1MongoDB::MongoClient(3)User Contributed Perl DocumentatioMnongoDB::MongoClient(3)
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3
4

NAME

6       MongoDB::MongoClient - A connection to a MongoDB server or multi-server
7       deployment
8

VERSION

10       version v2.2.2
11

SYNOPSIS

13           use MongoDB; # also loads MongoDB::MongoClient
14
15           # connect to localhost:27017
16           my $client = MongoDB::MongoClient->new;
17
18           # connect to specific host and port
19           my $client = MongoDB::MongoClient->new(
20               host => "mongodb://mongo.example.com:27017"
21           );
22
23           # connect to a replica set (set name *required*)
24           my $client = MongoDB::MongoClient->new(
25               host => "mongodb://mongo1.example.com,mongo2.example.com",
26               replica_set_name => 'myset',
27           );
28
29           # connect to a replica set with URI (set name *required*)
30           my $client = MongoDB::MongoClient->new(
31               host => "mongodb://mongo1.example.com,mongo2.example.com/?replicaSet=myset",
32           );
33
34           my $db = $client->get_database("test");
35           my $coll = $db->get_collection("people");
36
37           $coll->insert({ name => "John Doe", age => 42 });
38           my @people = $coll->find()->all();
39

DESCRIPTION

41       The "MongoDB::MongoClient" class represents a client connection to one
42       or more MongoDB servers.
43
44       By default, it connects to a single server running on the local machine
45       listening on the default port 27017:
46
47           # connects to localhost:27017
48           my $client = MongoDB::MongoClient->new;
49
50       It can connect to a database server running anywhere, though:
51
52           my $client = MongoDB::MongoClient->new(host => 'example.com:12345');
53
54       See the "host" attribute for more options for connecting to MongoDB.
55
56       MongoDB can be started in authentication mode
57       <http://docs.mongodb.org/manual/core/authentication/>, which requires
58       clients to log in before manipulating data.  By default, MongoDB does
59       not start in this mode, so no username or password is required to make
60       a fully functional connection.  To configure the client for
61       authentication, see the "AUTHENTICATION" section.
62
63       The actual socket connections are lazy and created on demand.  When the
64       client object goes out of scope, all socket will be closed.  Note that
65       MongoDB::Database, MongoDB::Collection and related classes could hold a
66       reference to the client as well.  Only when all references are out of
67       scope will the sockets be closed.
68

ATTRIBUTES

70   host
71       The "host" attribute specifies either a single server to connect to (as
72       "hostname" or "hostname:port"), or else a connection string URI with a
73       seed list of one or more servers plus connection options.
74
75       NOTE: Options specified in the connection string take precedence over
76       options provided as constructor arguments.
77
78       Defaults to the connection string URI "mongodb://localhost:27017".
79
80       For IPv6 support, you must have a recent version of IO::Socket::IP
81       installed.  This module ships with the Perl core since v5.20.0 and is
82       available on CPAN for older Perls.
83
84   app_name
85       This attribute specifies an application name that should be associated
86       with this client.  The application name will be communicated to the
87       server as part of the initial connection handshake, and will appear in
88       connection-level and operation-level diagnostics on the server
89       generated on behalf of this client.  This may be set in a connection
90       string with the "appName" option.
91
92       The default is the empty string, which indicates a lack of an
93       application name.
94
95       The application name must not exceed 128 bytes.
96
97   auth_mechanism
98       This attribute determines how the client authenticates with the server.
99       Valid values are:
100
101       •   NONE
102
103       •   DEFAULT
104
105       •   MONGODB-CR
106
107       •   MONGODB-X509
108
109       •   GSSAPI
110
111       •   PLAIN
112
113       •   SCRAM-SHA-1
114
115       If not specified, then if no username or "authSource" URI option is
116       provided, it defaults to NONE.  Otherwise, it is set to DEFAULT, which
117       chooses SCRAM-SHA-1 if available or MONGODB-CR otherwise.
118
119       This may be set in a connection string with the "authMechanism" option.
120
121   auth_mechanism_properties
122       This is an optional hash reference of authentication mechanism specific
123       properties.  See "AUTHENTICATION" for details.
124
125       This may be set in a connection string with the
126       "authMechanismProperties" option.  If given, the value must be
127       key/value pairs joined with a ":".  Multiple pairs must be separated by
128       a comma.  If ": or "," appear in a key or value, they must be URL
129       encoded.
130
131   bson_codec
132       An object that provides the "encode_one" and "decode_one" methods, such
133       as from BSON.  It may be initialized with a hash reference that will be
134       coerced into a new BSON object.
135
136       If not provided, a BSON object with default values will be generated.
137
138   compressors
139       An array reference of compression type names. Currently, "zlib", "zstd"
140       and "snappy" are supported.
141
142   zlib_compression_level
143       An integer from "-1" to 9 specifying the compression level to use when
144       "compression" is set to "zlib".
145
146       Note: When the special value "-1" is given, the default compression
147       level will be used.
148
149   connect_timeout_ms
150       This attribute specifies the amount of time in milliseconds to wait for
151       a new connection to a server.
152
153       The default is 10,000 ms.
154
155       If set to a negative value, connection operations will block
156       indefinitely until the server replies or until the operating system
157       TCP/IP stack gives up (e.g. if the name can't resolve or there is no
158       process listening on the target host/port).
159
160       A zero value polls the socket during connection and is thus likely to
161       fail except when talking to a local process (and perhaps even then).
162
163       This may be set in a connection string with the "connectTimeoutMS"
164       option.
165
166   db_name
167       Optional.  If an "auth_mechanism" requires a database for
168       authentication, this attribute will be used.  Otherwise, it will be
169       ignored. Defaults to "admin".
170
171       This may be provided in the connection string URI as a path between the
172       authority and option parameter sections.  For example, to authenticate
173       against the "admin" database (showing a configuration option only for
174       illustration):
175
176           mongodb://localhost/admin?readPreference=primary
177
178   heartbeat_frequency_ms
179       The time in milliseconds (non-negative) between scans of all servers to
180       check if they are up and update their latency.  Defaults to 60,000 ms.
181
182       This may be set in a connection string with the "heartbeatFrequencyMS"
183       option.
184
185   j
186       If true, the client will block until write operations have been
187       committed to the server's journal. Prior to MongoDB 2.6, this option
188       was ignored if the server was running without journaling. Starting with
189       MongoDB 2.6, write operations will fail if this option is used when the
190       server is running without journaling.
191
192       This may be set in a connection string with the "journal" option as the
193       strings 'true' or 'false'.
194
195   local_threshold_ms
196       The width of the 'latency window': when choosing between multiple
197       suitable servers for an operation, the acceptable delta in milliseconds
198       (non-negative) between shortest and longest average round-trip times.
199       Servers within the latency window are selected randomly.
200
201       Set this to "0" to always select the server with the shortest average
202       round trip time.  Set this to a very high value to always randomly
203       choose any known server.
204
205       Defaults to 15 ms.
206
207       See "SERVER SELECTION" for more details.
208
209       This may be set in a connection string with the "localThresholdMS"
210       option.
211
212   max_staleness_seconds
213       The "max_staleness_seconds" parameter represents the maximum
214       replication lag in seconds (wall clock time) that a secondary can
215       suffer and still be eligible for reads. The default is -1, which
216       disables staleness checks.  Otherwise, it must be a positive integer.
217
218       Note: this will only be used for server versions 3.4 or greater, as
219       that was when support for staleness tracking was added.
220
221       If the read preference mode is 'primary', then "max_staleness_seconds"
222       must not be supplied.
223
224       The "max_staleness_seconds" must be at least the
225       "heartbeat_frequency_ms" plus 10 seconds (which is how often the server
226       makes idle writes to the oplog).
227
228       This may be set in a connection string with the "maxStalenessSeconds"
229       option.
230
231   max_time_ms
232       Specifies the maximum amount of time in (non-negative) milliseconds
233       that the server should use for working on a database command.  Defaults
234       to 0, which disables this feature.  Make sure this value is shorter
235       than "socket_timeout_ms".
236
237       Note: this will only be used for server versions 2.6 or greater, as
238       that was when the $maxTimeMS meta-operator was introduced.
239
240       You are strongly encouraged to set this variable if you know your
241       environment has MongoDB 2.6 or later, as getting a definitive error
242       response from the server is vastly preferred over a getting a network
243       socket timeout.
244
245       This may be set in a connection string with the "maxTimeMS" option.
246
247   monitoring_callback
248       Specifies a code reference used to receive monitoring events.  See
249       MongoDB::Monitoring for more details.
250
251   password
252       If an "auth_mechanism" requires a password, this attribute will be
253       used.  Otherwise, it will be ignored.
254
255       This may be provided in the connection string URI as a
256       "username:password" pair in the leading portion of the authority
257       section before a "@" character.  For example, to authenticate as user
258       "mulder" with password "trustno1":
259
260           mongodb://mulder:trustno1@localhost
261
262       If the username or password have a ":" or "@" in it, they must be URL
263       encoded.  An empty password still requires a ":" character.
264
265   port
266       If a network port is not specified as part of the "host" attribute,
267       this attribute provides the port to use.  It defaults to 27107.
268
269   read_concern_level
270       The read concern level determines the consistency level required of
271       data being read.
272
273       The default level is "undef", which means the server will use its
274       configured default.
275
276       If the level is set to "local", reads will return the latest data a
277       server has locally.
278
279       Additional levels are storage engine specific.  See Read Concern
280       <http://docs.mongodb.org/manual/search/?query=readConcern> in the
281       MongoDB documentation for more details.
282
283       This may be set in a connection string with the the "readConcernLevel"
284       option.
285
286   read_pref_mode
287       The read preference mode determines which server types are candidates
288       for a read operation.  Valid values are:
289
290       •   primary
291
292       •   primaryPreferred
293
294       •   secondary
295
296       •   secondaryPreferred
297
298       •   nearest
299
300       For core documentation on read preference see
301       <http://docs.mongodb.org/manual/core/read-preference/>.
302
303       This may be set in a connection string with the "readPreference"
304       option.
305
306   read_pref_tag_sets
307       The "read_pref_tag_sets" parameter is an ordered list of tag sets used
308       to restrict the eligibility of servers, such as for data center
309       awareness.  It must be an array reference of hash references.
310
311       The application of "read_pref_tag_sets" varies depending on the
312       "read_pref_mode" parameter.  If the "read_pref_mode" is 'primary', then
313       "read_pref_tag_sets" must not be supplied.
314
315       For core documentation on read preference see
316       <http://docs.mongodb.org/manual/core/read-preference/>.
317
318       This may be set in a connection string with the "readPreferenceTags"
319       option.  If given, the value must be key/value pairs joined with a ":".
320       Multiple pairs must be separated by a comma.  If ": or "," appear in a
321       key or value, they must be URL encoded.  The "readPreferenceTags"
322       option may appear more than once, in which case each document will be
323       added to the tag set list.
324
325   replica_set_name
326       Specifies the replica set name to connect to.  If this string is non-
327       empty, then the topology is treated as a replica set and all server
328       replica set names must match this or they will be removed from the
329       topology.
330
331       This may be set in a connection string with the "replicaSet" option.
332
333   retry_reads
334   retry_writes
335       Whether the client should use retryable writes for supported commands.
336       The default value is true, which means that commands which support
337       retryable writes will be retried on certain errors, such as "not
338       master" and "node is recovering" errors.
339
340       This may be set in a connection string with the "retryWrites" option.
341
342       Note that this is only supported on MongoDB > 3.6 in Replica Set or
343       Shard Clusters, and will be ignored on other deployments.
344
345       Unacknowledged write operations also do not support retryable writes,
346       even when retry_writes has been enabled.
347
348       The supported single statement write operations are currently as
349       follows:
350
351       •   "insert_one"
352
353       •   "update_one"
354
355       •   "replace_one"
356
357       •   "delete_one"
358
359       •   "find_one_and_delete"
360
361       •   "find_one_and_replace"
362
363       •   "find_one_and_update"
364
365       The supported multi statement write operations are as follows:
366
367       •   "insert_many"
368
369       •   "bulk_write"
370
371       The multi statement operations may be ether ordered or unordered. Note
372       that for "bulk_write" operations, the request may not include
373       update_many or delete_many operations.
374
375   server_selection_timeout_ms
376       This attribute specifies the amount of time in milliseconds to wait for
377       a suitable server to be available for a read or write operation.  If no
378       server is available within this time period, an exception will be
379       thrown.
380
381       The default is 30,000 ms.
382
383       See "SERVER SELECTION" for more details.
384
385       This may be set in a connection string with the
386       "serverSelectionTimeoutMS" option.
387
388   server_selection_try_once
389       This attribute controls whether the client will make only a single
390       attempt to find a suitable server for a read or write operation.  The
391       default is true.
392
393       When true, the client will not use the "server_selection_timeout_ms".
394       Instead, if the topology information is stale and needs to be checked
395       or if no suitable server is available, the client will make a single
396       scan of all known servers to try to find a suitable one.
397
398       When false, the client will continually scan known servers until a
399       suitable server is found or the "serverSelectionTimeoutMS" is reached.
400
401       See "SERVER SELECTION" for more details.
402
403       This may be set in a connection string with the
404       "serverSelectionTryOnce" option.
405
406   server_selector
407       Optional. This takes a function that augments the server selection
408       rules.  The function takes as a parameter a list of server descriptions
409       representing the suitable servers for the read or write operation, and
410       returns a list of server descriptions that should still be considered
411       suitable. Most users should rely on the default server selection
412       algorithm and should not need to set this attribute.
413
414   socket_check_interval_ms
415       If a socket to a server has not been used in this many milliseconds, an
416       "ismaster" command will be issued to check the status of the server
417       before issuing any reads or writes. Must be non-negative.
418
419       The default is 5,000 ms.
420
421       This may be set in a connection string with the "socketCheckIntervalMS"
422       option.
423
424   socket_timeout_ms
425       This attribute specifies the amount of time in milliseconds to wait for
426       a reply from the server before issuing a network exception.
427
428       The default is 30,000 ms.
429
430       If set to a negative value, socket operations will block indefinitely
431       until the server replies or until the operating system TCP/IP stack
432       gives up.
433
434       The driver automatically sets the TCP keepalive option when
435       initializing the socket. For keepalive related issues, check the
436       MongoDB documentation for Does TCP keepalive time affect MongoDB
437       Deployments? <https://docs.mongodb.com/v3.2/faq/diagnostics/#does-tcp-
438       keepalive-time-affect-mongodb-deployments>.
439
440       A zero value polls the socket for available data and is thus likely to
441       fail except when talking to a local process (and perhaps even then).
442
443       This may be set in a connection string with the "socketTimeoutMS"
444       option.
445
446   ssl
447           ssl => 1
448           ssl => \%ssl_options
449
450       This tells the driver that you are connecting to an SSL mongodb
451       instance.
452
453       You must have IO::Socket::SSL 1.42+ and Net::SSLeay 1.49+ installed for
454       SSL support.
455
456       The "ssl" attribute takes either a boolean value or a hash reference of
457       options to pass to IO::Socket::SSL.  For example, to set a CA file to
458       validate the server certificate and set a client certificate for the
459       server to validate, you could set the attribute like this:
460
461           ssl => {
462               SSL_ca_file   => "/path/to/ca.pem",
463               SSL_cert_file => "/path/to/client.pem",
464           }
465
466       If "SSL_ca_file" is not provided, server certificates are verified
467       against a default list of CAs, either Mozilla::CA or an operating-
468       system-specific default CA file.  To disable verification, you can use
469       "SSL_verify_mode => 0x00".
470
471       You are strongly encouraged to use your own CA file for increased
472       security.
473
474       Server hostnames are also validated against the CN name in the server
475       certificate using "SSL_verifycn_scheme => 'http'".  You can use the
476       scheme 'none' to disable this check.
477
478       Disabling certificate or hostname verification is a security risk and
479       is not recommended.
480
481       This may be set to the string 'true' or 'false' in a connection string
482       with the "ssl" option, which will enable ssl with default
483       configuration.  (See connection string URI for additional TLS
484       configuration options.)
485
486   username
487       Optional username for this client connection.  If this field is set,
488       the client will attempt to authenticate when connecting to servers.
489       Depending on the "auth_mechanism", the "password" field or other
490       attributes will need to be set for authentication to succeed.
491
492       This may be provided in the connection string URI as a
493       "username:password" pair in the leading portion of the authority
494       section before a "@" character.  For example, to authenticate as user
495       "mulder" with password "trustno1":
496
497           mongodb://mulder:trustno1@localhost
498
499       If the username or password have a ":" or "@" in it, they must be URL
500       encoded.  An empty password still requires a ":" character.
501
502   w
503       The client write concern.
504
505       •   0 Unacknowledged. MongoClient will NOT wait for an acknowledgment
506           that the server has received and processed the request. Older
507           documentation may refer to this as "fire-and-forget" mode.  This
508           option is not recommended.
509
510       •   1 Acknowledged. MongoClient will wait until the primary MongoDB
511           acknowledges the write.
512
513       •   2 Replica acknowledged. MongoClient will wait until at least two
514           replicas (primary and one secondary) acknowledge the write. You can
515           set a higher number for more replicas.
516
517       •   "all" All replicas acknowledged.
518
519       •   "majority" A majority of replicas acknowledged.
520
521       If not set, the server default is used, which is typically "1".
522
523       In MongoDB v2.0+, you can "tag" replica members. With "tagging" you can
524       specify a custom write concern For more information see Data Center
525       Awareness <http://docs.mongodb.org/manual/data-center-awareness/>
526
527       This may be set in a connection string with the "w" option.
528
529   wtimeout
530       The number of milliseconds an operation should wait for "w" secondaries
531       to replicate it.
532
533       Defaults to 1000 (1 second). If you set this to undef, it could block
534       indefinitely (or until socket timeout is reached).
535
536       See "w" above for more information.
537
538       This may be set in a connection string with the "wTimeoutMS" option.
539

METHODS

541   read_preference
542       Returns a MongoDB::ReadPreference object constructed from
543       "read_pref_mode" and "read_pref_tag_sets"
544
545       The use of "read_preference" as a mutator has been removed.  Read
546       preference is read-only.  If you need a different read preference for a
547       database or collection, you can specify that in "get_database" or
548       "get_collection".
549
550   write_concern
551       Returns a MongoDB::WriteConcern object constructed from "w",
552       "write_concern" and "j".
553
554   read_concern
555       Returns a MongoDB::ReadConcern object constructed from
556       "read_concern_level".
557
558   topology_type
559       Returns an enumerated topology type.  If the "replica_set_name" is set,
560       the value will be either 'ReplicaSetWithPrimary' or
561       'ReplicaSetNoPrimary' (if the primary is down or not yet discovered).
562       Without "replica_set_name", if there is more than one server in the
563       list of hosts, the type will be 'Sharded'.
564
565       With only a single host and no replica set name, the topology type will
566       start as 'Direct' until the server is contacted the first time, after
567       which the type will be 'Sharded' for a mongos or 'Single' for
568       standalone server or direct connection to a replica set member.
569
570   connect
571           $client->connect;
572
573       Calling this method is unnecessary, as connections are established
574       automatically as needed.  It is kept for backwards compatibility.
575       Calling it will check all servers in the deployment which ensures a
576       connection to any that are available.
577
578       See "reconnect" for a method that is useful when using forks or
579       threads.
580
581   disconnect
582           $client->disconnect;
583
584       Drops all connections to servers.
585
586   reconnect
587           $client->reconnect;
588
589       This method closes all connections to the server, as if "disconnect"
590       were called, and then immediately reconnects.  It also clears the
591       session cache.  Use this after forking or spawning off a new thread.
592
593   topology_status
594           $client->topology_status;
595           $client->topology_status( refresh => 1 );
596
597       Returns a hash reference with server topology information like this:
598
599           {
600               'topology_type' => 'ReplicaSetWithPrimary'
601               'replica_set_name' => 'foo',
602               'last_scan_time'   => '1433766895.183241',
603               'servers'          => [
604                   {
605                       'address'     => 'localhost:50003',
606                       'ewma_rtt_ms' => '0.223462326',
607                       'type'        => 'RSSecondary'
608                   },
609                   {
610                       'address'     => 'localhost:50437',
611                       'ewma_rtt_ms' => '0.268435456',
612                       'type'        => 'RSArbiter'
613                   },
614                   {
615                       'address'     => 'localhost:50829',
616                       'ewma_rtt_ms' => '0.737782272',
617                       'type'        => 'RSPrimary'
618                   }
619               },
620           }
621
622       If the 'refresh' argument is true, then the topology will be scanned to
623       update server data before returning the hash reference.
624
625   start_session
626           $client->start_session;
627           $client->start_session( $options );
628
629       Returns a new MongoDB::ClientSession with the supplied options.
630
631       will throw a "MongoDB::ConfigurationError" if sessions are not
632       supported by the connected MongoDB deployment.
633
634       the options hash is an optional hash which can have the following keys:
635
636       •   "causalConsistency" - Enable Causally Consistent reads for this
637           session. Defaults to true.
638
639       for more information see "options" in MongoDB::ClientSession.
640
641   list_databases
642           # get all information on all databases
643           my @dbs = $client->list_databases;
644
645           # get only the foo databases
646           my @foo_dbs = $client->list_databases({ filter => { name => qr/^foo/ } });
647
648       Lists all databases with information on each database. Supports
649       filtering by any of the output fields under the "filter" argument, such
650       as:
651
652       •   "name"
653
654       •   "sizeOnDisk"
655
656       •   "empty"
657
658       •   "shards"
659
660   database_names
661           my @dbs = $client->database_names;
662
663           # get only the foo database names
664           my @foo_dbs = $client->database_names({ filter => { name => qr/^foo/ } });
665
666       List of all database names on the MongoDB server. Supports filters in
667       the same way as "list_databases".
668
669   get_database, db
670           my $database = $client->get_database('foo');
671           my $database = $client->get_database('foo', $options);
672           my $database = $client->db('foo', $options);
673
674       Returns a MongoDB::Database instance for the database with the given
675       $name.
676
677       It takes an optional hash reference of options that are passed to the
678       MongoDB::Database constructor.
679
680       The "db" method is an alias for "get_database".
681
682   get_namespace, ns
683           my $collection = $client->get_namespace('test.foo');
684           my $collection = $client->get_namespace('test.foo', $options);
685           my $collection = $client->ns('test.foo', $options);
686
687       Returns a MongoDB::Collection instance for the given namespace.  The
688       namespace has both the database name and the collection name separated
689       with a dot character.
690
691       This is a quick way to get a collection object if you don't need the
692       database object separately.
693
694       It takes an optional hash reference of options that are passed to the
695       MongoDB::Collection constructor.  The intermediate MongoDB::Database
696       object will be created with default options.
697
698       The "ns" method is an alias for "get_namespace".
699
700   fsync(\%args)
701           $client->fsync();
702
703       A function that will forces the server to flush all pending writes to
704       the storage layer.
705
706       The fsync operation is synchronous by default, to run fsync
707       asynchronously, use the following form:
708
709           $client->fsync({async => 1});
710
711       The primary use of fsync is to lock the database during backup
712       operations. This will flush all data to the data storage layer and
713       block all write operations until you unlock the database. Note: you can
714       still read while the database is locked.
715
716           $conn->fsync({lock => 1});
717
718   fsync_unlock
719           $conn->fsync_unlock();
720
721       Unlocks a database server to allow writes and reverses the operation of
722       a $conn->fsync({lock => 1}); operation.
723
724   watch
725       Watches for changes on the cluster.
726
727       Perform an aggregation with an implicit initial $changeStream stage and
728       returns a MongoDB::ChangeStream result which can be used to iterate
729       over the changes in the cluster. This functionality is available since
730       MongoDB 4.0.
731
732           my $stream = $client->watch();
733           my $stream = $client->watch( \@pipeline );
734           my $stream = $client->watch( \@pipeline, \%options );
735
736           while (1) {
737
738               # This inner loop will only run until no more changes are
739               # available.
740               while (my $change = $stream->next) {
741                   # process $change
742               }
743           }
744
745       The returned stream will not block forever waiting for changes. If you
746       want to respond to changes over a longer time use "maxAwaitTimeMS" and
747       regularly call "next" in a loop.
748
749       See "watch" in MongoDB::Collection for details on usage and available
750       options.
751

DEPLOYMENT TOPOLOGY

753       MongoDB can operate as a single server or as a distributed system.  One
754       or more servers that collectively provide access to a single logical
755       set of MongoDB databases are referred to as a "deployment".
756
757       There are three types of deployments:
758
759       •   Single server – a stand-alone mongod database
760
761       •   Replica set – a set of mongod databases with data replication and
762           fail-over capability
763
764       •   Sharded cluster – a distributed deployment that spreads data across
765           one or more shards, each of which can be a replica set.  Clients
766           communicate with a mongos process that routes operations to the
767           correct share.
768
769       The state of a deployment, including its type, which servers are
770       members, the server types of members and the round-trip network latency
771       to members is referred to as the "topology" of the deployment.
772
773       To the greatest extent possible, the MongoDB driver abstracts away the
774       details of communicating with different deployment types.  It
775       determines the deployment topology through a combination of the
776       connection string, configuration options and direct discovery
777       communicating with servers in the deployment.
778

CONNECTION STRING URI

780       MongoDB uses a pseudo-URI connection string to specify one or more
781       servers to connect to, along with configuration options.
782
783       NOTE: any non-printable ASCII characters should be UTF-8 encoded and
784       converted URL-escaped characters.
785
786       To connect to more than one database server, provide host or host:port
787       pairs as a comma separated list:
788
789           mongodb://host1[:port1][,host2[:port2],...[,hostN[:portN]]]
790
791       This list is referred to as the "seed list".  An arbitrary number of
792       hosts can be specified.  If a port is not specified for a given host,
793       it will default to 27017.
794
795       If multiple hosts are given in the seed list or discovered by talking
796       to servers in the seed list, they must all be replica set members or
797       must all be mongos servers for a sharded cluster.
798
799       A replica set MUST have the "replicaSet" option set to the replica set
800       name.
801
802       If there is only single host in the seed list and "replicaSet" is not
803       provided, the deployment is treated as a single server deployment and
804       all reads and writes will be sent to that host.
805
806       Providing a replica set member as a single host without the set name is
807       the way to get a "direct connection" for carrying out administrative
808       activities on that server.
809
810       The connection string may also have a username and password:
811
812           mongodb://username:password@host1:port1,host2:port2
813
814       The username and password must be URL-escaped.
815
816       A optional database name for authentication may be given:
817
818           mongodb://username:password@host1:port1,host2:port2/my_database
819
820       Finally, connection string options may be given as URI attribute pairs
821       in a query string:
822
823           mongodb://host1:port1,host2:port2/?ssl=1&wtimeoutMS=1000
824           mongodb://username:password@host1:port1,host2:port2/my_database?ssl=1&wtimeoutMS=1000
825
826       The currently supported connection string options are:
827
828       •   "appName"
829
830       •   "authMechanism"
831
832       •   "authMechanismProperties"
833
834       •   "authSource"
835
836       •   "compressors"
837
838       •   "connect"
839
840       •   "connectTimeoutMS"
841
842       •   "heartbeatFrequencyMS"
843
844       •   "journal"
845
846       •   "localThresholdMS"
847
848       •   "maxStalenessSeconds"
849
850       •   "maxTimeMS"
851
852       •   "readConcernLevel"
853
854       •   "readPreference"
855
856       •   "readPreferenceTags"
857
858       •   "replicaSet"
859
860       •   "retryReads"
861
862       •   "retryWrites"
863
864       •   "serverSelectionTimeoutMS"
865
866       •   "serverSelectionTryOnce"
867
868       •   "socketCheckIntervalMS"
869
870       •   "socketTimeoutMS"
871
872       •   "ssl"
873
874       •   "tls" (an alias for "ssl")
875
876       •   "tlsAllowInvalidCertificates"
877
878       •   "tlsAllowInvalidHostnames"
879
880       •   "tlsCAFile"
881
882       •   "tlsCertificateKeyFile"
883
884       •   "tlsCertificateKeyFilePassword"
885
886       •   "tlsInsecure"
887
888       •   "w"
889
890       •   "wTimeoutMS"
891
892       •   "zlibCompressionLevel"
893
894       NOTE: Options specified in the connection string take precedence over
895       options provided as constructor arguments.
896
897       See the official MongoDB documentation on connection strings for more
898       on the URI format and connection string options:
899       <http://docs.mongodb.org/manual/reference/connection-string/>.
900

SERVER SELECTION

902       For a single server deployment or a direct connection to a mongod or
903       mongos, all reads and writes are sent to that server.  Any read-
904       preference is ignored.
905
906       When connected to a deployment with multiple servers, such as a replica
907       set or sharded cluster, the driver chooses a server for operations
908       based on the type of operation (read or write), application-provided
909       server selector, the types of servers available and a read preference.
910
911       For a replica set deployment, writes are sent to the primary (if
912       available) and reads are sent to a server based on the
913       "read_preference" attribute, which defaults to sending reads to the
914       primary.  See MongoDB::ReadPreference for more.
915
916       For a sharded cluster reads and writes are distributed across mongos
917       servers in the seed list.  Any read preference is passed through to the
918       mongos and used by it when executing reads against shards.
919
920       If multiple servers can service an operation (e.g. multiple mongos
921       servers, or multiple replica set members), one is chosen by filtering
922       with server selector and then at random from within the "latency
923       window".  The server with the shortest average round-trip time (RTT) is
924       always in the window.  Any servers with an average round-trip time less
925       than or equal to the shortest RTT plus the "local_threshold_ms" are
926       also in the latency window.
927
928       If a suitable server is not immediately available, what happens next
929       depends on the "server_selection_try_once" option.
930
931       If that option is true, a single topology scan will be performed.
932       Afterwards if a suitable server is available, it will be returned;
933       otherwise, an exception is thrown.
934
935       If that option is false, the driver will do topology scans repeatedly
936       looking for a suitable server.  When more than
937       "server_selection_timeout_ms" milliseconds have elapsed since the start
938       of server selection without a suitable server being found, an exception
939       is thrown.
940
941       Note: the actual maximum wait time for server selection could be as
942       long "server_selection_timeout_ms" plus the amount of time required to
943       do a topology scan.
944

SERVER MONITORING AND FAILOVER

946       When the client first needs to find a server for a database operation,
947       all servers from the "host" attribute are scanned to determine which
948       servers to monitor.  If the deployment is a replica set, additional
949       hosts may be discovered in this process.  Invalid hosts are dropped.
950
951       After the initial scan, whenever the servers have not been checked in
952       "heartbeat_frequency_ms" milliseconds, the scan will be repeated.  This
953       amortizes monitoring time over many of operations.  Additionally, if a
954       socket has been idle for a while, it will be checked before being used
955       for an operation.
956
957       If a server operation fails because of a "not master" or "node is
958       recovering" error, or if there is a network error or timeout, then the
959       server is flagged as unavailable and exception will be thrown.  See
960       MongoDB::Errors for exception types.
961
962       If the error is caught and handled, the next operation will rescan all
963       servers immediately to update its view of the topology.  The driver can
964       continue to function as long as servers are suitable per "SERVER
965       SELECTION".
966
967       When catching an exception, users must determine whether or not their
968       application should retry an operation based on the specific operation
969       attempted and other use-case-specific considerations.  For automating
970       retries despite exceptions, consider using the Try::Tiny::Retry module.
971

TRANSPORT LAYER SECURITY

973       Warning: industry best practices, and some regulations, require the use
974       of TLS 1.1 or newer.
975
976       Some operating systems or versions may not provide an OpenSSL version
977       new enough to support the latest TLS protocols.  If your OpenSSL
978       library version number is less than 1.0.1, then support for TLS 1.1 or
979       newer is not available. Contact your operating system vendor for a
980       solution or upgrade to a newer operating system distribution.
981
982       See also the documentation for Net::SSLeay for details on installing
983       and compiling against OpenSSL.
984
985       TLS connections in the driver rely on the default settings provided by
986       IO::Socket::SSL, but allow you to pass custom configuration to it.
987       Please read its documentation carefully to see how to control your TLS
988       configuration.
989

AUTHENTICATION

991       The MongoDB server provides several authentication mechanisms, though
992       some are only available in the Enterprise edition.
993
994       MongoDB client authentication is controlled via the "auth_mechanism"
995       attribute, which takes one of the following values:
996
997       NOTE: MONGODB-CR was deprecated with the release of MongoDB 3.6 and is
998       no longer supported by MongoDB 4.0.
999
1000       •   MONGODB-CR -- legacy username-password challenge-response (< 4.0)
1001
1002       •   SCRAM-SHA-1 -- secure username-password challenge-response (3.0+)
1003
1004       •   MONGODB-X509 -- SSL client certificate authentication (2.6+)
1005
1006       •   PLAIN -- LDAP authentication via SASL PLAIN (Enterprise only)
1007
1008       •   GSSAPI -- Kerberos authentication (Enterprise only)
1009
1010       The mechanism to use depends on the authentication configuration of the
1011       server.  See the core documentation on authentication:
1012       <http://docs.mongodb.org/manual/core/access-control/>.
1013
1014       Usage information for each mechanism is given below.
1015
1016   MONGODB-CR and SCRAM-SHA-1 (for username/password)
1017       These mechanisms require a username and password, given either as
1018       constructor attributes or in the "host" connection string.
1019
1020       If a username is provided and an authentication mechanism is not
1021       specified, the client will use SCRAM-SHA-1 for version 3.0 or later
1022       servers and will fall back to MONGODB-CR for older servers.
1023
1024           my $mc = MongoDB::MongoClient->new(
1025               host => "mongodb://mongo.example.com/",
1026               username => "johndoe",
1027               password => "trustno1",
1028           );
1029
1030           my $mc = MongoDB::MongoClient->new(
1031               host => "mongodb://johndoe:trustno1@mongo.example.com/",
1032           );
1033
1034       Usernames and passwords will be UTF-8 encoded before use.  The password
1035       is never sent over the wire -- only a secure digest is used.  The
1036       SCRAM-SHA-1 mechanism is the Salted Challenge Response Authentication
1037       Mechanism defined in RFC 5802 <http://tools.ietf.org/html/rfc5802>.
1038
1039       The default database for authentication is 'admin'.  If another
1040       database name should be used, specify it with the "db_name" attribute
1041       or via the connection string.
1042
1043           db_name => auth_db
1044
1045           mongodb://johndoe:trustno1@mongo.example.com/auth_db
1046
1047   MONGODB-X509 (for SSL client certificate)
1048       X509 authentication requires SSL support (IO::Socket::SSL), requires
1049       that a client certificate be configured in the ssl parameters, and
1050       requires specifying the "MONGODB-X509" authentication mechanism.
1051
1052           my $mc = MongoDB::MongoClient->new(
1053               host => "mongodb://sslmongo.example.com/",
1054               ssl => {
1055                   SSL_ca_file   => "certs/ca.pem",
1056                   SSL_cert_file => "certs/client.pem",
1057               },
1058               auth_mechanism => "MONGODB-X509",
1059           );
1060
1061       Note: Since MongoDB Perl driver v1.8.0, you no longer need to specify a
1062       "username" parameter for X509 authentication; the username will be
1063       extracted automatically from the certificate.
1064
1065   PLAIN (for LDAP)
1066       This mechanism requires a username and password, which will be UTF-8
1067       encoded before use.  The "auth_mechanism" parameter must be given as a
1068       constructor attribute or in the "host" connection string:
1069
1070           my $mc = MongoDB::MongoClient->new(
1071               host => "mongodb://mongo.example.com/",
1072               username => "johndoe",
1073               password => "trustno1",
1074               auth_mechanism => "PLAIN",
1075           );
1076
1077           my $mc = MongoDB::MongoClient->new(
1078               host => "mongodb://johndoe:trustno1@mongo.example.com/authMechanism=PLAIN",
1079           );
1080
1081   GSSAPI (for Kerberos)
1082       Kerberos authentication requires the CPAN module Authen::SASL and a
1083       GSSAPI-capable backend.
1084
1085       On Debian systems, Authen::SASL may be available as
1086       "libauthen-sasl-perl"; on RHEL systems, it may be available as
1087       "perl-Authen-SASL".
1088
1089       The Authen::SASL::Perl backend comes with Authen::SASL and requires the
1090       GSSAPI CPAN module for GSSAPI support.  On Debian systems, this may be
1091       available as "libgssapi-perl"; on RHEL systems, it may be available as
1092       "perl-GSSAPI".
1093
1094       Installing the GSSAPI module from CPAN rather than an OS package
1095       requires "libkrb5" and the "krb5-config" utility (available for
1096       Debian/RHEL systems in the "libkrb5-dev" package).
1097
1098       Alternatively, the Authen::SASL::XS or Authen::SASL::Cyrus modules may
1099       be used.  Both rely on Cyrus "libsasl".  Authen::SASL::XS is preferred,
1100       but not yet available as an OS package.  Authen::SASL::Cyrus is
1101       available on Debian as "libauthen-sasl-cyrus-perl" and on RHEL as
1102       "perl-Authen-SASL-Cyrus".
1103
1104       Installing Authen::SASL::XS or Authen::SASL::Cyrus from CPAN requires
1105       "libsasl".  On Debian systems, it is available from "libsasl2-dev"; on
1106       RHEL, it is available in "cyrus-sasl-devel".
1107
1108       To use the GSSAPI mechanism, first run "kinit" to authenticate with the
1109       ticket granting service:
1110
1111           $ kinit johndoe@EXAMPLE.COM
1112
1113       Configure MongoDB::MongoClient with the principal name as the
1114       "username" parameter and specify 'GSSAPI' as the "auth_mechanism":
1115
1116           my $mc = MongoDB::MongoClient->new(
1117               host => 'mongodb://mongo.example.com',
1118               username => 'johndoe@EXAMPLE.COM',
1119               auth_mechanism => 'GSSAPI',
1120           );
1121
1122       Both can be specified in the "host" connection string, keeping in mind
1123       that the '@' in the principal name must be encoded as "%40":
1124
1125           my $mc = MongoDB::MongoClient->new(
1126               host =>
1127                 'mongodb://johndoe%40EXAMPLE.COM@mongo.example.com/?authMechanism=GSSAPI',
1128           );
1129
1130       The default service name is 'mongodb'.  It can be changed with the
1131       "auth_mechanism_properties" attribute or in the connection string.
1132
1133           auth_mechanism_properties => { SERVICE_NAME => 'other_service' }
1134
1135           mongodb://.../?authMechanism=GSSAPI&authMechanismProperties=SERVICE_NAME:other_service
1136

THREAD-SAFETY AND FORK-SAFETY

1138       You MUST call the "reconnect" method on any MongoDB::MongoClient
1139       objects after forking or spawning a thread.
1140
1141       NOTE: Per threads documentation, use of Perl threads is discouraged by
1142       the maintainers of Perl and the MongoDB Perl driver does not test or
1143       provide support for use with threads.
1144

AUTHORS

1146       •   David Golden <david@mongodb.com>
1147
1148       •   Rassi <rassi@mongodb.com>
1149
1150       •   Mike Friedman <friedo@friedo.com>
1151
1152       •   Kristina Chodorow <k.chodorow@gmail.com>
1153
1154       •   Florian Ragwitz <rafl@debian.org>
1155
1157       This software is Copyright (c) 2020 by MongoDB, Inc.
1158
1159       This is free software, licensed under:
1160
1161         The Apache License, Version 2.0, January 2004
1162
1163
1164
1165perl v5.34.0                      2021-07-22           MongoDB::MongoClient(3)
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