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Question 381

Which BSON type represents a 64-bit signed integer?

1. BSON Double
2. BSON Int32
3. BSON Decimal128
4. BSON Int64

Correct Answer: 4

Explanation:

BSON Int64 represents a signed 64-bit integer in MongoDB documents. It is useful when numeric values can exceed the range supported by a 32-bit integer, such as large counters, identifiers, or financial-related quantities that are represented as whole numbers. MongoDB drivers may expose this BSON type differently depending on the programming language and its native numeric capabilities. BSON Double uses floating-point representation, Int32 stores 32-bit integers, and Decimal128 provides high-precision decimal arithmetic. Choosing the appropriate numeric representation helps prevent overflow or unintended type conversions when applications exchange data with MongoDB.

Question 382

Which BSON type represents a 32-bit signed integer?

1. BSON Long
2. BSON Int32
3. BSON NumberDecimal
4. BSON Double

Correct Answer: 2

Explanation:

BSON Int32 stores signed 32-bit integer values. It is appropriate for whole numbers that fit within the range supported by a 32-bit signed integer. MongoDB drivers commonly map this BSON type to a language’s ordinary integer representation when that mapping is safe. Larger whole-number values can require Int64, while Decimal128 is designed for high-precision decimal calculations. Double represents floating-point numbers and can introduce precision characteristics that differ from integer storage. Understanding BSON numeric types is important when designing schemas and ensuring that applications handle values consistently across different programming languages.

Question 383

Which BSON type stores exact decimal floating-point values?

1. BSON Double
2. BSON Int64
3. BSON Decimal128
4. BSON Int32

Correct Answer: 3

Explanation:

BSON Decimal128 provides decimal floating-point representation with high precision. It is especially useful for values where decimal precision matters, such as monetary amounts, rates, or calculations that should avoid some of the rounding characteristics associated with binary floating-point values. MongoDB introduced Decimal128 to support applications requiring predictable decimal arithmetic. Double is a binary floating-point type, while Int32 and Int64 are integer types. Applications handling financial or precision-sensitive numeric data should choose a representation that matches their calculation requirements and ensure that their MongoDB drivers preserve the intended BSON type.

Question 384

Which BSON type stores a binary data value?

1. BSON Blob
2. BSON Binary
3. BSON Bytes
4. BSON Raw

Correct Answer: 2

Explanation:

BSON Binary stores arbitrary binary data inside a MongoDB document. It can represent application-specific binary content and uses a subtype to describe the intended binary representation. Common examples include UUID values and other binary application data. MongoDB drivers generally expose BSON Binary through language-specific APIs. BSON Binary should not be confused with BSON types such as String, Date, or ObjectId, each of which has different semantics. BSON Blob, BSON Bytes, and BSON Raw are not the standard BSON type names used by MongoDB for general binary values.

Question 385

Which BSON type represents the smallest possible BSON value?

1. MinKey
2. Null
3. Undefined
4. MaxKey

Correct Answer: 1

Explanation:

The BSON MinKey type represents a special value that compares lower than every other BSON value. It is mainly useful in internal comparisons and specialized operations rather than ordinary application data modeling. Its counterpart, MaxKey, compares higher than all other BSON values. Null represents a null value and has different comparison semantics, while Undefined is a legacy BSON type with limited modern application use. Understanding special BSON comparison types can be useful when examining sort behavior, index boundaries, or MongoDB internals.

Question 386

Which BSON type represents the greatest possible BSON value?

1. MinKey
2. MaxKey
3. Null
4. Undefined

Correct Answer: 2

Explanation:

The BSON MaxKey type represents a special value that compares higher than every other BSON value. It is primarily useful for internal comparison behavior and situations where an absolute upper boundary is required. MinKey provides the corresponding lower boundary. Null represents the absence of a value and does not have the same special maximum comparison semantics. Undefined is a legacy BSON type and should generally not be confused with MaxKey. These special BSON values can appear when examining internal database behavior, range boundaries, or sorting semantics.

Question 387

Which BSON type represents a regular expression pattern?

1. BSON Pattern
2. BSON Regex
3. BSON Expression
4. BSON Matcher

Correct Answer: 2

Explanation:

BSON Regex represents a regular expression pattern stored as a BSON value. MongoDB supports regular-expression matching for suitable string queries and aggregation expressions. A BSON regular expression includes the pattern and can include regular-expression options that influence matching behavior. Applications should consider indexing and query selectivity when using regex predicates because not every regex pattern can efficiently use an index. BSON Pattern, BSON Expression, and BSON Matcher are not the standard BSON type names for regular expressions.

Question 388

Which cursor option limits server wait time for awaited results?

1. awaitTimeoutMS
2. maxAwaitTimeMS
3. cursorWaitMS
4. serverAwaitLimit

Correct Answer: 2

Explanation:

The maxAwaitTimeMS cursor option specifies the maximum amount of time the server should wait for new data when using a tailable await cursor. It is designed for workloads where a cursor remains open and waits for additional documents, such as monitoring or certain event-streaming patterns. It differs from general connection and server-selection timeouts because it applies specifically to awaiting results from an eligible cursor. awaitTimeoutMS, cursorWaitMS, and serverAwaitLimit are not the standard MongoDB cursor option names for this behavior.

Question 389

Which cursor option requests only indexed key data?

1. returnKey
2. indexOnly
3. keyProjection
4. returnIndex

Correct Answer: 1

Explanation:

The returnKey cursor option causes MongoDB to return only the indexed key values rather than the complete documents. This can be useful when an application needs to inspect index keys or retrieve values represented by an index without requiring the full document contents. The behavior depends on an appropriate index being available for the query. indexOnly, keyProjection, and returnIndex are not the standard MongoDB cursor option names for this purpose. returnKey should also be distinguished from a covered query, which is a query execution characteristic rather than simply an option name.

Question 390

Which cursor option includes the internal record identifier?

1. showRecordId
2. includeRecordKey
3. returnRecordId
4. exposeStorageId

Correct Answer: 1

Explanation:

The showRecordId cursor option requests inclusion of the internal record identifier in returned documents. This identifier is associated with the storage engine’s internal representation and can be useful for certain diagnostic or specialized operations. It should not be confused with the document’s _id field, which is an application-visible identifier stored as part of the document. Internal record identifiers are not generally appropriate as stable application identifiers. includeRecordKey, returnRecordId, and exposeStorageId are not the standard MongoDB cursor option names for requesting this internal identifier.

Question 391

Which update operator sets a field to the smaller value?

1. $minimum
2. $min
3. $lowest
4. $smaller

Correct Answer: 2

Explanation:

The $min update operator changes a field only when the specified value is less than the field’s current value. This is useful for maintaining minimum observed values without first reading the existing document into application code. For example, an application can use $min to retain the earliest or smallest numeric value encountered. MongoDB performs the comparison and update as part of the write operation. $minimum, $lowest, and $smaller are not standard MongoDB update operators for this behavior.

Question 392

Which update operator sets a field to the larger value?

1. $maximum
2. $highest
3. $max
4. $larger

Correct Answer: 3

Explanation:

The $max update operator updates a field only when the supplied value is greater than the field’s existing value. It is useful for maintaining maximum counters, highest scores, latest numeric thresholds, or other peak measurements. Because MongoDB performs the comparison during the update, the application does not need to retrieve the current value before deciding whether to update it. $maximum, $highest, and $larger are not the standard MongoDB update operator names. $max should also be distinguished from aggregation accumulators that calculate maximum values across multiple documents.

Question 393

Which update operator removes a specified field from a document?

1. $unset
2. $deleteField
3. $removeField
4. $dropField

Correct Answer: 1

Explanation:

The $unset update operator removes a specified field from a document. It is useful when a field is obsolete, no longer applicable, or should be removed during a schema migration. The operator can be applied to selected documents using a normal update filter. Removing a field differs from assigning it the value null, because $unset eliminates the field from the document entirely. $deleteField, $removeField, and $dropField are not standard update operator names for this purpose.

Question 394

Which update operator adds a value to an array only if absent?

1. $appendUnique
2. $uniquePush
3. $insertDistinct
4. $addToSet

Correct Answer: 4

Explanation:

The $addToSet update operator adds a value to an array only when that value is not already present. It is useful when an application needs to maintain a collection of unique array elements without first checking the document in application code. For multiple values, $addToSet can be combined with $each. Unlike $push, it prevents duplicate values based on MongoDB’s comparison rules. $appendUnique, $uniquePush, and $insertDistinct are not standard MongoDB update operators. This makes $addToSet particularly useful for tags, memberships, or other unique array attributes.

Question 395

Which update modifier controls array ordering after $push?

1. $order
2. $sort
3. $arrange
4. $orderBy

Correct Answer: 2

Explanation:

The $sort modifier can be combined with $push and $each to sort array elements after new values are added. This is useful when an array must maintain a defined order automatically, such as keeping scores ranked or maintaining events in a desired sequence. $sort can be used with $slice when the application also wants to retain only a fixed number of sorted elements. $order, $arrange, and $orderBy are not the MongoDB update modifiers used for sorting array contents during a $push operation.

Question 396

Which aggregation stage counts documents matching a condition?

1. $countIf
2. $countMatch
3. $matchCount
4. $count

Correct Answer: 4

Explanation:

The $count aggregation stage counts the documents that reach that point in the pipeline and stores the resulting number in a specified field. When combined with $match, it can count documents satisfying a particular condition. For example, a pipeline can first filter records and then use $count to produce the number of matching documents. The stage provides a concise alternative to a grouping operation when only the total count is needed. $countIf, $countMatch, and $matchCount are not standard MongoDB aggregation stage names.

Question 397

Which aggregation stage limits pipeline output to a fixed count?

1. $limit
2. $cap
3. $topLimit
4. $maximumDocs

Correct Answer: 1

Explanation:

The $limit aggregation stage restricts the number of documents passed to subsequent pipeline stages or returned when it is placed near the end of a pipeline. It is useful for pagination-related processing, sampling smaller result sets, or reducing downstream workload. When combined with $sort, it can be used to retrieve a defined number of highest- or lowest-ranked results. $cap, $topLimit, and $maximumDocs are not standard MongoDB aggregation stage names. Pipeline placement matters because $limit only affects documents that have reached that stage.

Question 398

Which aggregation stage skips a specified number of documents?

1. $offset
2. $advance
3. $skip
4. $discard

Correct Answer: 3

Explanation:

The $skip aggregation stage omits a specified number of documents before passing the remaining documents to the next pipeline stage. It is commonly used with $limit for basic offset-based pagination. When pagination uses $skip, sorting should generally be deterministic so that documents remain consistently ordered between requests. Large skip values can also require MongoDB to process many preceding documents, which may make other pagination approaches more efficient for large datasets. $offset, $advance, and $discard are not standard MongoDB aggregation stage names.

Question 399

Which aggregation stage sorts documents by specified fields?

1. $sort
2. $order
3. $arrange
4. $sortDocs

Correct Answer: 1

Explanation:

The $sort aggregation stage orders documents according to one or more specified fields. Each field can be sorted in ascending or descending order, and multiple fields can provide secondary ordering when values tie. $sort is frequently combined with $limit to efficiently express top-result requirements when appropriate indexes and pipeline placement are used. Sorting large datasets can consume significant memory and may require temporary disk usage depending on the workload and configuration. $order, $arrange, and $sortDocs are not standard MongoDB aggregation stage names.

Question 400

Which aggregation stage projects selected fields into a new document shape?

1. $fields
2. $project
3. $select
4. $reshape

Correct Answer: 2

Explanation:

The $project aggregation stage controls which fields appear in pipeline output and can also create computed fields using expressions. It is commonly used to reshape documents, exclude unnecessary data, rename or calculate output fields, and prepare results for later pipeline stages. $project can include or exclude fields according to MongoDB’s projection rules, with special handling for the _id field. $fields, $select, and $reshape are not standard MongoDB aggregation stage names. Proper projection can also reduce the amount of data passed through later stages.