set @tmp_jcl= @@join_cache_level;
set @tmp_opt= @@optimizer_switch;

CREATE TABLE t10(a INT);
INSERT INTO t10 VALUES (0),(1),(2),(3),(4),(5),(6),(7),(8),(9);
CREATE TABLE t12(a INT, b INT);
INSERT INTO t12 SELECT a,a from t10;
CREATE TABLE t13(a INT, b INT, c INT, filler CHAR(100), key (a,b));
INSERT INTO t13 select a,a,a, 'filler-data' FROM t10;

--echo
--echo ================================================================
set optimizer_switch= 'join_cache_hashed=on,join_cache_bka=on,mrr=on';

--echo
--echo ***********************************************
set join_cache_level = 0;
--source opt_hints_join_cache.inc

--echo
--echo ***********************************************
set join_cache_level = 1;
--source opt_hints_join_cache.inc

--echo
--echo ***********************************************
set join_cache_level = 2;
--source opt_hints_join_cache.inc

--echo
--echo ***********************************************
set join_cache_level = 3;
--source opt_hints_join_cache.inc

--echo
--echo ***********************************************
set join_cache_level = 4;
--source opt_hints_join_cache.inc

--echo
--echo ***********************************************
set join_cache_level = 5;
--source opt_hints_join_cache.inc

--echo
--echo ***********************************************
set join_cache_level = 6;
--source opt_hints_join_cache.inc

--echo
--echo ***********************************************
set join_cache_level = 7;
--source opt_hints_join_cache.inc

--echo
--echo ***********************************************
set join_cache_level = 8;
--source opt_hints_join_cache.inc

--echo
--echo ================================================================
set optimizer_switch= 'join_cache_hashed=off,join_cache_bka=on,mrr=on';

--echo
--echo ***********************************************
set join_cache_level = 0;
--source opt_hints_join_cache.inc

--echo
--echo ***********************************************
set join_cache_level = 1;
--source opt_hints_join_cache.inc

--echo
--echo ***********************************************
set join_cache_level = 2;
--source opt_hints_join_cache.inc

--echo
--echo ***********************************************
set join_cache_level = 3;
--source opt_hints_join_cache.inc

--echo
--echo ***********************************************
set join_cache_level = 4;
--source opt_hints_join_cache.inc

--echo
--echo ***********************************************
set join_cache_level = 5;
--source opt_hints_join_cache.inc

--echo
--echo ***********************************************
set join_cache_level = 6;
--source opt_hints_join_cache.inc

set join_cache_level = 7;
--source opt_hints_join_cache.inc

set join_cache_level = 8;
--source opt_hints_join_cache.inc

--echo
--echo ================================================================
set optimizer_switch= 'join_cache_hashed=on,join_cache_bka=off,mrr=on';

--echo
--echo ***********************************************
set join_cache_level = 0;
--source opt_hints_join_cache.inc

--echo
--echo ***********************************************
set join_cache_level = 1;
--source opt_hints_join_cache.inc

--echo
--echo ***********************************************
set join_cache_level = 2;
--source opt_hints_join_cache.inc

--echo
--echo ***********************************************
set join_cache_level = 3;
--source opt_hints_join_cache.inc

--echo
--echo ***********************************************
set join_cache_level = 4;
--source opt_hints_join_cache.inc

--echo
--echo ***********************************************
set join_cache_level = 5;
--source opt_hints_join_cache.inc

--echo
--echo ***********************************************
set join_cache_level = 6;
--source opt_hints_join_cache.inc

set join_cache_level = 7;
--source opt_hints_join_cache.inc

set join_cache_level = 8;
--source opt_hints_join_cache.inc

--echo
--echo ================================================================
set optimizer_switch= 'join_cache_hashed=off,join_cache_bka=off,mrr=on';

--echo
--echo ***********************************************
set join_cache_level = 0;
--source opt_hints_join_cache.inc

--echo
--echo ***********************************************
set join_cache_level = 1;
--source opt_hints_join_cache.inc

--echo
--echo ***********************************************
set join_cache_level = 2;
--source opt_hints_join_cache.inc

set join_cache_level = 3;
--source opt_hints_join_cache.inc

--echo
--echo ***********************************************
set join_cache_level = 4;
--source opt_hints_join_cache.inc

--echo
--echo ***********************************************
set join_cache_level = 5;
--source opt_hints_join_cache.inc

set join_cache_level = 6;
--source opt_hints_join_cache.inc

--echo
--echo ***********************************************
set join_cache_level = 7;
--source opt_hints_join_cache.inc

--echo
--echo ***********************************************
set join_cache_level = 8;
--source opt_hints_join_cache.inc

drop tables t10, t12, t13;

--echo
--echo ================================================================
set optimizer_switch= 'join_cache_hashed=on,join_cache_bka=on,mrr=on';

--echo #
--echo # BNL and NO_BNL hint testing
--echo #

set optimizer_switch=default;

CREATE TABLE t1 (a INT, b INT);
INSERT INTO t1 VALUES (1,1),(2,2);
CREATE TABLE t2 (a INT, b INT);
INSERT INTO t2 VALUES (1,1),(2,2);
CREATE TABLE t3 (a INT, b INT);
INSERT INTO t3 VALUES (1,1),(2,2);

--disable_ps2_protocol
--disable_cursor_protocol
--echo # Check statistics without hint
FLUSH STATUS;
SELECT t1.* FROM t1,t2,t3;
SHOW STATUS LIKE 'handler_read%';

--echo # Check statistics with hint
FLUSH STATUS;
SELECT /*+ NO_BNL() */t1.* FROM t1,t2,t3;
SHOW STATUS LIKE 'handler_read%';
--enable_ps2_protocol
--enable_cursor_protocol

EXPLAIN EXTENDED SELECT t1.* FROM t1,t2,t3;
EXPLAIN EXTENDED SELECT /*+ NO_BNL() */t1.* FROM t1,t2,t3;
EXPLAIN EXTENDED SELECT /*+ NO_BNL(t2, t3) */t1.* FROM t1,t2,t3;
EXPLAIN EXTENDED SELECT /*+ NO_BNL(t1, t3) */t1.* FROM t1,t2,t3;

--echo # Make sure query results are the same for any hints combination
--sorted_result
SELECT * FROM t1,t2,t3;
--sorted_result
SELECT /*+ BNL() */t1.* FROM t1,t2,t3;
--sorted_result
SELECT /*+ BNL(t1, t2) */t1.* FROM t1,t2,t3;
--sorted_result
SELECT /*+ BNL(t1, t3) */t1.* FROM t1,t2,t3;
--sorted_result
SELECT /*+ BNL(t2, t3) */t1.* FROM t1,t2,t3;
--sorted_result
SELECT /*+ BNL(t2) BNL(t3) */t1.* FROM t1,t2,t3;
--sorted_result
SELECT /*+ NO_BNL() */* FROM t1,t2,t3;
--sorted_result
SELECT /*+ NO_BNL(t1, t2) */* FROM t1,t2,t3;
--sorted_result
SELECT /*+ NO_BNL(t1, t3) */* FROM t1,t2,t3;
--sorted_result
SELECT /*+ NO_BNL(t2, t3) */* FROM t1,t2,t3;

--echo # BNL() overrides current join_cache_level setting
set join_cache_level = 0;
EXPLAIN EXTENDED SELECT t1.* FROM t1,t2,t3;
EXPLAIN EXTENDED SELECT /*+ BNL() */t1.* FROM t1,t2,t3;
EXPLAIN EXTENDED SELECT /*+ BNL(t1, t2) */t1.* FROM t1,t2,t3;
EXPLAIN EXTENDED SELECT /*+ BNL(t1, t3) */t1.* FROM t1,t2,t3;
EXPLAIN EXTENDED SELECT /*+ BNL(t2, t3) */t1.* FROM t1,t2,t3;
EXPLAIN EXTENDED SELECT /*+ BNL(t2) BNL(t3) */t1.* FROM t1,t2,t3;

DROP TABLE t1, t2, t3;
set join_cache_level = 8;

--echo # BNL in subquery
set optimizer_switch = DEFAULT;
CREATE TABLE t1 (a INT, b INT, PRIMARY KEY (a));
CREATE TABLE t2 (a INT);
CREATE TABLE t3 (a INT, b INT, INDEX a (a,b));
INSERT INTO t1 VALUES (1,10), (2,20), (3,30), (4,40);
INSERT INTO t2 VALUES (2), (3), (4), (5);
INSERT INTO t3 VALUES (10,3), (20,4), (30,5);
ANALYZE TABLE t1, t2, t3;

EXPLAIN EXTENDED SELECT /*+ QB_NAME(q) */ * FROM t1 JOIN t2 ON t1.a = t2.a WHERE
t2.a IN (SELECT /*+ QB_NAME(subq1) */ t3.b FROM t3 JOIN t1 t4 ON t3.a = t4.b);

EXPLAIN EXTENDED SELECT /*+ QB_NAME(q) NO_BNL() */ *
  FROM t1 JOIN t2 ON t1.a = t2.a
  WHERE t2.a IN (SELECT /*+ QB_NAME(subq1) */ t3.b FROM t3 JOIN t1 t4 ON t3.a = t4.b);

EXPLAIN EXTENDED SELECT /*+ QB_NAME(q) NO_BNL(t1, t2) */ *
  FROM t1 JOIN t2 ON t1.a = t2.a
  WHERE t2.a IN (SELECT /*+ QB_NAME(subq1) */ t3.b FROM t3 JOIN t1 t4 ON t3.a = t4.b);

EXPLAIN EXTENDED SELECT /*+ QB_NAME(q) NO_BNL(@subq1) */ *
  FROM t1 JOIN t2 ON t1.a = t2.a
  WHERE t2.a IN (SELECT /*+ QB_NAME(subq1) */ t3.b FROM t3 JOIN t1 t4 ON t3.a = t4.b);

EXPLAIN EXTENDED SELECT /*+ QB_NAME(q) NO_BNL(t4@subq1) */ *
  FROM t1 JOIN t2 ON t1.a = t2.a
  WHERE t2.a IN (SELECT /*+ QB_NAME(subq1) */ t3.b FROM t3 JOIN t1 t4 ON t3.a = t4.b);

EXPLAIN EXTENDED SELECT /*+ QB_NAME(q) NO_BNL(t3@subq1,t4@subq1) */ *
  FROM t1 JOIN t2 ON t1.a = t2.a
  WHERE t2.a IN (SELECT /*+ QB_NAME(subq1) */ t3.b FROM t3 JOIN t1 t4 ON t3.a = t4.b);

EXPLAIN EXTENDED SELECT /*+ QB_NAME(q) NO_BNL(@subq1 t3, t4) */ *
  FROM t1 JOIN t2 ON t1.a = t2.a
  WHERE t2.a IN (SELECT /*+ QB_NAME(subq1) */ t3.b FROM t3 JOIN t1 t4 ON t3.a = t4.b);

EXPLAIN EXTENDED SELECT /*+ QB_NAME(q) */ *
  FROM t1 JOIN t2 ON t1.a = t2.a
  WHERE t2.a IN (SELECT /*+ QB_NAME(subq1)  NO_BNL(t3, t4) */ t3.b
    FROM t3 JOIN t1 t4 ON t3.a = t4.b);

--echo # Make sure query results are the same for any hints combination
# --sorted_result
SELECT * FROM t1 JOIN t2 ON t1.a = t2.a WHERE
t2.a IN (SELECT t3.b FROM t3 JOIN t1 t4 ON t3.a = t4.b);
# --sorted_result
SELECT /*+ QB_NAME(q) */ * FROM t1 JOIN t2 ON t1.a = t2.a WHERE
t2.a IN (SELECT /*+ QB_NAME(subq1) */ t3.b FROM t3 JOIN t1 t4 ON t3.a = t4.b);
--sorted_result
SELECT /*+ QB_NAME(q) NO_BNL() */ *
  FROM t1 JOIN t2 ON t1.a = t2.a
  WHERE t2.a IN (SELECT /*+ QB_NAME(subq1) */ t3.b FROM t3 JOIN t1 t4 ON t3.a = t4.b);
--sorted_result
SELECT /*+ QB_NAME(q) NO_BNL(t1, t2) */ *
  FROM t1 JOIN t2 ON t1.a = t2.a
  WHERE t2.a IN (SELECT /*+ QB_NAME(subq1) */ t3.b FROM t3 JOIN t1 t4 ON t3.a = t4.b);
--sorted_result
SELECT /*+ QB_NAME(q) NO_BNL(@subq1) */ *
  FROM t1 JOIN t2 ON t1.a = t2.a
  WHERE t2.a IN (SELECT /*+ QB_NAME(subq1) */ t3.b FROM t3 JOIN t1 t4 ON t3.a = t4.b);
--sorted_result
SELECT /*+ QB_NAME(q) NO_BNL(t4@subq1) */ *
  FROM t1 JOIN t2 ON t1.a = t2.a
  WHERE t2.a IN (SELECT /*+ QB_NAME(subq1) */ t3.b FROM t3 JOIN t1 t4 ON t3.a = t4.b);
--sorted_result
SELECT /*+ QB_NAME(q) NO_BNL(t3@subq1,t4@subq1) */ *
  FROM t1 JOIN t2 ON t1.a = t2.a
  WHERE t2.a IN (SELECT /*+ QB_NAME(subq1) */ t3.b FROM t3 JOIN t1 t4 ON t3.a = t4.b);
--sorted_result
SELECT /*+ QB_NAME(q) NO_BNL(@subq1 t3, t4) */ *
  FROM t1 JOIN t2 ON t1.a = t2.a
  WHERE t2.a IN (SELECT /*+ QB_NAME(subq1) */ t3.b FROM t3 JOIN t1 t4 ON t3.a = t4.b);
--sorted_result
SELECT /*+ QB_NAME(q) */ *
  FROM t1 JOIN t2 ON t1.a = t2.a
  WHERE t2.a IN (SELECT /*+ QB_NAME(subq1)  NO_BNL(t3, t4) */ t3.b
    FROM t3 JOIN t1 t4 ON t3.a = t4.b);

DROP TABLE t1, t2, t3;

--echo #
--echo # BNL() and NO_BNL() for LEFT JOINs
--echo #

CREATE TABLE t1 (a int);
CREATE TABLE t2 (a int);
CREATE TABLE t3 (a int);
CREATE TABLE t4 (a int);

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

set join_cache_level = 8;

--echo # Two join buffers are employed by default (without hints):
EXPLAIN SELECT t1.a
  FROM t1 LEFT JOIN (t2 LEFT JOIN t3 ON t2.a) ON 0
    WHERE t1.a OR t3.a;

--echo # Disabling either of join buffers disables another one automatically due
--echo # to join buffer employment rules:
EXPLAIN SELECT /*+ NO_BNL(t2) */ t1.a
  FROM t1 LEFT JOIN (t2 LEFT JOIN t3 ON t2.a) ON 0
    WHERE t1.a OR t3.a;

EXPLAIN SELECT /*+ NO_BNL(t3) */ t1.a
  FROM t1 LEFT JOIN (t2 LEFT JOIN t3 ON t2.a) ON 0
    WHERE t1.a OR t3.a;

--echo # Three join buffers are employed here by default (without hints):
EXPLAIN SELECT t1.a
  FROM t1 LEFT JOIN (t2 LEFT JOIN (t3 LEFT JOIN t4 ON 1) ON t2.a) ON 0
    WHERE t1.a OR t4.a;

--echo # Disabling either of join buffers disables others automatically due
--echo # to join buffer employment rules:
EXPLAIN SELECT /*+ NO_BNL(t2)*/ t1.a
  FROM t1 LEFT JOIN (t2 LEFT JOIN (t3 LEFT JOIN t4 ON 1) ON t2.a) ON 0
    WHERE t1.a OR t4.a;
EXPLAIN SELECT /*+ NO_BNL(t3)*/ t1.a
  FROM t1 LEFT JOIN (t2 LEFT JOIN (t3 LEFT JOIN t4 ON 1) ON t2.a) ON 0
    WHERE t1.a OR t4.a;
EXPLAIN SELECT /*+ NO_BNL(t4)*/ t1.a
  FROM t1 LEFT JOIN (t2 LEFT JOIN (t3 LEFT JOIN t4 ON 1) ON t2.a) ON 0
    WHERE t1.a OR t4.a;

set join_cache_level=0;
--echo # It is not allowed to enable join buffers on some subset of inner tables
--echo # of an outer join. Either all tables should use join buffers or none:
EXPLAIN SELECT /*+ BNL(t2)*/ t1.a
  FROM t1 LEFT JOIN (t2 LEFT JOIN (t3 LEFT JOIN t4 ON 1) ON t2.a) ON 0
    WHERE t1.a OR t4.a;
EXPLAIN SELECT /*+ BNL(t2, t3)*/ t1.a
  FROM t1 LEFT JOIN (t2 LEFT JOIN (t3 LEFT JOIN t4 ON 1) ON t2.a) ON 0
    WHERE t1.a OR t4.a;
EXPLAIN SELECT /*+ BNL(t2, t3, t4)*/ t1.a
  FROM t1 LEFT JOIN (t2 LEFT JOIN (t3 LEFT JOIN t4 ON 1) ON t2.a) ON 0
    WHERE t1.a OR t4.a;

set join_cache_level=8;
INSERT INTO t2 VALUES (1), (2), (null), (1);
--echo # BNLH buffer is used when allowed by JCL setting
EXPLAIN SELECT * FROM t1, t2 WHERE t1.a=t2.a;

--echo # Make sure the hint enables BNL even when JCL=0:
set join_cache_level=0;
EXPLAIN SELECT /*+BNL(t2) */ * FROM t1, t2 WHERE t1.a=t2.a;

set join_cache_level=2;
EXPLAIN SELECT /*+BNL(t2) */ * FROM t1, t2 WHERE t1.a=t2.a;

DROP TABLE t1,t2,t3,t4;


--echo #
--echo # Mix of BNL/BKA flat and incremental join buffers for OUTER JOINs
--echo #

set optimizer_switch='outer_join_with_cache=on,mrr=on,mrr_sort_keys=on,index_condition_pushdown=on';

CREATE TABLE t1 (a1 varchar(32)) ;
INSERT INTO t1 VALUES ('s'),('k');

CREATE TABLE t2 (a2 int PRIMARY KEY, b2 varchar(32)) ;
INSERT INTO t2 VALUES (7,'s');

CREATE TABLE t3 (a3 int PRIMARY KEY, b3 varchar(32)) ;
INSERT INTO t3 VALUES (7,'s');

CREATE TABLE t4 (a4 int);
INSERT INTO t4 VALUES (9);

CREATE TABLE t5(a5 int PRIMARY KEY, b5 int) ;
INSERT INTO t5 VALUES (7,0);
--disable_result_log
ANALYZE TABLES t1, t2, t3, t4, t5;
--enable_result_log

--echo # Disable join buffering to enable it selectively on particular tables
SET SESSION join_cache_level = 0;
EXPLAIN
SELECT t4.a4, t5.b5
  FROM ((t1 LEFT JOIN (t2 JOIN t3 ON t2.a2 = t3.a3) ON t2.b2 = t1.a1)
       LEFT JOIN t4 ON t4.a4 <> 0) LEFT JOIN t5 ON t5.a5 = t2.a2;
SELECT t4.a4, t5.b5 
  FROM ((t1 LEFT JOIN (t2 JOIN t3 ON t2.a2 = t3.a3) ON t2.b2 = t1.a1)
       LEFT JOIN t4 ON t4.a4 <> 0) LEFT JOIN t5 ON t5.a5 = t2.a2;

EXPLAIN
SELECT /*+ BNL(t4) */ t4.a4, t5.b5
  FROM ((t1 LEFT JOIN (t2 JOIN t3 ON t2.a2 = t3.a3) ON t2.b2 = t1.a1)
       LEFT JOIN t4 ON t4.a4 <> 0) LEFT JOIN t5 ON t5.a5 = t2.a2;
SELECT /*+ BNL(t4) */ t4.a4, t5.b5
  FROM ((t1 LEFT JOIN (t2 JOIN t3 ON t2.a2 = t3.a3) ON t2.b2 = t1.a1)
       LEFT JOIN t4 ON t4.a4 <> 0) LEFT JOIN t5 ON t5.a5 = t2.a2;

EXPLAIN
SELECT /*+ BNL(t4, t5) */ t4.a4, t5.b5
  FROM ((t1 LEFT JOIN (t2 JOIN t3 ON t2.a2 = t3.a3) ON t2.b2 = t1.a1)
       LEFT JOIN t4 ON t4.a4 <> 0) LEFT JOIN t5 ON t5.a5 = t2.a2;
SELECT /*+ BNL(t4, t5) */ t4.a4, t5.b5
  FROM ((t1 LEFT JOIN (t2 JOIN t3 ON t2.a2 = t3.a3) ON t2.b2 = t1.a1)
       LEFT JOIN t4 ON t4.a4 <> 0) LEFT JOIN t5 ON t5.a5 = t2.a2;

--echo # BNL() hint overrides join_cache_levels from 0 to 3 increasing it to 4
set join_cache_level = 1;
EXPLAIN
SELECT /*+ BNL(t4, t5) */ t4.a4, t5.b5
  FROM ((t1 LEFT JOIN (t2 JOIN t3 ON t2.a2 = t3.a3) ON t2.b2 = t1.a1)
       LEFT JOIN t4 ON t4.a4 <> 0) LEFT JOIN t5 ON t5.a5 = t2.a2;

set join_cache_level = 2;
EXPLAIN
SELECT /*+ BNL(t4, t5) */ t4.a4, t5.b5
  FROM ((t1 LEFT JOIN (t2 JOIN t3 ON t2.a2 = t3.a3) ON t2.b2 = t1.a1)
       LEFT JOIN t4 ON t4.a4 <> 0) LEFT JOIN t5 ON t5.a5 = t2.a2;

set join_cache_level = 3;
EXPLAIN
SELECT /*+ BNL(t4, t5) */ t4.a4, t5.b5
  FROM ((t1 LEFT JOIN (t2 JOIN t3 ON t2.a2 = t3.a3) ON t2.b2 = t1.a1)
       LEFT JOIN t4 ON t4.a4 <> 0) LEFT JOIN t5 ON t5.a5 = t2.a2;

--echo # Enable all join buffering capabilities:
SET SESSION join_cache_level = 8;
EXPLAIN
SELECT t4.a4, t5.b5
  FROM ((t1 LEFT JOIN (t2 JOIN t3 ON t2.a2 = t3.a3) ON t2.b2 = t1.a1)
       LEFT JOIN t4 ON t4.a4 <> 0) LEFT JOIN t5 ON t5.a5 = t2.a2;
SELECT t4.a4, t5.b5
  FROM ((t1 LEFT JOIN (t2 JOIN t3 ON t2.a2 = t3.a3) ON t2.b2 = t1.a1)
       LEFT JOIN t4 ON t4.a4 <> 0) LEFT JOIN t5 ON t5.a5 = t2.a2;

EXPLAIN
SELECT /*+ NO_BNL(t4)*/ t4.a4, t5.b5
  FROM ((t1 LEFT JOIN (t2 JOIN t3 ON t2.a2 = t3.a3) ON t2.b2 = t1.a1)
       LEFT JOIN t4 ON t4.a4 <> 0) LEFT JOIN t5 ON t5.a5 = t2.a2;
SELECT /*+ NO_BNL(t4)*/ t4.a4, t5.b5
  FROM ((t1 LEFT JOIN (t2 JOIN t3 ON t2.a2 = t3.a3) ON t2.b2 = t1.a1)
       LEFT JOIN t4 ON t4.a4 <> 0) LEFT JOIN t5 ON t5.a5 = t2.a2;

--echo # Disable BKA so the BNLH join buffer will be employed:
EXPLAIN
SELECT /*+ NO_BKA(t5)*/ t4.a4, t5.b5
  FROM ((t1 LEFT JOIN (t2 JOIN t3 ON t2.a2 = t3.a3) ON t2.b2 = t1.a1)
       LEFT JOIN t4 ON t4.a4 <> 0) LEFT JOIN t5 ON t5.a5 = t2.a2;
SELECT /*+ NO_BKA(t5)*/ t4.a4, t5.b5
  FROM ((t1 LEFT JOIN (t2 JOIN t3 ON t2.a2 = t3.a3) ON t2.b2 = t1.a1)
       LEFT JOIN t4 ON t4.a4 <> 0) LEFT JOIN t5 ON t5.a5 = t2.a2;

EXPLAIN
SELECT /*+ NO_BKA(t5) NO_BNL(t5)*/ t4.a4, t5.b5
  FROM ((t1 LEFT JOIN (t2 JOIN t3 ON t2.a2 = t3.a3) ON t2.b2 = t1.a1)
       LEFT JOIN t4 ON t4.a4 <> 0) LEFT JOIN t5 ON t5.a5 = t2.a2;
SELECT /*+ NO_BKA(t5) NO_BNL(t5)*/ t4.a4, t5.b5
  FROM ((t1 LEFT JOIN (t2 JOIN t3 ON t2.a2 = t3.a3) ON t2.b2 = t1.a1)
       LEFT JOIN t4 ON t4.a4 <> 0) LEFT JOIN t5 ON t5.a5 = t2.a2;

DROP TABLE t1,t2,t3,t4,t5;

set @@join_cache_level= @tmp_jcl;
set @@optimizer_switch= @tmp_opt;