Supported data types in Firebase - Time & Space Complexity

Time Complexity: Supported data types

O(1)

Understanding Time Complexity

When working with Firebase, it is important to understand how the types of data you store affect the speed of your operations.

We want to know how the time to save or read data changes as the amount and type of data grows.

Scenario Under Consideration

Analyze the time complexity of saving different data types to Firebase Firestore.

const docRef = firestore.collection('users').doc('user1');

await docRef.set({
  name: 'Alice',
  age: 30,
  isActive: true,
  scores: [10, 20, 30],
  address: { city: 'NY', zip: '10001' }
});

This code saves a document with various supported data types like string, number, boolean, array, and object.

Identify Repeating Operations

Look at what happens when saving data:

• Primary operation: One write API call to save the document.
• How many times: Once per document save, regardless of data types inside.

How Execution Grows With Input

Saving a document involves one write call no matter how many fields or data types it contains.

Input Size (n)	Approx. API Calls/Operations
1 field	1 write call
10 fields	1 write call
100 fields	1 write call

Pattern observation: The number of API calls stays the same even if the data size grows.

Final Time Complexity

Time Complexity: O(1)

This means saving data of any supported type takes a constant number of API calls, no matter the data size.

Common Mistake

[X] Wrong: "Saving more fields or complex data types means more API calls and slower performance."

[OK] Correct: Firebase groups all fields in one document write, so the number of API calls stays the same regardless of data complexity.

Interview Connect

Understanding how Firebase handles data types and API calls shows you know how cloud databases work efficiently behind the scenes.

Self-Check

"What if we split the data into multiple documents instead of one? How would the time complexity change?"

Practice

1. Which of the following is NOT a supported data type in Firebase Firestore?

easy

A. String

B. Function

C. Boolean

D. GeoPoint

Solution

1. Step 1: Review Firebase supported data types

   Firebase supports strings, booleans, numbers, arrays, maps, timestamps, and geopoints.

2. Step 2: Identify unsupported type

   Functions are not stored as data types in Firestore; they are part of code logic, not data.

3. Final Answer:

   Function -> Option B

4. Quick Check:

   Functions are not data types in Firestore [OK]

Hint: Remember: Firestore stores data, not code like functions [OK]

Common Mistakes:

• Confusing code functions with data types
• Thinking all JavaScript types are supported
• Assuming Firestore stores executable code

2. Which is the correct way to store a timestamp in Firebase Firestore?

easy

A. Store as a number representing milliseconds since epoch

B. Use a string with date format like '2024-06-01'

C. Use the Firebase Timestamp type

D. Use a boolean true or false

Solution

1. Step 1: Understand Firestore timestamp storage

   Firestore has a special Timestamp type to store date and time accurately.

2. Step 2: Compare options

   Strings and numbers can store dates but lack Firestore's timestamp features; booleans are unrelated.

3. Final Answer:

   Use the Firebase Timestamp type -> Option C

4. Quick Check:

   Timestamp type stores dates best [OK]

Hint: Use Firebase Timestamp for dates, not strings or numbers [OK]

Common Mistakes:

• Storing dates as plain strings
• Using numbers without Timestamp type
• Confusing booleans with dates

3. What will be the data type of the field location after this Firestore document is saved?

const docData = { location: new firebase.firestore.GeoPoint(40.7128, -74.0060) };

medium

A. GeoPoint

B. Array

C. String

D. Map

Solution

1. Step 1: Identify the data type used

   The code uses new firebase.firestore.GeoPoint() which creates a GeoPoint object.

2. Step 2: Understand Firestore storage

   Firestore stores GeoPoint objects as GeoPoint type, representing geographic coordinates.

3. Final Answer:

   GeoPoint -> Option A

4. Quick Check:

   GeoPoint stores latitude and longitude [OK]

Hint: GeoPoint objects store coordinates, not strings or arrays [OK]

Common Mistakes:

• Thinking GeoPoint is stored as string
• Assuming coordinates are arrays
• Confusing GeoPoint with map type

4. You try to save this data in Firestore:

{ name: 'Alice', age: '25' }

But you want age to be a number. What is the error and how to fix it?

medium

A. No error, Firestore converts string to number automatically

B. No error, but age should be stored as boolean true

C. Error: Firestore does not allow strings, use boolean instead

D. Error: age is string, fix by storing age as number 25

Solution

1. Step 1: Check data types in the object

   Age is stored as a string '25', not a number 25.

2. Step 2: Understand Firestore type strictness

   Firestore stores data as given; it does not convert string to number automatically.

3. Final Answer:

   Error: age is string, fix by storing age as number 25 -> Option D

4. Quick Check:

   Store numbers as numbers, not strings [OK]

Hint: Store numbers as numbers, not strings to avoid type errors [OK]

Common Mistakes:

• Assuming Firestore auto-converts types
• Using booleans for numbers
• Ignoring type mismatch warnings

5. You want to store a user's profile with name, age, location (latitude and longitude), and signup date in Firestore. Which data types should you use for location and signupDate fields?

hard

A. location as GeoPoint, signupDate as Timestamp

B. location as Map with lat/lng numbers, signupDate as string

C. location as Array of numbers, signupDate as number (milliseconds)

D. location as string 'lat,lng', signupDate as boolean true

Solution

1. Step 1: Identify best types for location and date

   Firestore provides GeoPoint for geographic coordinates and Timestamp for dates.

2. Step 2: Evaluate options

   Using GeoPoint and Timestamp ensures correct storage, querying, and indexing.

3. Final Answer:

   location as GeoPoint, signupDate as Timestamp -> Option A

4. Quick Check:

   Use GeoPoint and Timestamp for location and dates [OK]

Hint: Use GeoPoint for locations and Timestamp for dates [OK]

Common Mistakes:

• Storing dates as strings
• Using arrays for location
• Confusing booleans with dates