REST API calls with Invoke-RestMethod in PowerShell - Time & Space Complexity

Time Complexity: REST API calls with Invoke-RestMethod

O(n)

Understanding Time Complexity

When using Invoke-RestMethod to call REST APIs, it's important to understand how the time taken grows as you make more calls.

We want to know how the total time changes when the number of API requests increases.

Scenario Under Consideration

Analyze the time complexity of the following code snippet.

$urls = @('https://api.example.com/data1', 'https://api.example.com/data2', 'https://api.example.com/data3')

foreach ($url in $urls) {
    $response = Invoke-RestMethod -Uri $url -Method Get
    Write-Output $response
}
    

This code sends a GET request to each URL in the list and outputs the response.

Identify Repeating Operations

• Primary operation: The foreach loop that sends an API request for each URL.
• How many times: Once for each URL in the list.

How Execution Grows With Input

Each additional URL means one more API call, so the total time grows as you add more URLs.

Input Size (n)	Approx. Operations
10	10 API calls
100	100 API calls
1000	1000 API calls

Pattern observation: The total work grows directly with the number of URLs.

Final Time Complexity

Time Complexity: O(n)

This means the time to complete all API calls grows linearly with the number of URLs.

Common Mistake

[X] Wrong: "All API calls happen instantly or at the same time, so adding more URLs doesn't increase time much."

[OK] Correct: Each API call waits for a response before moving on, so more calls add more total time.

Interview Connect

Understanding how repeated API calls affect time helps you write scripts that scale well and manage waiting times effectively.

Self-Check

"What if we changed the code to send all API requests at the same time using background jobs? How would the time complexity change?"