Custom Parameters
MongoDB Custom Parameters
As mentioned in Using an a9s Data Service - Custom Parameters as an end user, an Application Developer has the opportunity to customize their Service Instance by using custom parameters.
set_cluster_parameter
The Platform Operator must allow this parameter to be configured. It can only be applied on cluster Data Service Instances starting with a9s MongoDB 7.
The parameter set_cluster_parameter corressponds to the MongoDB parameter setClusterParameter.
Currently, only the expireAfterSeconds parameter field of the changeStreamOptions cluster parameter is supported.
This parameter field controls how long MongoDB retains pre- and post-images. Pre-and post-images are the versions of a
document before and after it has been modified.
The accepted values for expireAfterSeconds are either off (it's default value) or an integer value greater or equal
to 0.
| Parameter | Default Value | Description |
|---|---|---|
expireAfterSeconds | off | Controls how long MongoDB retains pre- and post-images. When the value is set to off MongoDB uses the default retention policy (i.e, until the corresponding change stream events are removed from the oplog). Other values can only be integers greater than or equal to 0. The integer represents the retention time given in seconds. |
Be careful when configuring the expireAfterSeconds parameter field. If the value is set to low, it could affect the
replication of the cluster.
See the MongoDB documentation - changeStreamOptions for more details on this parameter.
Enable AppDynamics support
This feature is disabled by default. You can ask your Platform Operator to enable this feature for your Service Instance. When enabled, any user created in the MongoDB instance will have the required privileges as described here.
Any service binding (cf bind-service) created before AppDynamics support was enabled will have to be re-created
(execute cf unbind-service followed by cf bind-service). This is due to the fact the Cloud Foundry currently does
not support implementing logic that will automate this process.