Time-series collections in MongoDB - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a time-series collection named 'sensorData'.

MongoDB

db.createCollection('sensorData', { [1]: { timeField: 'timestamp', metaField: 'deviceId', granularity: 'seconds' } })

Drag options to blanks, or click blank then click option'

Atimeseries

BtimeSeries

Ctime_series

Dtime-series

Attempts:

3 left

💡 Hint

Common Mistakes

Using camelCase like 'timeSeries' instead of 'timeseries'.

Adding underscores or hyphens in the option name.

The correct option is timeseries. This is the exact option name MongoDB expects to create a time-series collection.

2fill in blank

medium

Complete the code to insert a document with a timestamp and metadata into the 'sensorData' collection.

MongoDB

db.sensorData.insertOne({ timestamp: new Date(), [1]: 'device123', temperature: 22.5 })

Drag options to blanks, or click blank then click option'

Ameta

BmetaField

Cmetadata

DdeviceId

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'meta' or 'metadata' instead of the exact metaField name.

Using 'metaField' as a field name in the document.

The metadata field is named deviceId as defined in the collection options. This field stores device identification info.

3fill in blank

hard

Fix the error in the query to find documents where temperature is greater than 20.

MongoDB

db.sensorData.find({ temperature: { [1]: 20 } })

Drag options to blanks, or click blank then click option'

A$lt

B$gte

C$gt

D$lte

Attempts:

3 left

💡 Hint

Common Mistakes

Using $lt or $lte which mean less than.

Using $gte which means greater than or equal, not strictly greater.

The operator $gt means 'greater than'. It correctly filters documents with temperature above 20.

4fill in blank

hard

Fill both blanks to create an aggregation pipeline that groups data by deviceId and calculates average temperature.

MongoDB

db.sensorData.aggregate([ { $group: { _id: '[1]', avgTemp: { $avg: '[2]' } } } ])

Drag options to blanks, or click blank then click option'

AdeviceId

Btemperature

Ctimestamp

Dmeta

Attempts:

3 left

💡 Hint

Common Mistakes

Grouping by timestamp instead of deviceId.

Averaging the wrong field like timestamp or meta.

The _id field groups by deviceId. The average is calculated on the temperature field.

5fill in blank

hard

Fill all three blanks to create a time-series collection with a custom granularity and insert a sample document.

MongoDB

db.createCollection('weatherData', { [1]: { timeField: '[2]', metaField: '[3]', granularity: 'minutes' } })

Drag options to blanks, or click blank then click option'

Atimeseries

BrecordedAt

Clocation

DtimeSeries

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'timeSeries' instead of 'timeseries' for the option name.

Mixing up the timeField and metaField names.

The collection option is timeseries. The time field is recordedAt and the metadata field is location.