package DBIx::Class::Storage::DBI::Replicated;
BEGIN {
use DBIx::Class;
die('The following modules are required for Replication ' . DBIx::Class::Optional::Dependencies->req_missing_for ('replicated') . "\n" )
unless DBIx::Class::Optional::Dependencies->req_ok_for ('replicated');
}
use Moose;
use DBIx::Class::Storage::DBI;
use DBIx::Class::Storage::DBI::Replicated::Pool;
use DBIx::Class::Storage::DBI::Replicated::Balancer;
use DBIx::Class::Storage::DBI::Replicated::Types qw/BalancerClassNamePart DBICSchema DBICStorageDBI/;
use MooseX::Types::Moose qw/ClassName HashRef Object/;
use Scalar::Util 'reftype';
use Hash::Merge;
use List::Util qw/min max reduce/;
use Context::Preserve 'preserve_context';
use Try::Tiny;
use namespace::clean -except => 'meta';
=encoding utf8
=head1 NAME
DBIx::Class::Storage::DBI::Replicated - BETA Replicated database support
=head1 SYNOPSIS
The Following example shows how to change an existing $schema to a replicated
storage type, add some replicated (read-only) databases, and perform reporting
tasks.
You should set the 'storage_type attribute to a replicated type. You should
also define your arguments, such as which balancer you want and any arguments
that the Pool object should get.
my $schema = Schema::Class->clone;
$schema->storage_type( ['::DBI::Replicated', {balancer=>'::Random'}] );
$schema->connection(...);
Next, you need to add in the Replicants. Basically this is an array of
arrayrefs, where each arrayref is database connect information. Think of these
arguments as what you'd pass to the 'normal' $schema->connect method.
$schema->storage->connect_replicants(
[$dsn1, $user, $pass, \%opts],
[$dsn2, $user, $pass, \%opts],
[$dsn3, $user, $pass, \%opts],
);
Now, just use the $schema as you normally would. Automatically all reads will
be delegated to the replicants, while writes to the master.
$schema->resultset('Source')->search({name=>'etc'});
You can force a given query to use a particular storage using the search
attribute 'force_pool'. For example:
my $rs = $schema->resultset('Source')->search(undef, {force_pool=>'master'});
Now $rs will force everything (both reads and writes) to use whatever was setup
as the master storage. 'master' is hardcoded to always point to the Master,
but you can also use any Replicant name. Please see:
L<DBIx::Class::Storage::DBI::Replicated::Pool> and the replicants attribute for more.
Also see transactions and L</execute_reliably> for alternative ways to
force read traffic to the master. In general, you should wrap your statements
in a transaction when you are reading and writing to the same tables at the
same time, since your replicants will often lag a bit behind the master.
If you have a multi-statement read only transaction you can force it to select
a random server in the pool by:
my $rs = $schema->resultset('Source')->search( undef,
{ force_pool => $db->storage->read_handler->next_storage }
);
=head1 DESCRIPTION
Warning: This class is marked BETA. This has been running a production
website using MySQL native replication as its backend and we have some decent
test coverage but the code hasn't yet been stressed by a variety of databases.
Individual DBs may have quirks we are not aware of. Please use this in first
development and pass along your experiences/bug fixes.
This class implements replicated data store for DBI. Currently you can define
one master and numerous slave database connections. All write-type queries
(INSERT, UPDATE, DELETE and even LAST_INSERT_ID) are routed to master
database, all read-type queries (SELECTs) go to the slave database.
Basically, any method request that L<DBIx::Class::Storage::DBI> would normally
handle gets delegated to one of the two attributes: L</read_handler> or to
L</write_handler>. Additionally, some methods need to be distributed
to all existing storages. This way our storage class is a drop in replacement
for L<DBIx::Class::Storage::DBI>.
Read traffic is spread across the replicants (slaves) occurring to a user
selected algorithm. The default algorithm is random weighted.
=head1 NOTES
The consistency between master and replicants is database specific. The Pool
gives you a method to validate its replicants, removing and replacing them
when they fail/pass predefined criteria. Please make careful use of the ways
to force a query to run against Master when needed.
=head1 REQUIREMENTS
Replicated Storage has additional requirements not currently part of
L<DBIx::Class>. See L<DBIx::Class::Optional::Dependencies> for more details.
=head1 ATTRIBUTES
This class defines the following attributes.
=head2 schema
The underlying L<DBIx::Class::Schema> object this storage is attaching
=cut
has 'schema' => (
is=>'rw',
isa=>DBICSchema,
weak_ref=>1,
required=>1,
);
=head2 pool_type
Contains the classname which will instantiate the L</pool> object. Defaults
to: L<DBIx::Class::Storage::DBI::Replicated::Pool>.
=cut
has 'pool_type' => (
is=>'rw',
isa=>ClassName,
default=>'DBIx::Class::Storage::DBI::Replicated::Pool',
handles=>{
'create_pool' => 'new',
},
);
=head2 pool_args
Contains a hashref of initialized information to pass to the Balancer object.
See L<DBIx::Class::Storage::DBI::Replicated::Pool> for available arguments.
=cut
has 'pool_args' => (
is=>'rw',
isa=>HashRef,
lazy=>1,
default=>sub { {} },
);
=head2 balancer_type
The replication pool requires a balance class to provider the methods for
choose how to spread the query load across each replicant in the pool.
=cut
has 'balancer_type' => (
is=>'rw',
isa=>BalancerClassNamePart,
coerce=>1,
required=>1,
default=> 'DBIx::Class::Storage::DBI::Replicated::Balancer::First',
handles=>{
'create_balancer' => 'new',
},
);
=head2 balancer_args
Contains a hashref of initialized information to pass to the Balancer object.
See L<DBIx::Class::Storage::DBI::Replicated::Balancer> for available arguments.
=cut
has 'balancer_args' => (
is=>'rw',
isa=>HashRef,
lazy=>1,
required=>1,
default=>sub { {} },
);
=head2 pool
Is a L<DBIx::Class::Storage::DBI::Replicated::Pool> or derived class. This is a
container class for one or more replicated databases.
=cut
has 'pool' => (
is=>'ro',
isa=>'DBIx::Class::Storage::DBI::Replicated::Pool',
lazy_build=>1,
handles=>[qw/
connect_replicants
replicants
has_replicants
/],
);
=head2 balancer
Is a L<DBIx::Class::Storage::DBI::Replicated::Balancer> or derived class. This
is a class that takes a pool (L<DBIx::Class::Storage::DBI::Replicated::Pool>)
=cut
has 'balancer' => (
is=>'rw',
isa=>'DBIx::Class::Storage::DBI::Replicated::Balancer',
lazy_build=>1,
handles=>[qw/auto_validate_every/],
);
=head2 master
The master defines the canonical state for a pool of connected databases. All
the replicants are expected to match this databases state. Thus, in a classic
Master / Slaves distributed system, all the slaves are expected to replicate
the Master's state as quick as possible. This is the only database in the
pool of databases that is allowed to handle write traffic.
=cut
has 'master' => (
is=> 'ro',
isa=>DBICStorageDBI,
lazy_build=>1,
);
=head1 ATTRIBUTES IMPLEMENTING THE DBIx::Storage::DBI INTERFACE
The following methods are delegated all the methods required for the
L<DBIx::Class::Storage::DBI> interface.
=cut
my $method_dispatch = {
writer => [qw/
on_connect_do
on_disconnect_do
on_connect_call
on_disconnect_call
connect_info
_connect_info
throw_exception
sql_maker
sqlt_type
create_ddl_dir
deployment_statements
datetime_parser
datetime_parser_type
build_datetime_parser
last_insert_id
insert
insert_bulk
update
delete
dbh
txn_begin
txn_do
txn_commit
txn_rollback
txn_scope_guard
_exec_txn_rollback
_exec_txn_begin
_exec_txn_commit
deploy
with_deferred_fk_checks
dbh_do
_prep_for_execute
is_datatype_numeric
_count_select
svp_rollback
svp_begin
svp_release
relname_to_table_alias
_dbh_last_insert_id
_default_dbi_connect_attributes
_dbi_connect_info
_dbic_connect_attributes
auto_savepoint
_query_start
_query_end
_format_for_trace
_dbi_attrs_for_bind
bind_attribute_by_data_type
transaction_depth
_dbh
_select_args
_dbh_execute_for_fetch
_sql_maker
_dbh_execute_inserts_with_no_binds
_select_args_to_query
_gen_sql_bind
_svp_generate_name
_normalize_connect_info
_parse_connect_do
savepoints
_sql_maker_opts
_conn_pid
_dbh_autocommit
_native_data_type
_get_dbh
sql_maker_class
_execute
_do_query
_sth
_dbh_sth
_dbh_execute
/, Class::MOP::Class->initialize('DBIx::Class::Storage::DBIHacks')->get_method_list ],
reader => [qw/
select
select_single
columns_info_for
_dbh_columns_info_for
_select
/],
unimplemented => [qw/
_arm_global_destructor
_verify_pid
source_bind_attributes
get_use_dbms_capability
set_use_dbms_capability
get_dbms_capability
set_dbms_capability
_dbh_details
_dbh_get_info
sql_limit_dialect
sql_quote_char
sql_name_sep
_prefetch_autovalues
_perform_autoinc_retrieval
_autoinc_supplied_for_op
_resolve_bindattrs
_max_column_bytesize
_is_lob_type
_is_binary_lob_type
_is_binary_type
_is_text_lob_type
sth
/,(
# the capability framework
# not sure if CMOP->initialize does evil things to DBIC::S::DBI, fix if a problem
grep
{ $_ =~ /^ _ (?: use | supports | determine_supports ) _ /x }
( Class::MOP::Class->initialize('DBIx::Class::Storage::DBI')->get_all_method_names )
)],
};
if (DBIx::Class::_ENV_::DBICTEST) {
my $seen;
for my $type (keys %$method_dispatch) {
for (@{$method_dispatch->{$type}}) {
push @{$seen->{$_}}, $type;
}
}
if (my @dupes = grep { @{$seen->{$_}} > 1 } keys %$seen) {
die(join "\n", '',
'The following methods show up multiple times in ::Storage::DBI::Replicated handlers:',
(map { "$_: " . (join ', ', @{$seen->{$_}}) } sort @dupes),
'',
);
}
if (my @cant = grep { ! DBIx::Class::Storage::DBI->can($_) } keys %$seen) {
die(join "\n", '',
'::Storage::DBI::Replicated specifies handling of the following *NON EXISTING* ::Storage::DBI methods:',
@cant,
'',
);
}
}
for my $method (@{$method_dispatch->{unimplemented}}) {
__PACKAGE__->meta->add_method($method, sub {
my $self = shift;
$self->throw_exception("$method must not be called on ".(blessed $self).' objects');
});
}
=head2 read_handler
Defines an object that implements the read side of L<BIx::Class::Storage::DBI>.
=cut
has 'read_handler' => (
is=>'rw',
isa=>Object,
lazy_build=>1,
handles=>$method_dispatch->{reader},
);
=head2 write_handler
Defines an object that implements the write side of L<BIx::Class::Storage::DBI>,
as well as methods that don't write or read that can be called on only one
storage, methods that return a C<$dbh>, and any methods that don't make sense to
run on a replicant.
=cut
has 'write_handler' => (
is=>'ro',
isa=>Object,
lazy_build=>1,
handles=>$method_dispatch->{writer},
);
has _master_connect_info_opts =>
(is => 'rw', isa => HashRef, default => sub { {} });
=head2 around: connect_info
Preserves master's C<connect_info> options (for merging with replicants.)
Also sets any Replicated-related options from connect_info, such as
C<pool_type>, C<pool_args>, C<balancer_type> and C<balancer_args>.
=cut
around connect_info => sub {
my ($next, $self, $info, @extra) = @_;
my $merge = Hash::Merge->new('LEFT_PRECEDENT');
my %opts;
for my $arg (@$info) {
next unless (reftype($arg)||'') eq 'HASH';
%opts = %{ $merge->merge($arg, \%opts) };
}
delete $opts{dsn};
if (@opts{qw/pool_type pool_args/}) {
$self->pool_type(delete $opts{pool_type})
if $opts{pool_type};
$self->pool_args(
$merge->merge((delete $opts{pool_args} || {}), $self->pool_args)
);
## Since we possibly changed the pool_args, we need to clear the current
## pool object so that next time it is used it will be rebuilt.
$self->clear_pool;
}
if (@opts{qw/balancer_type balancer_args/}) {
$self->balancer_type(delete $opts{balancer_type})
if $opts{balancer_type};
$self->balancer_args(
$merge->merge((delete $opts{balancer_args} || {}), $self->balancer_args)
);
$self->balancer($self->_build_balancer)
if $self->balancer;
}
$self->_master_connect_info_opts(\%opts);
return preserve_context {
$self->$next($info, @extra);
} after => sub {
# Make sure master is blessed into the correct class and apply role to it.
my $master = $self->master;
$master->_determine_driver;
Moose::Meta::Class->initialize(ref $master);
DBIx::Class::Storage::DBI::Replicated::WithDSN->meta->apply($master);
# link pool back to master
$self->pool->master($master);
};
};
=head1 METHODS
This class defines the following methods.
=head2 BUILDARGS
L<DBIx::Class::Schema> when instantiating its storage passed itself as the
first argument. So we need to massage the arguments a bit so that all the
bits get put into the correct places.
=cut
sub BUILDARGS {
my ($class, $schema, $storage_type_args, @args) = @_;
return {
schema=>$schema,
%$storage_type_args,
@args
}
}
=head2 _build_master
Lazy builder for the L</master> attribute.
=cut
sub _build_master {
my $self = shift @_;
my $master = DBIx::Class::Storage::DBI->new($self->schema);
$master
}
=head2 _build_pool
Lazy builder for the L</pool> attribute.
=cut
sub _build_pool {
my $self = shift @_;
$self->create_pool(%{$self->pool_args});
}
=head2 _build_balancer
Lazy builder for the L</balancer> attribute. This takes a Pool object so that
the balancer knows which pool it's balancing.
=cut
sub _build_balancer {
my $self = shift @_;
$self->create_balancer(
pool=>$self->pool,
master=>$self->master,
%{$self->balancer_args},
);
}
=head2 _build_write_handler
Lazy builder for the L</write_handler> attribute. The default is to set this to
the L</master>.
=cut
sub _build_write_handler {
return shift->master;
}
=head2 _build_read_handler
Lazy builder for the L</read_handler> attribute. The default is to set this to
the L</balancer>.
=cut
sub _build_read_handler {
return shift->balancer;
}
=head2 around: connect_replicants
All calls to connect_replicants needs to have an existing $schema tacked onto
top of the args, since L<DBIx::Storage::DBI> needs it, and any C<connect_info>
options merged with the master, with replicant opts having higher priority.
=cut
around connect_replicants => sub {
my ($next, $self, @args) = @_;
for my $r (@args) {
$r = [ $r ] unless reftype $r eq 'ARRAY';
$self->throw_exception('coderef replicant connect_info not supported')
if ref $r->[0] && reftype $r->[0] eq 'CODE';
# any connect_info options?
my $i = 0;
$i++ while $i < @$r && (reftype($r->[$i])||'') ne 'HASH';
# make one if none
$r->[$i] = {} unless $r->[$i];
# merge if two hashes
my @hashes = @$r[$i .. $#{$r}];
$self->throw_exception('invalid connect_info options')
if (grep { reftype($_) eq 'HASH' } @hashes) != @hashes;
$self->throw_exception('too many hashrefs in connect_info')
if @hashes > 2;
my $merge = Hash::Merge->new('LEFT_PRECEDENT');
my %opts = %{ $merge->merge(reverse @hashes) };
# delete them
splice @$r, $i+1, ($#{$r} - $i), ();
# make sure master/replicants opts don't clash
my %master_opts = %{ $self->_master_connect_info_opts };
if (exists $opts{dbh_maker}) {
delete @master_opts{qw/dsn user password/};
}
delete $master_opts{dbh_maker};
# merge with master
%opts = %{ $merge->merge(\%opts, \%master_opts) };
# update
$r->[$i] = \%opts;
}
$self->$next($self->schema, @args);
};
=head2 all_storages
Returns an array of of all the connected storage backends. The first element
in the returned array is the master, and the remainings are each of the
replicants.
=cut
sub all_storages {
my $self = shift @_;
return grep {defined $_ && blessed $_} (
$self->master,
values %{ $self->replicants },
);
}
=head2 execute_reliably ($coderef, ?@args)
Given a coderef, saves the current state of the L</read_handler>, forces it to
use reliable storage (e.g. sets it to the master), executes a coderef and then
restores the original state.
Example:
my $reliably = sub {
my $name = shift @_;
$schema->resultset('User')->create({name=>$name});
my $user_rs = $schema->resultset('User')->find({name=>$name});
return $user_rs;
};
my $user_rs = $schema->storage->execute_reliably($reliably, 'John');
Use this when you must be certain of your database state, such as when you just
inserted something and need to get a resultset including it, etc.
=cut
sub execute_reliably {
my $self = shift;
my $coderef = shift;
unless( ref $coderef eq 'CODE') {
$self->throw_exception('Second argument must be a coderef');
}
## replace the current read handler for the remainder of the scope
local $self->{read_handler} = $self->master;
my $args = \@_;
return try {
$coderef->(@$args);
} catch {
$self->throw_exception("coderef returned an error: $_");
};
}
=head2 set_reliable_storage
Sets the current $schema to be 'reliable', that is all queries, both read and
write are sent to the master
=cut
sub set_reliable_storage {
my $self = shift @_;
my $schema = $self->schema;
my $write_handler = $self->schema->storage->write_handler;
$schema->storage->read_handler($write_handler);
}
=head2 set_balanced_storage
Sets the current $schema to be use the </balancer> for all reads, while all
writes are sent to the master only
=cut
sub set_balanced_storage {
my $self = shift @_;
my $schema = $self->schema;
my $balanced_handler = $self->schema->storage->balancer;
$schema->storage->read_handler($balanced_handler);
}
=head2 connected
Check that the master and at least one of the replicants is connected.
=cut
sub connected {
my $self = shift @_;
return
$self->master->connected &&
$self->pool->connected_replicants;
}
=head2 ensure_connected
Make sure all the storages are connected.
=cut
sub ensure_connected {
my $self = shift @_;
foreach my $source ($self->all_storages) {
$source->ensure_connected(@_);
}
}
=head2 limit_dialect
Set the limit_dialect for all existing storages
=cut
sub limit_dialect {
my $self = shift @_;
foreach my $source ($self->all_storages) {
$source->limit_dialect(@_);
}
return $self->master->limit_dialect;
}
=head2 quote_char
Set the quote_char for all existing storages
=cut
sub quote_char {
my $self = shift @_;
foreach my $source ($self->all_storages) {
$source->quote_char(@_);
}
return $self->master->quote_char;
}
=head2 name_sep
Set the name_sep for all existing storages
=cut
sub name_sep {
my $self = shift @_;
foreach my $source ($self->all_storages) {
$source->name_sep(@_);
}
return $self->master->name_sep;
}
=head2 set_schema
Set the schema object for all existing storages
=cut
sub set_schema {
my $self = shift @_;
foreach my $source ($self->all_storages) {
$source->set_schema(@_);
}
}
=head2 debug
set a debug flag across all storages
=cut
sub debug {
my $self = shift @_;
if(@_) {
foreach my $source ($self->all_storages) {
$source->debug(@_);
}
}
return $self->master->debug;
}
=head2 debugobj
set a debug object
=cut
sub debugobj {
my $self = shift @_;
return $self->master->debugobj(@_);
}
=head2 debugfh
set a debugfh object
=cut
sub debugfh {
my $self = shift @_;
return $self->master->debugfh(@_);
}
=head2 debugcb
set a debug callback
=cut
sub debugcb {
my $self = shift @_;
return $self->master->debugcb(@_);
}
=head2 disconnect
disconnect everything
=cut
sub disconnect {
my $self = shift @_;
foreach my $source ($self->all_storages) {
$source->disconnect(@_);
}
}
=head2 cursor_class
set cursor class on all storages, or return master's
=cut
sub cursor_class {
my ($self, $cursor_class) = @_;
if ($cursor_class) {
$_->cursor_class($cursor_class) for $self->all_storages;
}
$self->master->cursor_class;
}
=head2 cursor
set cursor class on all storages, or return master's, alias for L</cursor_class>
above.
=cut
sub cursor {
my ($self, $cursor_class) = @_;
if ($cursor_class) {
$_->cursor($cursor_class) for $self->all_storages;
}
$self->master->cursor;
}
=head2 unsafe
sets the L<DBIx::Class::Storage::DBI/unsafe> option on all storages or returns
master's current setting
=cut
sub unsafe {
my $self = shift;
if (@_) {
$_->unsafe(@_) for $self->all_storages;
}
return $self->master->unsafe;
}
=head2 disable_sth_caching
sets the L<DBIx::Class::Storage::DBI/disable_sth_caching> option on all storages
or returns master's current setting
=cut
sub disable_sth_caching {
my $self = shift;
if (@_) {
$_->disable_sth_caching(@_) for $self->all_storages;
}
return $self->master->disable_sth_caching;
}
=head2 lag_behind_master
returns the highest Replicant L<DBIx::Class::Storage::DBI/lag_behind_master>
setting
=cut
sub lag_behind_master {
my $self = shift;
return max map $_->lag_behind_master, $self->replicants;
}
=head2 is_replicating
returns true if all replicants return true for
L<DBIx::Class::Storage::DBI/is_replicating>
=cut
sub is_replicating {
my $self = shift;
return (grep $_->is_replicating, $self->replicants) == ($self->replicants);
}
=head2 connect_call_datetime_setup
calls L<DBIx::Class::Storage::DBI/connect_call_datetime_setup> for all storages
=cut
sub connect_call_datetime_setup {
my $self = shift;
$_->connect_call_datetime_setup for $self->all_storages;
}
sub _populate_dbh {
my $self = shift;
$_->_populate_dbh for $self->all_storages;
}
sub _connect {
my $self = shift;
$_->_connect for $self->all_storages;
}
sub _rebless {
my $self = shift;
$_->_rebless for $self->all_storages;
}
sub _determine_driver {
my $self = shift;
$_->_determine_driver for $self->all_storages;
}
sub _driver_determined {
my $self = shift;
if (@_) {
$_->_driver_determined(@_) for $self->all_storages;
}
return $self->master->_driver_determined;
}
sub _init {
my $self = shift;
$_->_init for $self->all_storages;
}
sub _run_connection_actions {
my $self = shift;
$_->_run_connection_actions for $self->all_storages;
}
sub _do_connection_actions {
my $self = shift;
if (@_) {
$_->_do_connection_actions(@_) for $self->all_storages;
}
}
sub connect_call_do_sql {
my $self = shift;
$_->connect_call_do_sql(@_) for $self->all_storages;
}
sub disconnect_call_do_sql {
my $self = shift;
$_->disconnect_call_do_sql(@_) for $self->all_storages;
}
sub _seems_connected {
my $self = shift;
return min map $_->_seems_connected, $self->all_storages;
}
sub _ping {
my $self = shift;
return min map $_->_ping, $self->all_storages;
}
# not using the normalized_version, because we want to preserve
# version numbers much longer than the conventional xxx.yyyzzz
my $numify_ver = sub {
my $ver = shift;
my @numparts = split /\D+/, $ver;
my $format = '%d.' . (join '', ('%06d') x (@numparts - 1));
return sprintf $format, @numparts;
};
sub _server_info {
my $self = shift;
if (not $self->_dbh_details->{info}) {
$self->_dbh_details->{info} = (
reduce { $a->[0] < $b->[0] ? $a : $b }
map [ $numify_ver->($_->{dbms_version}), $_ ],
map $_->_server_info, $self->all_storages
)->[1];
}
return $self->next::method;
}
sub _get_server_version {
my $self = shift;
return $self->_server_info->{dbms_version};
}
=head1 GOTCHAS
Due to the fact that replicants can lag behind a master, you must take care to
make sure you use one of the methods to force read queries to a master should
you need realtime data integrity. For example, if you insert a row, and then
immediately re-read it from the database (say, by doing $row->discard_changes)
or you insert a row and then immediately build a query that expects that row
to be an item, you should force the master to handle reads. Otherwise, due to
the lag, there is no certainty your data will be in the expected state.
For data integrity, all transactions automatically use the master storage for
all read and write queries. Using a transaction is the preferred and recommended
method to force the master to handle all read queries.
Otherwise, you can force a single query to use the master with the 'force_pool'
attribute:
my $row = $resultset->search(undef, {force_pool=>'master'})->find($pk);
This attribute will safely be ignore by non replicated storages, so you can use
the same code for both types of systems.
Lastly, you can use the L</execute_reliably> method, which works very much like
a transaction.
For debugging, you can turn replication on/off with the methods L</set_reliable_storage>
and L</set_balanced_storage>, however this operates at a global level and is not
suitable if you have a shared Schema object being used by multiple processes,
such as on a web application server. You can get around this limitation by
using the Schema clone method.
my $new_schema = $schema->clone;
$new_schema->set_reliable_storage;
## $new_schema will use only the Master storage for all reads/writes while
## the $schema object will use replicated storage.
=head1 AUTHOR
John Napiorkowski <john.napiorkowski@takkle.com>
Based on code originated by:
Norbert Csongrádi <bert@cpan.org>
Peter Siklósi <einon@einon.hu>
=head1 LICENSE
You may distribute this code under the same terms as Perl itself.
=cut
__PACKAGE__->meta->make_immutable;
1;