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
|
# $Id$
# demonstrates that not fetching all of a result-set makes can make
# a difference. More recent MS SQL Server drivers are better at this so don't
# be surprised if this shows no difference between the 2 variations.
# However, in the past, cancelling a big select when you have not selected
# all rows has made a huge difference as MS SQL Server sees the cancel and
# stops sending the result-set.
use DBI;
use strict;
use warnings;
use Benchmark;
use Data::Dumper;
my $h = DBI->connect();
if (@ARGV) {
local $h->{PrintError} = 0;
eval {
$h->do(q/drop table mjebig/);
};
$h->do(q/create table mjebig(a varchar(255))/);
$h->begin_work; # quicker than autocommit
my $val = 'a' x 255;
my $s = $h->prepare(q/insert into mjebig values(?)/);
foreach (1..100000) {
$s->execute($val);
}
$h->commit;
}
sub one
{
my $s = $h->prepare(q/select * from mjebig/);
$s->execute;
$s->fetch;
$s = undef;
}
sub two
{
my $s = $h->prepare(q/select * from mjebig/);
$s->execute;
$s->fetch;
my $x = $s->cancel;
#print Dumper(\$x), "\n";
$s = undef;
}
timethese(1000, {
'without_cancel' => sub{one()},
'with_cancel' => sub{two()}
});
|
