1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
|
#
# Bug #84958 InnoDB's MVCC has O(N^2) behaviors
# https://bugs.mysql.com/bug.php?id=84958
#
# Set up the test with a procedure and a function.
#
SET @saved_frequency= @@GLOBAL.innodb_purge_rseg_truncate_frequency;
SET GLOBAL innodb_purge_rseg_truncate_frequency= 1;
CREATE PROCEDURE insert_n(start int, end int)
BEGIN
DECLARE i INT DEFAULT start;
START TRANSACTION;
WHILE i <= end do
INSERT INTO t1 VALUES (1, 2, 3) ON DUPLICATE KEY UPDATE c = i;
SET i = i + 1;
END WHILE;
COMMIT;
END~~
CREATE FUNCTION num_pages_get()
RETURNS INT
BEGIN
DECLARE ret INT;
SELECT variable_value INTO ret
FROM information_schema.global_status
WHERE variable_name = 'innodb_buffer_pool_read_requests';
RETURN ret;
END~~
#
# Create a table with one record in it and start an RR transaction
#
CREATE TABLE t1 (a INT, b INT, c INT, PRIMARY KEY(a,b), KEY (b,c))
ENGINE=InnoDB STATS_PERSISTENT=0;
BEGIN;
SELECT * FROM t1;
a b c
#
# Create 100 newer record versions in con2 and con3
#
connect con2, localhost, root,,;
connection con2;
INSERT INTO t1 VALUES (1, 2, 3) ON DUPLICATE KEY UPDATE c = NULL;
CALL insert_n(1, 50);;
connect con3, localhost, root,,;
connection con3;
CALL insert_n(51, 100);;
connection con2;
connection con3;
INSERT INTO t1 VALUES (1, 2, 1) ON DUPLICATE KEY UPDATE c = NULL;
connection default;
#
# Connect to default and record how many pages were accessed
# when selecting the record using the secondary key.
#
InnoDB 4 transactions not purged
SET @num_pages_1 = num_pages_get();
SELECT * FROM t1 force index (b);
a b c
SET @num_pages_2= num_pages_get();
SELECT IF(@num_pages_2 - @num_pages_1 < 5000, 'OK', @num_pages_2 - @num_pages_1) num_pages_diff;
num_pages_diff
OK
#
# Commit and show the final record.
#
SELECT * FROM t1;
a b c
SELECT * FROM t1 force index (b);
a b c
COMMIT;
SELECT * FROM t1 force index (b);
a b c
1 2 NULL
SELECT * FROM t1;
a b c
1 2 NULL
CHECK TABLE t1;
Table Op Msg_type Msg_text
test.t1 check status OK
#
# Cleanup
#
disconnect con2;
disconnect con3;
SET GLOBAL innodb_purge_rseg_truncate_frequency= @saved_frequency;
DROP TABLE t1;
DROP PROCEDURE insert_n;
DROP FUNCTION num_pages_get;
|
