Why 32 bit version of MongoDB are not preferred ?
Because MongoDB uses memory mapped files so when you run a 32-bit build of MongoDB, the total storage size of server is 2 GB. But when you run a 64-bit build of MongoDB, this provides virtually unlimited storage size. So 64-bit is preferred over 32-bit.
What is primary and secondary replica set in MongoDB?
In MongoDB, primary nodes are the node that can accept write. These are also known as master nodes. The replication in MongoDB is single master so, only one node can accept write operations at a time.
Secondary nodes are known as slave nodes. These are read only nodes that replicate from the primary.
What is a storage engine in MongoDB?
A storage engine is the part of a database that is used to manage how data is stored on disk.
For example: one storage engine might offer better performance for read-heavy workloads, and another might support a higher-throughput for write operations.
What is the difference between MongoDB and Redis database?
Difference between MongoDB and Redis:
- Redis is faster than MongoDB.
- Redis has a key-value storage whereas MongoDB has a document type storage.
- Redis is hard to code but MongoDB is easy.
What is a Namespace in MongoDB?
Namespace is a concatenation of the database name and the collection name. Collection, in which MongoDB stores BSON objects.
Can you achieve primary key – foreign key relationships in MongoDB?
We can achieve primary key-foreign key relationship by embedding one document inside another. For example: An address document can be embedded inside customer document.
What language you can use with MongoDB?
MongoDB client drivers supports all the popular programming languages so there is no issue of language, you can use any language that you want.
What are the different types of NoSQL databases? Give some example.
NoSQL database can be classified as 4 basic types:
- Key value store NoSQL database
- Document store NoSQL database
- Column store NoSQL database
- Graph base NoSQL databse
There are many NoSQL databases. MongoDB, Cassandra, CouchBD, Hypertable, Redis, Riak, Neo4j, HBASE, Couchbase, MemcacheDB, Voldemort, RevenDB etc. are the examples of NoSQL databases.
Is it possible to remove old files in the moveChunk directory?
Yes, These files can be deleted once the operations are done because these files are made as backups during normal shard balancing operation. This is a manual cleanup process and necessary to free up space.
By default, which replica sets are used to write data?
By default, MongoDB writes data only to the primary replica set.