Connection Options
Overview
In this guide, you can learn about MongoDB connection and authentication
options. You can set connection options as parameters of your
connection string to specify how your Client instance behaves while
connected to the server.
Option Name | Accepted Values | Default Value | Description |
|---|---|---|---|
appName | String | None | Specifies the application name that the Client instance sends
to the server as part of the handshake.Specifying an appName can help you use the server logs to
determine which Client instance is connected to the server. |
authMechanism | String | None | Specifies which authentication mechanism to use. If you do not
specify this option, the driver uses the default authentication
mechanism. To learn more about authentication in the
Rust driver, see the guide on Authentication Mechanisms. |
authMechanismProperties | String | None | Specifies more properties for the authentication mechanism
set in the authMechanism option. |
authSource | String | See description | Specifies the database used to authenticate. This option defaults to admin for SCRAM-based authentication mechanisms,
$external for the MONGODB-X509 mechanism, and the database name or
$external for the PLAIN mechanism. |
compressors | A comma-separated list of strings | None | Specifies compressors that the Client instance uses in the specified order.
To learn more about network compression, see the Network Compression guide. |
connectTimeoutMS | Non-negative integer | 10000 (10 seconds) | Specifies the connection timeout, in milliseconds, passed to each
underlying TCP stream when attempting to connect to the server. |
directConnection | Boolean | false | Specifies whether the Client instance directly connects to a single host
instead of discovering and connecting to all servers in the cluster. |
heartbeatFrequencyMS | Integer greater than or equal to 500 | 10000 (10 seconds) | Specifies the amount of time in milliseconds that each
monitoring thread waits between performing server checks. |
journal | Boolean | false | Requests acknowledgment that the operation propagated to the on-disk journal. |
localThresholdMS | Non-negative integer | 15 | Specifies the amount of time in milliseconds that the average
round-trip time between the driver and server can last
compared to the shortest round-trip time of all the suitable servers. A value of 0 indicates that there is no latency window, so
only the server with the lowest average round-trip time is
eligible. |
maxIdleTimeMS | Non-negative integer | 0 | Specifies the amount of time in milliseconds that a connection
can remain idle in a connection pool the server closes it. A value of 0 indicates that the client does not close idle
connections. |
maxStalenessSeconds | -1, or any integer greater than or equal to 90 | -1 | Specifies the maximum lag, in seconds, behind the primary node
that a secondary node can be to be considered for the given operation. The value of this option must be at least 90, or the
operation raises an error. A value of -1 means there is no
maximum lag. |
maxPoolSize | Non-negative integer | 10 | Specifies the maximum number of connections that the Client
instance can create in a connection pool for a given server.If you attempt an operation while the value of maxPoolSize
connections are checked out, the operation waits until an
in-progress operation finishes and the connection returns to the pool. |
minPoolSize | Non-negative integer | 0 | Specifies the minimum number of connections that are available in
a server's connection pool at a given time. If fewer than minPoolSize connections are in the pool,
the server adds connections in the background up to the value of minPoolSize. |
readConcernLevel | String | None | Specifies the default read concern for operations performed on the Client instance.
To learn more, see Read Concern in the Server manual. |
readPreference | String | primary | Specifies how the driver routes a read operation to members of a replica set.
To learn more, see Read Preference in the Server manual. |
readPreferenceTags | A list of comma-separated key-value pairs | None | Specifies which replica set members are considered for operations.
Each instance of this key is a separate tag set.
The driver checks each tag set until it finds one or more servers
with each tag in the set. |
replicaSet | String | None | Specifies the name of the replica set that the Client instance connects to. |
retryReads | Boolean | true | Specifies whether the client retries a read operation if the operation fails. |
serverSelectionTimeoutMS | Non-negative integer | 30000 (30 seconds) | Specifies the amount of time in milliseconds that the
Client instance waits when attempting to select a server for an
operation before timing out. |
tls | Boolean | false | Specifies the TLS configuration for the Client instance to use in its connections with the server.
By default, TLS is off. |
tlsAllowInvalidCertificates | Boolean | false | Specifies whether the Client instance returns an error if the
server presents an invalid certificate.We recommend that you set this option to true only in
testing environments to avoid creating vulnerabilities in your
application. |
tlsCAFile | String | See description | Specifies the path to the certificate authority (CA) file that
the Client instance uses for TLS.If you do not specify this option, the driver uses the Mozilla
root certificates from the webpki-roots crate. |
tlsCertificateKeyFile | String | None | Specifies the path to the certificate file that the Client
instance presents to the server to verify its identify.If you do not set this option, the Client instance does not
attempt to verify its identity to the server. |
tlsInsecure | Boolean | false | Specifies whether the Client instance returns an error if the
server presents an invalid certificate.We recommend that you set this option to true only in
testing environments to avoid creating vulnerabilities in your
application. |
w | Non-negative integer or string | None | Requests acknowledgment that the operation has propagated to a
specific number or variety of servers. To learn more, see Write Concern in the Server manual. |
wTimeoutMS | Non-negative integer | No timeout | Specifies a time limit, in milliseconds, for the write concern.
If an operation has not propagated to the requested level within
the time limit, the driver raises an error. |
zlibCompressionLevel | Integer between -1 and 9 (inclusive) | -1 | Specifies the level field of the zlib compression if you use that compressor.Setting a value of -1 selects the default compression level (6).Setting a value of 0 specifies no compression, and setting
a value of 9 specifies maximum compression.To learn more about network compression, see the Network Compression guide. |
To see a full list of connection options, visit the Connection String Options section of the Server manual entry on Connection Strings.