Identify Session with Maximum Overlapping Sessions Count
Company: PayPal
Role: Data Scientist
Category: Data Manipulation (SQL/Python)
Difficulty: medium
Interview Round: Onsite
sessions
| session_id | start_time | end_time |
| 1 | 2023-01-01 09:00:00 | 2023-01-01 10:00:00 |
| 2 | 2023-01-01 09:30:00 | 2023-01-01 11:00:00 |
| 3 | 2023-01-01 10:30:00 | 2023-01-01 12:00:00 |
| 4 | 2023-01-01 13:00:00 | 2023-01-01 14:00:00 |
##### Scenario
SQL screen – session overlap analysis
##### Question
Given the sessions table, write SQL to return the session_id that overlaps with the greatest number of other sessions and the overlap count.
##### Hints
Self-join on intervals where start_a < end_b AND end_a > start_b; aggregate and order by count desc.
Quick Answer: This question evaluates temporal interval reasoning, set-based querying and aggregation skills, focusing on identifying and counting overlapping time intervals using SQL or equivalent Python data-manipulation tools.