perlquestion
punkish
I am trying to learn memcached, so I installed it on my laptop and fired it up. I also created a simple SQLite db 'mem.sqlite' like so
<p>
<code>
CREATE TABLE t (id INTEGER PRIMARY KEY, str TEXT)
</code>
<p>
and filled the table with 20_000 random strings. Then I used the following simplistic script to benchmark.
<p>
<code>
use Cache::Memcached;
my $memd = new Cache::Memcached {'servers' => [ "localhost:11212" ]};
use DBI qw(:sql_types);
my $dbh = DBI->connect("dbi:SQLite:dbname=mem.sqlite");
use Benchmark qw(:all);
my $count = 40_000;
cmpthese($count, {
'query_dbh' => sub {
my $id = int(rand(20_000));
my $sth = $dbh->prepare("SELECT str FROM t WHERE id = ?");
$sth->execute($id);
my ($str) = $sth->fetchrow_array;
open F, ">", "foo.txt" or die $!;
print F "id: $id, str: $str\n";
close F;
},
'query_mem' => sub {
my $id = int(rand(20_000));
open F, ">", "foo.txt" or die $!;
my $str = $memd->get($id);
unless ($str) {
my $sth = $dbh->prepare("SELECT str FROM t WHERE id = ?");
$sth->execute($id);
($str) = $sth->fetchrow_array;
$memd->set($id, $str);
}
print F "id: $id, str: $str\n";
close F;
}
});
Rate query_mem query_dbf
query_mem 2723/s -- -29%
query_dbh 3846/s 41% --
</code>
<p>
I consistently get results such as above, while I expected the memcache to slowly fill up and speed up the queries way faster than only accessing the file based db. What am I doing wrong, or are my expectations wrong?
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