Document Database Service(aka dds) is an open source project born from HuaweiCloud's MongoDB service. The codebase is based on MongoDB-4.0.3, the latest 4.0 series which still follows AGPL license. There are several enhancements which are not supported in MongoDB community version.
As MongoDB Company does not release Auditing functionality in community version, almost all cloud providers have their own solutions for auditing. dds also provides s set of configurations for auditing. Generally, users can add lines below into mongodb's yaml configuration to enable auditing.
auditLog:
authSuccess: true|false
format: JSON
opFilter: off|all|...
path: /path/to/your/audit_log
For the details of configuring auditing parameters, please see Audit Configuration
Although MongoDB limited the memory used for wiredTiger/rocksDB engine. It sometimes may still OOM, that's because MongoDB's QueryStage does not have the global memory limit. Let's take an example, one user can use at most 32MB RAM. However, if 100 queries run the sort in parallel, that should be 3.2GB. Until Mongo4.0, there is no global limit for this. We added a suite of parameters to limit query stage memory usage in total. please see Query Memory limit Params for more details.