host¶

The "host" attribute specifies either a single server to connect to (as "hostname" or "hostname:port"), or else a connection string URI with a seed list of one or more servers plus connection options.

NOTE: Options specified in the connection string take precedence over options provided as constructor arguments.

Defaults to the connection string URI "mongodb://localhost:27017".

For IPv6 support, you must have a recent version of IO::Socket::IP installed. This module ships with the Perl core since v5.20.0 and is available on CPAN for older Perls.

app_name¶

This attribute specifies an application name that should be associated with this client. The application name will be communicated to the server as part of the initial connection handshake, and will appear in connection-level and operation-level diagnostics on the server generated on behalf of this client. This may be set in a connection string with the "appName" option.

The default is the empty string, which indicates a lack of an application name.

The application name must not exceed 128 bytes.

auth_mechanism¶

This attribute determines how the client authenticates with the server. Valid values are:

• NONE
• DEFAULT
• MONGODB-CR
• MONGODB-X509
• GSSAPI
• PLAIN
• SCRAM-SHA-1

If not specified, then if no username or "authSource" URI option is provided, it defaults to NONE. Otherwise, it is set to DEFAULT, which chooses SCRAM-SHA-1 if available or MONGODB-CR otherwise.

This may be set in a connection string with the "authMechanism" option.

auth_mechanism_properties¶

This is an optional hash reference of authentication mechanism specific properties. See "AUTHENTICATION" for details.

This may be set in a connection string with the "authMechanismProperties" option. If given, the value must be key/value pairs joined with a ":". Multiple pairs must be separated by a comma. If ": or "," appear in a key or value, they must be URL encoded.

bson_codec¶

An object that provides the "encode_one" and "decode_one" methods, such as from BSON. It may be initialized with a hash reference that will be coerced into a new BSON object.

If not provided, a BSON object with default values will be generated.

compressors¶

An array reference of compression type names. Currently, "zlib", "zstd" and "snappy" are supported.

zlib_compression_level¶

An integer from "-1" to 9 specifying the compression level to use when "compression" is set to "zlib".

Note: When the special value "-1" is given, the default compression level will be used.

connect_timeout_ms¶

This attribute specifies the amount of time in milliseconds to wait for a new connection to a server.

The default is 10,000 ms.

If set to a negative value, connection operations will block indefinitely until the server replies or until the operating system TCP/IP stack gives up (e.g. if the name can't resolve or there is no process listening on the target host/port).

A zero value polls the socket during connection and is thus likely to fail except when talking to a local process (and perhaps even then).

This may be set in a connection string with the "connectTimeoutMS" option.

db_name¶

Optional. If an "auth_mechanism" requires a database for authentication, this attribute will be used. Otherwise, it will be ignored. Defaults to "admin".

This may be provided in the connection string URI as a path between the authority and option parameter sections. For example, to authenticate against the "admin" database (showing a configuration option only for illustration):

    mongodb://localhost/admin?readPreference=primary

heartbeat_frequency_ms¶

The time in milliseconds (non-negative) between scans of all servers to check if they are up and update their latency. Defaults to 60,000 ms.

This may be set in a connection string with the "heartbeatFrequencyMS" option.

j¶

If true, the client will block until write operations have been committed to the server's journal. Prior to MongoDB 2.6, this option was ignored if the server was running without journaling. Starting with MongoDB 2.6, write operations will fail if this option is used when the server is running without journaling.

This may be set in a connection string with the "journal" option as the strings 'true' or 'false'.

local_threshold_ms¶

The width of the 'latency window': when choosing between multiple suitable servers for an operation, the acceptable delta in milliseconds (non-negative) between shortest and longest average round-trip times. Servers within the latency window are selected randomly.

Set this to "0" to always select the server with the shortest average round trip time. Set this to a very high value to always randomly choose any known server.

Defaults to 15 ms.

See "SERVER SELECTION" for more details.

This may be set in a connection string with the "localThresholdMS" option.

max_staleness_seconds¶

The "max_staleness_seconds" parameter represents the maximum replication lag in seconds (wall clock time) that a secondary can suffer and still be eligible for reads. The default is -1, which disables staleness checks. Otherwise, it must be a positive integer.

Note: this will only be used for server versions 3.4 or greater, as that was when support for staleness tracking was added.

If the read preference mode is 'primary', then "max_staleness_seconds" must not be supplied.

The "max_staleness_seconds" must be at least the "heartbeat_frequency_ms" plus 10 seconds (which is how often the server makes idle writes to the oplog).

This may be set in a connection string with the "maxStalenessSeconds" option.

max_time_ms¶

Specifies the maximum amount of time in (non-negative) milliseconds that the server should use for working on a database command. Defaults to 0, which disables this feature. Make sure this value is shorter than "socket_timeout_ms".

Note: this will only be used for server versions 2.6 or greater, as that was when the $maxTimeMS meta-operator was introduced.

You are strongly encouraged to set this variable if you know your environment has MongoDB 2.6 or later, as getting a definitive error response from the server is vastly preferred over a getting a network socket timeout.

This may be set in a connection string with the "maxTimeMS" option.

monitoring_callback¶

Specifies a code reference used to receive monitoring events. See MongoDB::Monitoring for more details.

password¶

If an "auth_mechanism" requires a password, this attribute will be used. Otherwise, it will be ignored.

This may be provided in the connection string URI as a "username:password" pair in the leading portion of the authority section before a "@" character. For example, to authenticate as user "mulder" with password "trustno1":

    mongodb://mulder:trustno1@localhost

If the username or password have a ":" or "@" in it, they must be URL encoded. An empty password still requires a ":" character.

port¶

If a network port is not specified as part of the "host" attribute, this attribute provides the port to use. It defaults to 27107.

read_concern_level¶

The read concern level determines the consistency level required of data being read.

The default level is "undef", which means the server will use its configured default.

If the level is set to "local", reads will return the latest data a server has locally.

Additional levels are storage engine specific. See Read Concern <http://docs.mongodb.org/manual/search/?query=readConcern> in the MongoDB documentation for more details.

This may be set in a connection string with the the "readConcernLevel" option.

read_pref_mode¶

The read preference mode determines which server types are candidates for a read operation. Valid values are:

• primary
• primaryPreferred
• secondary
• secondaryPreferred
• nearest

For core documentation on read preference see <http://docs.mongodb.org/manual/core/read-preference/>.

This may be set in a connection string with the "readPreference" option.

read_pref_tag_sets¶

The "read_pref_tag_sets" parameter is an ordered list of tag sets used to restrict the eligibility of servers, such as for data center awareness. It must be an array reference of hash references.

The application of "read_pref_tag_sets" varies depending on the "read_pref_mode" parameter. If the "read_pref_mode" is 'primary', then "read_pref_tag_sets" must not be supplied.

For core documentation on read preference see <http://docs.mongodb.org/manual/core/read-preference/>.

This may be set in a connection string with the "readPreferenceTags" option. If given, the value must be key/value pairs joined with a ":". Multiple pairs must be separated by a comma. If ": or "," appear in a key or value, they must be URL encoded. The "readPreferenceTags" option may appear more than once, in which case each document will be added to the tag set list.

replica_set_name¶

Specifies the replica set name to connect to. If this string is non-empty, then the topology is treated as a replica set and all server replica set names must match this or they will be removed from the topology.

This may be set in a connection string with the "replicaSet" option.

retry_reads¶

retry_writes¶

Whether the client should use retryable writes for supported commands. The default value is true, which means that commands which support retryable writes will be retried on certain errors, such as "not master" and "node is recovering" errors.

This may be set in a connection string with the "retryWrites" option.

Note that this is only supported on MongoDB > 3.6 in Replica Set or Shard Clusters, and will be ignored on other deployments.

Unacknowledged write operations also do not support retryable writes, even when retry_writes has been enabled.

The supported single statement write operations are currently as follows:

• "insert_one"
• "update_one"
• "replace_one"
• "delete_one"
• "find_one_and_delete"
• "find_one_and_replace"
• "find_one_and_update"

The supported multi statement write operations are as follows:

• "insert_many"
• "bulk_write"

The multi statement operations may be ether ordered or unordered. Note that for "bulk_write" operations, the request may not include update_many or delete_many operations.

server_selection_timeout_ms¶

This attribute specifies the amount of time in milliseconds to wait for a suitable server to be available for a read or write operation. If no server is available within this time period, an exception will be thrown.

The default is 30,000 ms.

See "SERVER SELECTION" for more details.

This may be set in a connection string with the "serverSelectionTimeoutMS" option.

server_selection_try_once¶

This attribute controls whether the client will make only a single attempt to find a suitable server for a read or write operation. The default is true.

When true, the client will not use the "server_selection_timeout_ms". Instead, if the topology information is stale and needs to be checked or if no suitable server is available, the client will make a single scan of all known servers to try to find a suitable one.

When false, the client will continually scan known servers until a suitable server is found or the "serverSelectionTimeoutMS" is reached.

See "SERVER SELECTION" for more details.

This may be set in a connection string with the "serverSelectionTryOnce" option.

server_selector¶

Optional. This takes a function that augments the server selection rules. The function takes as a parameter a list of server descriptions representing the suitable servers for the read or write operation, and returns a list of server descriptions that should still be considered suitable. Most users should rely on the default server selection algorithm and should not need to set this attribute.

socket_check_interval_ms¶

If a socket to a server has not been used in this many milliseconds, an "ismaster" command will be issued to check the status of the server before issuing any reads or writes. Must be non-negative.

The default is 5,000 ms.

This may be set in a connection string with the "socketCheckIntervalMS" option.

socket_timeout_ms¶

This attribute specifies the amount of time in milliseconds to wait for a reply from the server before issuing a network exception.

The default is 30,000 ms.

If set to a negative value, socket operations will block indefinitely until the server replies or until the operating system TCP/IP stack gives up.

The driver automatically sets the TCP keepalive option when initializing the socket. For keepalive related issues, check the MongoDB documentation for Does TCP keepalive time affect MongoDB Deployments? <https://docs.mongodb.com/v3.2/faq/diagnostics/#does-tcp-keepalive-time-affect-mongodb-deployments>.

A zero value polls the socket for available data and is thus likely to fail except when talking to a local process (and perhaps even then).

This may be set in a connection string with the "socketTimeoutMS" option.

ssl¶

    ssl => 1
    ssl => \%ssl_options

This tells the driver that you are connecting to an SSL mongodb instance.

You must have IO::Socket::SSL 1.42+ and Net::SSLeay 1.49+ installed for SSL support.

The "ssl" attribute takes either a boolean value or a hash reference of options to pass to IO::Socket::SSL. For example, to set a CA file to validate the server certificate and set a client certificate for the server to validate, you could set the attribute like this:

    ssl => {
        SSL_ca_file   => "/path/to/ca.pem",
        SSL_cert_file => "/path/to/client.pem",
    }

If "SSL_ca_file" is not provided, server certificates are verified against a default list of CAs, either Mozilla::CA or an operating-system-specific default CA file. To disable verification, you can use "SSL_verify_mode => 0x00".

You are strongly encouraged to use your own CA file for increased security.

Server hostnames are also validated against the CN name in the server certificate using "SSL_verifycn_scheme => 'http'". You can use the scheme 'none' to disable this check.

Disabling certificate or hostname verification is a security risk and is not recommended.

This may be set to the string 'true' or 'false' in a connection string with the "ssl" option, which will enable ssl with default configuration. (See connection string URI for additional TLS configuration options.)

username¶

Optional username for this client connection. If this field is set, the client will attempt to authenticate when connecting to servers. Depending on the "auth_mechanism", the "password" field or other attributes will need to be set for authentication to succeed.

This may be provided in the connection string URI as a "username:password" pair in the leading portion of the authority section before a "@" character. For example, to authenticate as user "mulder" with password "trustno1":

    mongodb://mulder:trustno1@localhost

If the username or password have a ":" or "@" in it, they must be URL encoded. An empty password still requires a ":" character.

w¶

The client write concern.

• 0 Unacknowledged. MongoClient will NOT wait for an acknowledgment that the server has received and processed the request. Older documentation may refer to this as "fire-and-forget" mode. This option is not recommended.
• 1 Acknowledged. MongoClient will wait until the primary MongoDB acknowledges the write.
• 2 Replica acknowledged. MongoClient will wait until at least two replicas (primary and one secondary) acknowledge the write. You can set a higher number for more replicas.
• "all" All replicas acknowledged.
• "majority" A majority of replicas acknowledged.

If not set, the server default is used, which is typically "1".

In MongoDB v2.0+, you can "tag" replica members. With "tagging" you can specify a custom write concern For more information see Data Center Awareness <http://docs.mongodb.org/manual/data-center-awareness/>

This may be set in a connection string with the "w" option.

wtimeout¶

The number of milliseconds an operation should wait for "w" secondaries to replicate it.

Defaults to 1000 (1 second). If you set this to undef, it could block indefinitely (or until socket timeout is reached).

See "w" above for more information.

This may be set in a connection string with the "wTimeoutMS" option.

read_preference¶

Returns a MongoDB::ReadPreference object constructed from "read_pref_mode" and "read_pref_tag_sets"

The use of "read_preference" as a mutator has been removed. Read preference is read-only. If you need a different read preference for a database or collection, you can specify that in "get_database" or "get_collection".

write_concern¶

Returns a MongoDB::WriteConcern object constructed from "w", "write_concern" and "j".

read_concern¶

Returns a MongoDB::ReadConcern object constructed from "read_concern_level".

topology_type¶

Returns an enumerated topology type. If the "replica_set_name" is set, the value will be either 'ReplicaSetWithPrimary' or 'ReplicaSetNoPrimary' (if the primary is down or not yet discovered). Without "replica_set_name", if there is more than one server in the list of hosts, the type will be 'Sharded'.

With only a single host and no replica set name, the topology type will start as 'Direct' until the server is contacted the first time, after which the type will be 'Sharded' for a mongos or 'Single' for standalone server or direct connection to a replica set member.

connect¶

    $client->connect;

Calling this method is unnecessary, as connections are established automatically as needed. It is kept for backwards compatibility. Calling it will check all servers in the deployment which ensures a connection to any that are available.

See "reconnect" for a method that is useful when using forks or threads.

disconnect¶

    $client->disconnect;

Drops all connections to servers.

reconnect¶

    $client->reconnect;

This method closes all connections to the server, as if "disconnect" were called, and then immediately reconnects. It also clears the session cache. Use this after forking or spawning off a new thread.

topology_status¶

    $client->topology_status;
    $client->topology_status( refresh => 1 );

Returns a hash reference with server topology information like this:

    {
        'topology_type' => 'ReplicaSetWithPrimary'
        'replica_set_name' => 'foo',
        'last_scan_time'   => '1433766895.183241',
        'servers'          => [
            {
                'address'     => 'localhost:50003',
                'ewma_rtt_ms' => '0.223462326',
                'type'        => 'RSSecondary'
            },
            {
                'address'     => 'localhost:50437',
                'ewma_rtt_ms' => '0.268435456',
                'type'        => 'RSArbiter'
            },
            {
                'address'     => 'localhost:50829',
                'ewma_rtt_ms' => '0.737782272',
                'type'        => 'RSPrimary'
            }
        },
    }

If the 'refresh' argument is true, then the topology will be scanned to update server data before returning the hash reference.

start_session¶

    $client->start_session;
    $client->start_session( $options );

Returns a new MongoDB::ClientSession with the supplied options.

will throw a "MongoDB::ConfigurationError" if sessions are not supported by the connected MongoDB deployment.

the options hash is an optional hash which can have the following keys:

•

"causalConsistency" - Enable Causally Consistent reads for this session. Defaults to true.

for more information see "options" in MongoDB::ClientSession.

list_databases¶

    # get all information on all databases
    my @dbs = $client->list_databases;
    # get only the foo databases
    my @foo_dbs = $client->list_databases({ filter => { name => qr/^foo/ } });

Lists all databases with information on each database. Supports filtering by any of the output fields under the "filter" argument, such as:

• "name"
• "sizeOnDisk"
• "empty"
• "shards"

database_names¶

    my @dbs = $client->database_names;
    # get only the foo database names
    my @foo_dbs = $client->database_names({ filter => { name => qr/^foo/ } });

List of all database names on the MongoDB server. Supports filters in the same way as "list_databases".

get_database, db¶

    my $database = $client->get_database('foo');
    my $database = $client->get_database('foo', $options);
    my $database = $client->db('foo', $options);

Returns a MongoDB::Database instance for the database with the given $name.

It takes an optional hash reference of options that are passed to the MongoDB::Database constructor.

The "db" method is an alias for "get_database".

get_namespace, ns¶

    my $collection = $client->get_namespace('test.foo');
    my $collection = $client->get_namespace('test.foo', $options);
    my $collection = $client->ns('test.foo', $options);

Returns a MongoDB::Collection instance for the given namespace. The namespace has both the database name and the collection name separated with a dot character.

This is a quick way to get a collection object if you don't need the database object separately.

It takes an optional hash reference of options that are passed to the MongoDB::Collection constructor. The intermediate MongoDB::Database object will be created with default options.

The "ns" method is an alias for "get_namespace".

fsync(\%args)¶

    $client->fsync();

A function that will forces the server to flush all pending writes to the storage layer.

The fsync operation is synchronous by default, to run fsync asynchronously, use the following form:

    $client->fsync({async => 1});

The primary use of fsync is to lock the database during backup operations. This will flush all data to the data storage layer and block all write operations until you unlock the database. Note: you can still read while the database is locked.

    $conn->fsync({lock => 1});

fsync_unlock¶

    $conn->fsync_unlock();

Unlocks a database server to allow writes and reverses the operation of a $conn->fsync({lock => 1}); operation.

watch¶

Watches for changes on the cluster.

Perform an aggregation with an implicit initial $changeStream stage and returns a MongoDB::ChangeStream result which can be used to iterate over the changes in the cluster. This functionality is available since MongoDB 4.0.

    my $stream = $client->watch();
    my $stream = $client->watch( \@pipeline );
    my $stream = $client->watch( \@pipeline, \%options );
    while (1) {
        # This inner loop will only run until no more changes are
        # available.
        while (my $change = $stream->next) {
            # process $change
        }
    }

The returned stream will not block forever waiting for changes. If you want to respond to changes over a longer time use "maxAwaitTimeMS" and regularly call "next" in a loop.

See "watch" in MongoDB::Collection for details on usage and available options.

MONGODB-CR and SCRAM-SHA-1 (for username/password)¶

These mechanisms require a username and password, given either as constructor attributes or in the "host" connection string.

If a username is provided and an authentication mechanism is not specified, the client will use SCRAM-SHA-1 for version 3.0 or later servers and will fall back to MONGODB-CR for older servers.

    my $mc = MongoDB::MongoClient->new(
        host => "mongodb://mongo.example.com/",
        username => "johndoe",
        password => "trustno1",
    );
    my $mc = MongoDB::MongoClient->new(
        host => "mongodb://johndoe:trustno1@mongo.example.com/",
    );

Usernames and passwords will be UTF-8 encoded before use. The password is never sent over the wire -- only a secure digest is used. The SCRAM-SHA-1 mechanism is the Salted Challenge Response Authentication Mechanism defined in RFC 5802 <http://tools.ietf.org/html/rfc5802>.

The default database for authentication is 'admin'. If another database name should be used, specify it with the "db_name" attribute or via the connection string.

    db_name => auth_db
    mongodb://johndoe:trustno1@mongo.example.com/auth_db

MONGODB-X509 (for SSL client certificate)¶

X509 authentication requires SSL support (IO::Socket::SSL), requires that a client certificate be configured in the ssl parameters, and requires specifying the "MONGODB-X509" authentication mechanism.

    my $mc = MongoDB::MongoClient->new(
        host => "mongodb://sslmongo.example.com/",
        ssl => {
            SSL_ca_file   => "certs/ca.pem",
            SSL_cert_file => "certs/client.pem",
        },
        auth_mechanism => "MONGODB-X509",
    );

Note: Since MongoDB Perl driver v1.8.0, you no longer need to specify a "username" parameter for X509 authentication; the username will be extracted automatically from the certificate.

PLAIN (for LDAP)¶

This mechanism requires a username and password, which will be UTF-8 encoded before use. The "auth_mechanism" parameter must be given as a constructor attribute or in the "host" connection string:

    my $mc = MongoDB::MongoClient->new(
        host => "mongodb://mongo.example.com/",
        username => "johndoe",
        password => "trustno1",
        auth_mechanism => "PLAIN",
    );
    my $mc = MongoDB::MongoClient->new(
        host => "mongodb://johndoe:trustno1@mongo.example.com/authMechanism=PLAIN",
    );

GSSAPI (for Kerberos)¶

Kerberos authentication requires the CPAN module Authen::SASL and a GSSAPI-capable backend.

On Debian systems, Authen::SASL may be available as "libauthen-sasl-perl"; on RHEL systems, it may be available as "perl-Authen-SASL".

The Authen::SASL::Perl backend comes with Authen::SASL and requires the GSSAPI CPAN module for GSSAPI support. On Debian systems, this may be available as "libgssapi-perl"; on RHEL systems, it may be available as "perl-GSSAPI".

Installing the GSSAPI module from CPAN rather than an OS package requires "libkrb5" and the "krb5-config" utility (available for Debian/RHEL systems in the "libkrb5-dev" package).

Alternatively, the Authen::SASL::XS or Authen::SASL::Cyrus modules may be used. Both rely on Cyrus "libsasl". Authen::SASL::XS is preferred, but not yet available as an OS package. Authen::SASL::Cyrus is available on Debian as "libauthen-sasl-cyrus-perl" and on RHEL as "perl-Authen-SASL-Cyrus".

Installing Authen::SASL::XS or Authen::SASL::Cyrus from CPAN requires "libsasl". On Debian systems, it is available from "libsasl2-dev"; on RHEL, it is available in "cyrus-sasl-devel".

To use the GSSAPI mechanism, first run "kinit" to authenticate with the ticket granting service:

    $ kinit johndoe@EXAMPLE.COM

Configure MongoDB::MongoClient with the principal name as the "username" parameter and specify 'GSSAPI' as the "auth_mechanism":

    my $mc = MongoDB::MongoClient->new(
        host => 'mongodb://mongo.example.com',
        username => 'johndoe@EXAMPLE.COM',
        auth_mechanism => 'GSSAPI',
    );

Both can be specified in the "host" connection string, keeping in mind that the '@' in the principal name must be encoded as "%40":

    my $mc = MongoDB::MongoClient->new(
        host =>
          'mongodb://johndoe%40EXAMPLE.COM@mongo.example.com/?authMechanism=GSSAPI',
    );

The default service name is 'mongodb'. It can be changed with the "auth_mechanism_properties" attribute or in the connection string.

    auth_mechanism_properties => { SERVICE_NAME => 'other_service' }
    mongodb://.../?authMechanism=GSSAPI&authMechanismProperties=SERVICE_NAME:other_service