typedef struct _mongoc_uri_t mongoc_uri_t;


mongoc_uri_t provides an abstraction on top of the MongoDB connection URI format. It provides standardized parsing as well as convenience methods for extracting useful information such as replica hosts or authorization information.

See Connection String URI Reference on the MongoDB website for more information.


mongodb://                                   <1>
   [username:password@]                      <2>
   host1                                     <3>
   [:port1]                                  <4>
   [,host2[:port2],...[,hostN[:portN]]]      <5>
   [/[database]                              <6>
   [?options]]                               <7>
  1. mongodb is the specifier of the MongoDB protocol.

  2. An optional username and password.

  3. The only required part of the uri. This specifies either a hostname, IP address or UNIX domain socket.

  4. An optional port number. Defaults to :27017.

  5. Extra optional hosts and ports. You would specify multiple hosts, for example, for connections to replica sets.

  6. The name of the database to authenticate if the connection string includes authentication credentials. If /database is not specified and the connection string includes credentials, defaults to the 'admin' database.

  7. Connection specific options.

Replica Set Example

To describe a connection to a replica set named 'test' with the following mongod hosts:

  • on port 27017

  • on port 2500

You would use the connection string that resembles the following.


Connection Options


{true|false}, idicating if SSL must be used.


A timeout in milliseconds to attempt a connection before timing out. The default is no timeout.


The time in milliseconds to attempt to send or receive on a socket before the attempt times out. The default is 5 minutes.

Connection Pool Options


The maximum number of connections in the pool. The default value is 100.


The minimum number of connections in the connection pool. Default value is 0. These are lazily created.


Not implemented.


Not implemented.


Not implemented.

Write Concern Options



The driver will not acknowledge write operations and will suppress all network or socket errors.


The driver will not acknowledge write operations but will pass or handle any network and socket errors that it receives to the client. If you disable write concern but enable the getLastError command’s w option, w overrides the w option.


Provides basic acknowledgment of write operations. By specifying 1, you require that a standalone mongod instance, or the primary for replica sets, acknowledge all write operations. For drivers released after the default write concern change, this is the default write concern setting.


For replica sets, if you specify the special majority value to w option, write operations will only return successfully after a majority of the configured replica set members have acknowledged the write operation.


For replica sets, if you specify a number n greater than 1, operations with this write concern return only after n members of the set have acknowledged the write. If you set n to a number that is greater than the number of available set members or members that hold data, MongoDB will wait, potentially indefinitely, for these members to become available.


For replica sets, you can specify a tag set to require that all members of the set that have these tags configured return confirmation of the write operation.


The time in milliseconds to wait for replication to succeed, as specified in the w option, before timing out. When wtimeoutMS is 0, write operations will never time out.


Controls whether write operations will wait until the mongod acknowledges the write operations and commits the data to the on disk journal.


Enables journal commit acknowledgment write concern. Equivalent to specifying the getLastError command with the j option enabled.


Does not require that mongod commit write operations to the journal before acknowledging the write operation. This is the default option for the journal parameter.

Read Preference Options


Specifies the replica set read preference for this connection. This setting overrides any slaveOk value. The read preference values are the following:

  • primary

  • primaryPreferred

  • secondary

  • secondaryPreferred

  • nearest


Specifies a tag set as a comma-seperated list of colon-separted key-value pairs.