NAME
DBD::Multi - Manage Multiple Data Sources with Failover and Load
Balancing
SYNOPSIS
use DBI;
my $dbh = DBI->connect( 'dbi:Multi:', undef, undef, {
dsns => [ # in priority order
10 => [ 'dbi:SQLite:read_one.db', '', '' ],
10 => [ 'dbi:SQLite:read_two.db', '', '' ],
20 => [ 'dbi:SQLite:master.db', '', '' ],
],
# optional
failed_max => 1, # short credibility
failed_expire => 60*60, # long memory
});
DESCRIPTION
This software manages multiple database connections for the purposes of
load balancing and simple failover procedures. It acts as a proxy
between your code and your available databases.
Although there is some code intended for read/write operations, this
should be considered EXPIREMENTAL. This module is primary intended for
read-only operations (where some other application is being used to
handle replication).
The interface is nearly the same as other DBI drivers with one notable
exception.
Configuring DSNs
Specify an attribute to the "connect()" constructor, "dsns". This is a
list of DSNs to configure. The configuration is given in pairs. First
comes the priority of the DSN, lowest is tried first. Second is the DSN.
The second parameter can either be a DBI object or a list of parameters
to pass to the DBI "connect()" instructor.
Configuring Failures
By default a data source will not be tried again after it has failed
three times. After five minutes that failure status will be removed and
the data source may be tried again for future requests.
To change the maximum number of failures allowed before a data source is
deemed failed, set the "failed_max" parameter. To change the amount of
time we remember a data source as being failed, set the "failed_expire"
parameter in seconds.
SEE ALSO
DBD::Multiplex, DBI, perl.
AUTHOR
Initially written by Casey West and Dan Wright for pair Networks, Inc. (www.pair.com)
Maintained by Dan Wright for pair Networks, Inc. <
[email protected]>.
