#
# 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.
#
CREATE PROCEDURE insert_n(start int, end int)
BEGIN
DECLARE i INT DEFAULT start;
WHILE i <= end do
INSERT INTO t1 VALUES (1, 2, 3) ON DUPLICATE KEY UPDATE c = i;
SET i = i + 1;
END WHILE;
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;
InnoDB		0 transactions not purged
BEGIN;
SELECT * FROM t1;
a	b	c
#
# Create 100 newer record versions in con2 and con3
#
connect  con2, localhost, root,,;
connection con2;
BEGIN;
INSERT INTO t1 VALUES (1, 2, 3) ON DUPLICATE KEY UPDATE c = NULL;
CALL insert_n(1, 50);;
connect  con3, localhost, root,,;
connection con3;
BEGIN;
CALL insert_n(51, 100);;
connection con2;
COMMIT;
connection con3;
INSERT INTO t1 VALUES (1, 2, 1) ON DUPLICATE KEY UPDATE c = NULL;
COMMIT;
connection default;
#
# Connect to default and record how many pages were accessed
# when selecting the record using the secondary key.
#
InnoDB		2 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;
DROP TABLE t1;
DROP PROCEDURE insert_n;
DROP FUNCTION num_pages_get;