MongoDB Interview Questions and Answers
Question - 101 : - What are the substitutes for MongoDB?
Answer - 101 : -
Following are the substitutes to MongoDB:
- Hbase
- CouchDB
- Cassandra
- Redis
- Riak
Question - 102 : - How can we old files in the moveChunk directory?
Answer - 102 : -
In the course of general shard balancing operations, we make the old files as backups, and we can delete them when those operations are completed.
Question - 103 : - What is a Storage Engine?
Answer - 103 : -
Storage Engine is a component of the database that is accountable to manage how we store on the disk. For instance, one storage engine may provide better performance for the read-heavy workloads, and another one may support a great throughput for the write operations.
Question - 104 : - Does MongoDB require plenty of RAM?
Answer - 104 : -
No, MongoDB does not require plenty of RAM. It can run on a small amount of memory. MongoDB dynamically assigns and unassigns RAM according to the needs of other processes.
Question - 105 : - How do we perform the Join operations in MongoDB?
Answer - 105 : -
From MongoDB3.2, we can perform the Join operation. The new $lookup operator included with the aggregation pipeline is the same as the left outer join. Example:
{
$lookup:
{
from: ,
localField: ,
foreignField: ,
as:
}
}
Question - 106 : - What are the storage engines used by MongoDB?
Answer - 106 : -
WiredTiger and MMAPv1 are the two storage engines used by MongoDB.
Question - 107 : - How do we configure the cache size in MongoDB?
Answer - 107 : -
In MongoDB, we cannot configure the cache. MongoDB utilizes the free spaces over the system automatically by using memory-mapped files.
Question - 108 : - How do we control the MongoDB Performance?
Answer - 108 : -
We can control the MongoDB Performance by:
- Locking the Performance
- Identifying the number of connections
- Database Profiling
- Full-time Diagnostic Data Capture
Question - 109 : - What are the aggregate functions of MongoDB?
Answer - 109 : -
Following are the aggregate functions of MongoDB:
- AVG
- Sum
- Min
- Max
- First
- Push
- addTo Set
- Last