Is MongoDB consistent or available?

MongoDB is consistent by default: reads and writes are issued to the primary member of a replica set. Applications can optionally read from secondary replicas, where data is eventually consistent by default.

Why can’t we satisfy all three properties of CAP theorem?

CAP theorem states that it is impossible to achieve all of the three properties in your Data-Stores. Here ALL three properties refer to C = Consistency, A = Availability and P = Partition Tolerance. According to this theorem it is only possible to achieve either of two at a time.

Is MongoDB a cap?

According to the CAP theorem, MongoDB is a CP system and Cassandra is an AP system.

How MongoDB provides high availability?

Replica sets use elections to support high availability. Elections occur when the primary becomes unavailable and the replica set members autonomously select a new primary. A rollback reverts write operations on a former primary when the member rejoins the replica set after a failover.

Which is not satisfied by Mongodb in CAP theorem?

Mongodb never allows write to secondary. It allows optional reads from secondary but not writes. So if your primary goes down, you can’t write till a secondary becomes primary again. That is how, you sacrifice High Availability in CAP theorem.

What is availability in MongoDB?

Availability: MongoDB gets high availability through Replica-Sets. As soon as the primary goes down or gets unavailable else, then the secondaries will determine a new primary to become available again.

Which sorting is not supported in MongoDB?

Explanation: MongoDB does not support collation-based sorting and is limited to byte-wise comparison via memcmp.

What is the CAP theorem?

CAP theorem (Brewer’s theorem) The theory proposes that when a network has been partitioned to ensure that a network failure will not prevent communication between servers, the distributed system must choose between consistency or availability.

What is NoSQL and CAP theorem?

Consistency: Every read receives the most recent write or an error

Availability: Every request receives a (non-error) response,without the guarantee that it contains the most recent write

Partition tolerance: The system continues to operate despite an arbitrary number of messages being dropped (or delayed) by the network between nodes

What is MongoDB University?

MongoDB is a free and open-source cross-platform document-oriented database program. Classified as a NoSQL database program, MongoDB uses JSON-like documents with schemata.