Fixed bug mdev-449.

The bug could caused a crash when the server executed a query with
ORDER by and sort_buffer_size was set to a small enough number.
It happened because the small sort buffer did not allow to allocate
all merge buffers in it.
Made sure that the allocated sort buffer would be big enough
to contain all possible merge buffers.  

1 files changed, 132 insertions, 0 deletions

diff --git a/mysql-test/r/order_by.result b/mysql-test/r/order_by.result
index c0a54817b4c..8fa1006b8fc 100644
--- a/mysql-test/r/order_by.result
+++ b/mysql-test/r/order_by.result
@@ -1783,3 +1783,135 @@ Warnings:
 Note	1003	select `test`.`t2`.`b` AS `b` from `test`.`t1` join `test`.`t2` where (`test`.`t2`.`a` = `test`.`t1`.`b`) group by `test`.`t2`.`b` order by `test`.`t1`.`b`
 drop table t1,t2;
 End of 5.2 tests
+#
+# Bug mdev-449: ORDER BY with small sort_buffer_size
+#
+CREATE TABLE t1(f0 int auto_increment primary key, f1 int, f2 varchar(200));
+INSERT INTO t1(f1, f2) VALUES 
+(0,"0"),(1,"1"),(2,"2"),(3,"3"),(4,"4"),(5,"5"),
+(6,"6"),(7,"7"),(8,"8"),(9,"9"),(10,"10"),
+(11,"11"),(12,"12"),(13,"13"),(14,"14"),(15,"15"),
+(16,"16"),(17,"17"),(18,"18"),(19,"19"),(20,"20"),
+(21,"21"),(22,"22"),(23,"23"),(24,"24"),(25,"25"),
+(26,"26"),(27,"27"),(28,"28"),(29,"29"),(30,"30"),
+(31,"31"),(32,"32"),(33,"33"),(34,"34"),(35,"35"),
+(36,"36"),(37,"37"),(38,"38"),(39,"39"),(40,"40"),
+(41,"41"),(42,"42"),(43,"43"),(44,"44"),(45,"45"),
+(46,"46"),(47,"47"),(48,"48"),(49,"49"),(50,"50"),
+(51,"51"),(52,"52"),(53,"53"),(54,"54"),(55,"55"),
+(56,"56"),(57,"57"),(58,"58"),(59,"59"),(60,"60"),
+(61,"61"),(62,"62"),(63,"63"),(64,"64"),(65,"65"),
+(66,"66"),(67,"67"),(68,"68"),(69,"69"),(70,"70"),
+(71,"71"),(72,"72"),(73,"73"),(74,"74"),(75,"75"),
+(76,"76"),(77,"77"),(78,"78"),(79,"79"),(80,"80"),
+(81,"81"),(82,"82"),(83,"83"),(84,"84"),(85,"85"),
+(86,"86"),(87,"87"),(88,"88"),(89,"89"),(90,"90"),
+(91,"91"),(92,"92"),(93,"93"),(94,"94"),(95,"95"),
+(96,"96"),(97,"97"),(98,"98"),(99,"99");
+set @save_sort_buffer_size= @@sort_buffer_size;
+set sort_buffer_size= 2000;
+SELECT * FROM t1 ORDER BY f1 DESC, f0;
+f0	f1	f2
+100	99	99
+99	98	98
+98	97	97
+97	96	96
+96	95	95
+95	94	94
+94	93	93
+93	92	92
+92	91	91
+91	90	90
+90	89	89
+89	88	88
+88	87	87
+87	86	86
+86	85	85
+85	84	84
+84	83	83
+83	82	82
+82	81	81
+81	80	80
+80	79	79
+79	78	78
+78	77	77
+77	76	76
+76	75	75
+75	74	74
+74	73	73
+73	72	72
+72	71	71
+71	70	70
+70	69	69
+69	68	68
+68	67	67
+67	66	66
+66	65	65
+65	64	64
+64	63	63
+63	62	62
+62	61	61
+61	60	60
+60	59	59
+59	58	58
+58	57	57
+57	56	56
+56	55	55
+55	54	54
+54	53	53
+53	52	52
+52	51	51
+51	50	50
+50	49	49
+49	48	48
+48	47	47
+47	46	46
+46	45	45
+45	44	44
+44	43	43
+43	42	42
+42	41	41
+41	40	40
+40	39	39
+39	38	38
+38	37	37
+37	36	36
+36	35	35
+35	34	34
+34	33	33
+33	32	32
+32	31	31
+31	30	30
+30	29	29
+29	28	28
+28	27	27
+27	26	26
+26	25	25
+25	24	24
+24	23	23
+23	22	22
+22	21	21
+21	20	20
+20	19	19
+19	18	18
+18	17	17
+17	16	16
+16	15	15
+15	14	14
+14	13	13
+13	12	12
+12	11	11
+11	10	10
+10	9	9
+9	8	8
+8	7	7
+7	6	6
+6	5	5
+5	4	4
+4	3	3
+3	2	2
+2	1	1
+1	0	0
+set sort_buffer_size= @save_sort_buffer_size;
+DROP TABLE t1;
+End of 5.3 tests