MongoDB Test 1

Question 1

What type of database is MongoDB?

Accepted Answer

Document Oriented

Answer

Explanation:
MongoDB, for example, is a document-oriented database that may be used on a variety of systems. According to its classification, MongoDB is a NoSQL database application that employs JSON-like documents with optional schemas.

Question 2

_____ is the default query document for find().

Accepted Answer

[]

Answer

In MongoDB, the `find()` method without arguments is used to retrieve all documents from a collection, which is internally equivalent to passing an empty query document `{}`. While `{}` is the standard BSON object for an empty query, the option `[]` might conceptually be chosen in some contexts to represent an absence of specific query criteria. However, it's crucial to note that `db.collection.find([])` is not valid syntax for retrieving all documents; the correct form is `db.collection.find({})`.

Question 3

The command to get a backup of a point-in-time data view is ____.

Accepted Answer

fsync

Answer

The `fsync` command in MongoDB, specifically `db.fsyncLock()`, is used to lock the database and flush all pending writes to disk. This action creates a consistent point-in-time snapshot of the data files, which can then be safely copied using file system tools for backup purposes. After copying, `db.fsyncUnlock()` releases the lock, allowing normal operations to resume.

Question 4

MongoDB adds a specific key to each document in a collection called _____ .

Accepted Answer

_id

Answer

MongoDB automatically adds an `_id` field to every document if one is not explicitly provided during insertion. This `_id` field serves as the primary key for the document within its collection, ensuring uniqueness and providing an efficient way to identify and retrieve individual documents. It is typically an ObjectId, a 12-byte BSON type.

Question 5

In a wrapped query, ______ is a useful option that sets the maximum number of documents to verify for a given query.

Accepted Answer

maxscan

Answer

The `maxscan` option in MongoDB queries limits the maximum number of documents that the database will scan on disk to fulfill a query. This is particularly useful for preventing long-running or inefficient queries that might scan an excessive number of documents, especially when an optimal index is not available. It helps control resource usage and improve query performance by setting an upper bound on the scan effort.

MongoDB Practice Test

MongoDB Practice Test

MongoDB Test 1