Which of the following is NOT a key feature of MongoDB?

The key feature that is not associated with MongoDB is its support for Object-Relational Mapping (ORM). MongoDB is a NoSQL database known for its flexible data model, allowing developers to use schema-less data structures, which leads to greater agility in application development. It efficiently handles large volumes of unstructured or semi-structured data without the constraints of traditional relational databases.

Additionally, MongoDB provides high availability through replica sets, which ensure that multiple copies of data are maintained for reliability and failover capabilities. It also supports horizontal scalability through sharding, enabling data to be distributed across multiple servers, effectively managing increased load and improving performance.

In contrast, ORM tools are typically tied to relational databases, which use fixed schemas and structured query language (SQL). While there are libraries available that facilitate integration between MongoDB and application code, they do not represent a core feature of MongoDB itself, but rather an adaptation to work with its data model. Thus, the absence of direct ORM support in MongoDB differentiates it from traditional SQL-based systems and highlights its unique approach to data management.