#!/perl
use strict;
use warnings FATAL => qw(all);

use DBI;
use File::Spec;
use Time::HiRes qw (time);

my $MEMORY = 1;

my $start = time;
my $PATH = "C:/TMP/___TMP/_TRASH";
my $dbfile = File::Spec->catdir($PATH, 'Big_DB.db');

my $dbh;
if (1 == $MEMORY)
{
	$dbh = DBI->connect('dbi:SQLite:dbname=:memory:',"","",{RaiseError => 1}) or die "Couldn't connect to database: " . DBI->errstr;
}
else

{
	$dbh = DBI->connect("dbi:SQLite:dbname=$dbfile","","",{RaiseError => 1}) or die "Couldn't connect to database: " . DBI->errstr;
}
print "Time till connect: ", time() - $start, $/;
$start = time;

if (1 == $MEMORY)
{    
	$dbh->sqlite_backup_from_file($dbfile);
}


print "Time till load: ", time() - $start, $/;
$start = time;
# Marker.
my $sth = $dbh->prepare("select Name, Writeups from employees e, groups g where e.Level = g.Level and g.Level = 'Pope (28)' order by e.Writeups desc ");

print "Time till prepare: ", time() - $start, $/;
$start = time;

$sth->execute();

print "Time till execute: ", time() - $start, $/;
$start = time;
my $answer = 0;

while ( my ($name, $writeups) = $sth->fetchrow_array )
{
	$answer += 1; # print join(';', ($name, $writeups)), $/;
}
print "Answer: $answer\n";


print "Time after loop: ", time() - $start, $/;
$start = time;

$dbh->disconnect;

##</code><code>##

Time till connect: 0.0150408744812012
Time till load: 4.3910698890686
Time till prepare: 0.000697851181030273
Time till execute: 0.110021829605103
Answer: 40000
Time after loop: 0.16477108001709

##</code><code>##

my $sql = "select Name, Writeups from employees e, groups g where e.Level = g.Level and g.Level = 'Pope (28)' order by e.Writeups desc ";

my $answer = 0;


for my $emp (@{$dbh->selectall_arrayref($sql, {Slice => {}})}) 
{
	$answer += 1;
}
print "Answer: $answer\n";

print "Time after loop: ", time() - $start, $/;
$start = time;
$dbh->disconnect;

##</code><code>##

Time till connect: 0.0147781372070313
Time till load: 4.42248010635376
Answer: 40000
Time after loop: 0.415067911148071

##</code><code>##

#!/perl
use strict;
use warnings FATAL => qw(all);

use DBI;
use File::Spec;
use Benchmark qw(:all) ;

my $PATH = "C:/TMP/___TMP/_TRASH";
my $dbfile = File::Spec->catdir($PATH, 'Big_DB.db');

my $MEMORY = 1;

my $dbh;
if (1 == $MEMORY)
{
	$dbh = DBI->connect('dbi:SQLite:dbname=:memory:',"","",{RaiseError => 1}) or die "Couldn't connect to database: " . DBI->errstr;
}
else
{
	$dbh = DBI->connect("dbi:SQLite:dbname=$dbfile","","",{RaiseError => 1}) or die "Couldn't connect to database: " . DBI->errstr;
}

if (1 == $MEMORY)
{    
	$dbh->sqlite_backup_from_file($dbfile);
}

cmpthese(-3, {
        'PrepExec' => sub 
	   { 
		my $sth = $dbh->prepare("select Name, Writeups from employees e, groups g where e.Level = g.Level and g.Level = 'Pope (28)' order by e.Writeups desc ");
		$sth->execute();
		
		my $answer = 0;
		
		
		while ( my ($name, $writeups) = $sth->fetchrow_array )
		{
			$answer += 1; # print join(';', ($name, $writeups)), $/;
		}
	   },
        'selectall' => sub 
	   { 
		my $sql = "select Name, Writeups from employees e, groups g where e.Level = g.Level and g.Level = 'Pope (28)' order by e.Writeups desc ";

		my $answer = 0;
		for my $emp (@{$dbh->selectall_arrayref($sql, {Slice => {}})}) 
		{
			$answer += 1;
		}
	   },
    });

$dbh->disconnect;    

##</code><code>##

            Rate selectall  PrepExec
selectall 2.88/s        --      -26%
PrepExec  3.90/s       35%        --

##</code><code>##

            Rate selectall  PrepExec
selectall 2.69/s        --      -25%
PrepExec  3.57/s       33%        --