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
|
DROP TABLE IF EXISTS t1;
CREATE TABLE t1 (a INT, INDEX (a));
INSERT INTO t1 VALUES (),(),(),(),(),(),(),(),(),();
FLUSH STATUS;
SELECT a FROM t1 ORDER BY a LIMIT 1;
a
NULL
SHOW STATUS LIKE 'HANDLER_READ%';
Variable_name Value
Handler_read_first 1
Handler_read_key 0
Handler_read_last 0
Handler_read_next 0
Handler_read_prev 0
Handler_read_rnd 0
Handler_read_rnd_next 0
FLUSH STATUS;
SELECT a FROM t1 ORDER BY a DESC LIMIT 1;
a
NULL
SHOW STATUS LIKE 'HANDLER_READ%';
Variable_name Value
Handler_read_first 0
Handler_read_key 0
Handler_read_last 1
Handler_read_next 0
Handler_read_prev 0
Handler_read_rnd 0
Handler_read_rnd_next 0
FLUSH STATUS;
SELECT a FROM t1 ORDER BY a LIMIT 3;
a
NULL
NULL
NULL
SHOW STATUS LIKE 'HANDLER_READ%';
Variable_name Value
Handler_read_first 1
Handler_read_key 0
Handler_read_last 0
Handler_read_next 2
Handler_read_prev 0
Handler_read_rnd 0
Handler_read_rnd_next 0
FLUSH STATUS;
SELECT a FROM t1 ORDER BY a DESC LIMIT 3;
a
NULL
NULL
NULL
SHOW STATUS LIKE 'HANDLER_READ%';
Variable_name Value
Handler_read_first 0
Handler_read_key 0
Handler_read_last 1
Handler_read_next 0
Handler_read_prev 2
Handler_read_rnd 0
Handler_read_rnd_next 0
DROP TABLE t1;
|
