)
{
if ((single_tvc_wo_order && !fake_select_lex) ||
(is_unit_op() && !union_needs_tmp_table() &&
!have_except && !have_intersect && !single_tvc))
!have_except && !have_intersect && !single_tvc))
{
SELECT_LEX *last= first_select();
while (last->next_select())
last= last->next_select();
if (!(tmp_result= union_result=
new (thd->mem_root) select_union_direct(thd, sel_result,
last)))
goto err; /* purecov: inspected */
if (unlikely(set_direct_union_result(sel_result)))
goto err;
tmp_result= union_result;
fake_select_lex= NULL;
instantiate_tmp_table= false;
use_direct_union_result= true;
}
else
{
@ -1763,6 +1759,24 @@ bool st_select_lex_unit::prepare(TABLE_LIST *derived_arg,
goto err;
cont:
pushdown_unit= find_unit_handler(thd, this);
if (pushdown_unit)
{
if (unlikely(pushdown_unit->prepare()))
goto err;
/*
Always use select_union_direct result for pushed down units, overwrite
the previous union_result unless select_union_direct is already used
*/
if (!use_direct_union_result)
{
if (unlikely(set_direct_union_result(sel_result)))
goto err;
fake_select_lex= NULL;
instantiate_tmp_table= false;
use_direct_union_result= true;
}
}
/*
If the query is using select_union_direct, we have postponed
preparation of the underlying select_result until column types
@ -1965,13 +1979,6 @@ cont:
}
}
pushdown_unit= find_unit_handler(thd, this);
if (pushdown_unit)
{
if (unlikely(pushdown_unit->prepare()))
DBUG_RETURN(TRUE);
}
thd->lex->current_select= lex_select_save;
DBUG_RETURN(saved_error || thd->is_fatal_error);
@ -1982,6 +1989,15 @@ err:
DBUG_RETURN(TRUE);
}
bool st_select_lex_unit::set_direct_union_result(select_result *sel_result)
{
SELECT_LEX *last= first_select();
while (last->next_select())
last= last->next_select();
union_result= new (thd->mem_root) select_union_direct(thd, sel_result,
last);
return (union_result == nullptr);
}
/**
@brief