Find Users with Seven Consecutive Impression Days

A user qualifies as a super user if they have at least one impression on each day of any run of seven consecutive calendar days. Find every qualifying user using PostgreSQL. ### Input Table `impressions` | Column | Type | Meaning | | --- | --- | --- | | `impression_id` | INTEGER | Unique impression identifier; primary key | | `user_id` | INTEGER | Non-null user identifier | | `impression_date` | DATE | Non-null calendar date of the impression | ### Output Contract Write one read-only PostgreSQL query returning a single column, `user_id`, with each qualifying user exactly once, ordered by `user_id` ascending. ### Example Suppose user `10` has impressions on January 1, 2, 3, 4, 5, 6, and 7 of the same year, with two impressions on January 3. User `20` has impressions on January 1, 2, 3, 5, 6, 7, and 8. Expected result: | user_id | | --- | | 10 | User `20` has seven distinct impression dates, but no seven-day consecutive run because January 4 is missing. ### Constraints and Clarifications - The exercise uses the supplied calendar dates directly; no timestamp-to-time-zone conversion is needed. - Several impressions on the same day count as one active day for that user. - A run may cross a month or year boundary. - A run longer than seven days qualifies, and multiple qualifying runs still produce one user row. - Search the entire table history; this is not a requirement to be active on the seven days immediately preceding today. ```hint Compare consecutive active dates Deduplicate each user's active dates before measuring runs. A streak is a property of consecutive dates, not simply the number of impression rows. ```