The MongoDB Aggregation Framework Chapter 3 - Core Aggregation - Combining Information
In this article i am gone to share MongoDB-University
Course: The MongoDB Aggregation Framework Chapter 3 - Core
Aggregation - Combining Information Quiz Answer with
you..
The $lookup Stage
Which of the following statements is true about the $lookup stage?
- The collection specified in from cannot be sharded
- You can specify a collection in another database to from
- $lookup matches between localField and foreignField with an equality match
- Specifying an existing field name to as will overwrite the the existing field
$graphLookup Introduction
Which of the following statements apply to $graphLookup operator? check
all that apply
- Provides MongoDB with graph or graph-like capabilities
- $graphLookup provides MongoDB a transitive closure implementation
- $graphLookup depends on $lookup operator. Cannot be used without $lookup
- $lookup and $graphLookup stages require the exact same fields in their specification.
- $graphLookup is a new stage of the aggregation pipeline introduced in MongoDB 3.2
$graphLookup: Simple Lookup
Which of the following statements is/are correct? Check all that
apply.
- connectToField will be used on recursive find operations
- as determines a collection where $graphLookup will store the stage results
- startWith indicates the index that should be use to execute the recursive match
- connectFromField value will be use to match connectToField in a recursive match
$graphLookup: maxDepth and depthField
Which of the following statements are incorrect? Check all that
apply
- maxDepth only takes $long values
- maxDepth allows to specify the number of recursive lookups
- depthField determines a field, in the result document, which specifies the number of recursive lookup needed to reach that document
- depthField determines a field, which contains the value number of documents matched by the recursive lookup
$graphLookup: General Considerations
Consider the following statement:
``$graphLookup`` is required to be the last element on the
pipeline.
Which of the following is true about the statement?
- This is correct because of the recursive nature of $graphLookup we want to save resources for last.
- This is incorrect. graphLookup needs to be the first element of the pipeline, regardless of other stages needed to perform the desired query.
- This is incorrect. $graphLookup can be used in any position of the pipeline and acts in the same way as a regular $lookup.
- This is correct because $graphLookup pipes out the results of recursive search into a collection, similar to $out stage.
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