Interview Questions.

Question 1. What Is The Basic Difference Between Mysql And Mongodb?

Answer :

MySQL and MongoDB are both free and open supply databases.

MySQL and MongoDB have lots of primary variations in terms of facts illustration, querying, relationships, transactions, schema design and definition, normalization, speed and performance.

By evaluating MySQL with MongoDB, we're comparing Relational and non-relational databases.

Question 2. How Do You Compare Mongodb With Couchdb And Couchbase?

Answer :

MongoDB and CouchDB are both file-orientated databases. MongoDB and CouchDB are the pleasant examples of open supply NoSQL database.
Aside from both storing files though, it seems that they do not proportion plenty in common.
There are a whole lot of distinction between MongoDB and CouchDB in phrases of implementation in their records-model, interface, item storage, replication techniques etc.
RDBMS Interview Questions
Question 3. What Makes Mongodb Best?

Answer :

Following capabilities of MongoDB make it exceptional NoSQL database:

Document-oriented
High overall performance
High availability
Eazy scalability
Rich question language
Question four. What Is 32 Bit Nuances?

Answer :

There is greater memory mapped report interest with journaling. This will further constrain the confined db length of 32 bit builds. Thus, for now journaling by way of default is disabled on 32 bit structures.

Core Java Tutorial
Question 5. Will The Journal Replay Have Problems If Entries Are Incomplete (like The Failure Happened In The Middle Of One)?

Answer :

Each journal (organization) write is constant and might not be replayed at some stage in restoration except it's miles complete.

Core Java Interview Questions
Question 6. What Is Role Of Profiler In Mongodb?

Answer :

MongoDB consists of a database profiler which indicates performance traits of every operation towards the database. Using the profiler you may locate queries (and write operations) which might be slower than they need to be; use this statistics, for example, to decide when an index is needed.

Question 7. If You Remove An Object Attribute Is It Deleted From The Store?

Answer :

Yes, you cast off the attribute and then re-keep() the item.

SQL Database Tutorial SQL Database Interview Questions
Question eight. Can I Use The Journaling Feature To Perform Safe Hot Backups?

Answer :

Yes

Question nine. Are Null Values Allowed?

Answer :

For contributors of an item, sure. You cannot upload null to a database series even though as null isn't always an object. You can add , though.

Database Interview Questions
Question 10. Does An Update Fsync To Disk Immediately?

Answer :

No, writes to disk are lazy by means of default. A write may also hit disk more than one seconds later.

For instance: if the database receives a thousand increments to an item within one 2nd, it's going to best be flushed to disk as soon as. (Note rsync options are available though each on the command line and via getLastError old.)

Hibernate Tutorial
Question 11. How Do I Do Transactions/locking?

Answer :

MongoDB does not use conventional locking or complicated transactions with rollback, as it's miles designed to be light-weight and rapid and predictable in its performance.

It may be thought of as analogous to the MySQL MyISAM autocommit model. By maintaining transaction guide extremely easy, overall performance is enhanced, particularly in a gadget which can run throughout many servers.

Hibernate Interview Questions
Question 12. Why Are My Data Files So Large?

Answer :

MongoDB does aggressive preallocation of reserved area to avoid record system fragmentation.

RDBMS Interview Questions
Question thirteen. How Long Does Replica Set Failover Take?

Answer :

It may take 10-30 seconds for the primary to be declared down via the alternative members and a brand new number one elected.

During this window of time, the cluster is down for "primary" operations – this is, writes and robust regular reads. However, you can execute ultimately consistent queries to secondaries at any time (in slaveOk mode), including at some point of this window.

Javascript Advanced Tutorial
Question 14. What's A Master Or Primary?

Answer :

This is a node/member that is currently the number one and strategies all writes for the replica set. In a replica set, on a failover event, a unique member can become primary.

Question 15. What's A Secondary Or Slave?

Answer :

A secondary is a node/member which applies operations from the modern-day primary. This is performed by tailing the replication oplog (neighborhood.Oplog.Rs).

Replication from primary to secondary is asynchronous, however the secondary will try and stay as near current as viable (regularly that is just a few milliseconds on a LAN).

Database Design Interview Questions
Question sixteen. Should I Start Out With Sharded Or With A Non-sharded Mongodb Environment?

Answer :

We endorse beginning unsharded for simplicity and short startup unless your preliminary information set will not match on unmarried servers.

Upgrading to sharding from unsharded is straightforward and seamless, so there is not plenty of gain to putting in place sharding earlier than your facts set is large.

Software Development Lifecycle (SDLC) Tutorial
Question 17. How Does Sharding Work With Replication?

Answer :

Each shard is a logical collection of partitioned information. The shard may want to include a single server or a cluster of replicas. We advocate the use of a replica set for each shard.

Database Administration Interview Questions
Question 18. What Happens If I Try To Update A Document On A Chunk That Is Being Migrated?

Answer :

The update will go through without delay on the vintage shard, and then the change might be replicated to the brand new shard before possession transfers.

Core Java Interview Questions
Question 19. What If A Shard Is Down Or Slow And I Do A Query?

Answer :

If a shard is down, the query will return an blunders except the "Partial" question alternatives is set. If a shard is responding slowly, mongos will look ahead to it.

MongoDB Tutorial