What is the difference between local and global writes in MongoDB?

The correct answer focuses on the fundamental distinction between local and global writes in MongoDB. Local writes are limited to a single shard, meaning that the changes made by these writes affect only the data stored on that particular shard. This is particularly relevant in a sharded cluster environment, where data is distributed across multiple shards for scalability and performance. Global writes, on the other hand, are operations that impact the entire cluster, updating data across multiple shards simultaneously.

This distinction is crucial for developers and database administrators to understand, as it influences how data consistency and transaction management are handled in a distributed system. Local writes can be advantageous in scenarios where writes need to be fast and isolated to a single shard without the overhead of coordinating across the entire cluster. Conversely, global writes are essential when operations need to ensure consistency across all parts of the data set.

The other choices do not accurately represent the relationship between local and global writes. For example, the notion that only global writes can create new documents is incorrect; both types of writes can create documents, but their scope differs. Additionally, the speed comparison made in the first option does not universally apply, as performance depends on various factors like network latency and cluster configuration. Lastly, the rollback capability mentioned in the fourth option mis