Deduplicate Ordered Event Stream | Dataford Interview Questions

In a Meta event ingestion pipeline, you receive a stream of event records in arrival order. Write a function that removes duplicate records while preserving the order of the first occurrence of each unique event.

A record is considered a duplicate if its event_id has already appeared earlier in the stream. Return the filtered list of records in the same relative order as their first appearance.

Formal Specification

Input: events, a list of event records
Each event record is a dictionary with at least the key "event_id"
Output: a list of event records containing only the first occurrence of each distinct event_id

Constraints

0 <= len(events) <= 10^5
Each event is a dictionary containing the key event_id
event_id values are hashable
Preserve the relative order of first occurrences

Function Signature

def deduplicate_events(events):

Your question is Deduplicate Ordered Event Stream. Start with the requirements in the Question tab.

Run and submit as often as you like. When you're ready, talk me through your approach or go straight to the code.

Problem