How to check the active and standby nodes of current replica set instance
You can view the node information of the current instance in the DDS console, the steps are as follows:
Log in to the DDS console.
On the Instance Management page of the Management Center, click the instance ID to go to the Basic Information of the instance.
Slide to the bottom of the Basic Information page to view the node information.
Can I delete an index that fails to be created in DDS
• First, you can check the status of the index to determine whether it is in a failed state. In most document databases, you can check the index status by querying system tables or using commands.
• If the index is in a failed state, you can try to delete it. Typically, you can delete the index using the appropriate method in database management tool, command line tool, or programming language.
Does DDS support using TTL index to clean up expired data
Yes, it does.
How to use MapReduce command
Command Explanation
In DDS, MapReduce is a data processing model used to process large-scale data, and MapReduce operations can be performed through the map-reduce command.
Common error handling when the MapReduce command fails
Error message
• Max output document size exceeded: The output document size exceeds the maximum limit.
Possible Reasons
• Max output document size exceeded: The output document is too large and exceeds MongoDB's single document size limit.
Solution
• Max output document size exceeded:
– Use smaller output documents to reduce output document size by merging or grouping.
– Consider using Aggregation Pipeline instead of MapReduce, which supports larger output document size.
Does DDS support $round function
Yes, all versions after MongoDB 3.4 support the $round function.
How to manage Balancer
DDS supports Balancer management operations. In some special business scenarios, ensure the balanced distribution of data. However, you can also disable or enable Balancer by configuring parameters and specifying the operating mode of Balancer.