bzr commit into mysql-6.0 branch (igor:2637) Bug#37690

[Igor Babaev]

#At file:///home/igor/dev-bzr/mysql-6.0-bka-bug37690/

 2637 Igor Babaev	2008-07-03
      Fixed bug #37690 in the BKA code.
      Wrong choice of the upper limit value in a 'for' statement
      within the JOIN_CACHE_BKA_UNIQUE::init function caused
      crashes for executed queries if the size of the join buffer
      was set less than 256. 
modified:
  mysql-test/r/join_cache.result
  mysql-test/t/join_cache.test
  sql/sql_select.cc

per-file messages:
  mysql-test/r/join_cache.result
    Added a test case for bug #37690.
  mysql-test/t/join_cache.test
    Added a test case for bug #37690.
  sql/sql_select.cc
    Fixed the code of JOIN_CACHE_BKA_UNIQUE::init to make
    the problematic 'for' statement to work at least once.
=== modified file 'mysql-test/r/join_cache.result'
--- a/mysql-test/r/join_cache.result	2008-06-06 22:03:14 +0000
+++ b/mysql-test/r/join_cache.result	2008-07-04 03:23:40 +0000
@@ -3185,3 +3185,24 @@ a1<>a2	a1	a2	b2	b3	c3	s1	s2
 0	6	6	73	73	738		
 0	6	6	74	74	749		
 DROP TABLE t1,t2,t3;
+CREATE TABLE t1 (a int, b int, INDEX idx(b));
+CREATE TABLE t2 (a int, b int, INDEX idx(a));
+INSERT INTO t1 VALUES (5,30), (3,20), (7,40), (2,10), (8,30), (1,10), (4,20);
+INSERT INTO t2 VALUES (7,10), (1,20), (2,20), (8,20), (8,10), (1,20);
+INSERT INTO t2 VALUES (1,10), (4,20), (3,20), (7,20), (7,10), (1,20);
+set join_buffer_size=32;
+Warnings:
+Warning	1292	Truncated incorrect join_buffer_size value: '32'
+set join_cache_level=8;
+EXPLAIN SELECT * FROM t1,t2 WHERE t1.a=t2.a AND t1.b >= 30;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	ALL	idx	NULL	NULL	NULL	7	Using where
+1	SIMPLE	t2	ref	idx	idx	5	test.t1.a	2	Using join buffer
+SELECT * FROM t1,t2 WHERE t1.a=t2.a AND t1.b >= 30;
+a	b	a	b
+7	40	7	10
+8	30	8	20
+8	30	8	10
+7	40	7	20
+7	40	7	10
+DROP TABLE t1,t2;

=== modified file 'mysql-test/t/join_cache.test'
--- a/mysql-test/t/join_cache.test	2008-06-03 01:49:09 +0000
+++ b/mysql-test/t/join_cache.test	2008-07-04 03:23:40 +0000
@@ -750,3 +750,22 @@ SELECT a1<>a2, a1, a2, b2, b3, c3,
 FROM t1,t2,t3 WHERE a1=a2 AND b2=b3 AND MOD(c3,10)>7;
  
 DROP TABLE t1,t2,t3;
+
+#
+# Bug #37690: crash with a tiny buffer when using BKA_JOIN_CACHE_UNIQUE
+#
+
+CREATE TABLE t1 (a int, b int, INDEX idx(b));
+CREATE TABLE t2 (a int, b int, INDEX idx(a)); 
+INSERT INTO t1 VALUES (5,30), (3,20), (7,40), (2,10), (8,30), (1,10), (4,20);     
+INSERT INTO t2 VALUES (7,10), (1,20), (2,20), (8,20), (8,10), (1,20);
+INSERT INTO t2 VALUES (1,10), (4,20), (3,20), (7,20), (7,10), (1,20); 
+    
+set join_buffer_size=32; 
+set join_cache_level=8;  
+ 
+EXPLAIN SELECT * FROM t1,t2 WHERE t1.a=t2.a AND t1.b >= 30;   
+SELECT * FROM t1,t2 WHERE t1.a=t2.a AND t1.b >= 30;  
+
+DROP TABLE t1,t2;
+ 
\ No newline at end of file

=== modified file 'sql/sql_select.cc'
--- a/sql/sql_select.cc	2008-06-12 04:27:24 +0000
+++ b/sql/sql_select.cc	2008-07-04 03:23:40 +0000
@@ -18937,9 +18937,10 @@ int JOIN_CACHE_BKA_UNIQUE::init()
   /* Take into account a reference to the next record in the key chain */
   pack_length+= get_size_of_rec_offset(); 
  
-  /* Calculate the minimal possible value of size_of_key_ofs greater than 1 */  
+  /* Calculate the minimal possible value of size_of_key_ofs greater than 2 */
+  uint max_size_of_key_ofs= max(2, get_size_of_rec_offset());  
   for (size_of_key_ofs= 2;
-       size_of_key_ofs <= get_size_of_rec_offset();
+       size_of_key_ofs <= max_size_of_key_ofs;
        size_of_key_ofs+= 2)
   {    
     key_entry_length= get_size_of_rec_offset() + // key chain header