Problem Description

You are provided with event data detailing user interactions with design files.

Assume the following table schemas:

• files(file_id, creator_id)
  • creator_id is a VARCHAR user identifier.
• file_views(file_id, user_id, viewed_at)
  • user_id is an INTEGER user identifier.
  • Each row indicates that user_id viewed file_id at viewed_at.

A "share" is defined as an instance where a user other than the file's creator views that file.

Part 1: First Share Time Per Creator

Write a SQL query to determine, for each creator, the earliest time they ever shared one of their files. This is defined as the earliest viewed_at timestamp when a non-creator user viewed a file created by that creator.

Output Columns:

• creator_id
• first_shared_at

Notes:

• A creator viewing their own file should not be considered a "share".
• The creator_id (VARCHAR) and user_id (INTEGER) columns have different data types; ensure appropriate casting is handled.

Part 2: Closest Collaborator Model

For each individual file, identify the "first person it was shared with" as the earliest non-creator viewer of that specific file (based on its viewed_at timestamp).

Then, build a SQL query or model that, for each creator, identifies their closest collaborator. The closest collaborator is defined as the user who was the "first person shared with" for the creator's files the most number of times.

Output Columns:

• creator_id
• closest_collaborator_user_id
• collaborator_value (representing the count of files for which this collaborator was the first non-creator viewer)

Tie-breaking Rules: If multiple collaborators have the same collaborator_value for a given creator:

1. Choose the collaborator with the earliest overall first-share timestamp across the records where they were the "first person shared with" for that creator.
2. If still tied, choose the collaborator with the smallest user_id.