DBIx::Classでhas_manyするとLEFT JOINになる

こういうデータベースを作って

CREATE TABLE table1(
    id integer PRIMARY KEY,
    data1 text
);

CREATE TABLE table2(
    table1_id integer REFERENCES table1(id) PRIMARY KEY,
    data2 text
);

INSERT INTO table1 VALUES(1, '1-1');
INSERT INTO table1 VALUES(2, '1-2');
INSERT INTO table2 VALUES(1, '2-1');

こういうスクリプトを

package TestDB::Schema;

use base qw/DBIx::Class::Schema::Loader/;

__PACKAGE__->loader_options(
    relationships => 1,
    debug => 1
);

1;

package main;

my $schema1 = TestDB::Schema->connect("dbi:SQLite:dbname=testdb.db","","",undef);
my @rs = $schema1->resultset('Table1')->search(undef,
    {join => ['table2s']}
);

print "\n";

実行する。

% DBIC_TRACE=1 perl join.pl
TestDB::Schema::Table1->load_components("PK::Auto", "Core");
TestDB::Schema::Table2->load_components("PK::Auto", "Core");
TestDB::Schema::Table1->table("table1");
TestDB::Schema::Table1->add_columns(
  "id",
  { data_type => "integer", is_nullable => 0, size => undef },
  "data1",
  { data_type => "text", is_nullable => 0, size => undef },
);
TestDB::Schema::Table1->set_primary_key("id");
TestDB::Schema::Table2->table("table2");
TestDB::Schema::Table2->add_columns(
  "table1_id",
  { data_type => "integer", is_nullable => 0, size => undef },
  "data2",
  { data_type => "text", is_nullable => 0, size => undef },
);
TestDB::Schema::Table2->set_primary_key("table1_id");
TestDB::Schema::Table1->has_many(
  "table2s",
  "TestDB::Schema::Table2",
  { "foreign.table1_id" => "self.id" },
);
TestDB::Schema::Table2->belongs_to("table1_id", "TestDB::Schema::Table1", { id => "table1_id" });
SELECT me.id, me.data1 FROM table1 me LEFT JOIN table2 table2s ON ( table2s.table1_id = me.id ):

DBIx::Class::RelationshipのperldocにもLEFT JOINを生成するとか書いてある。