The visits table holds one row for each page that a user opened: 100 000 rows. The support page looks up all the visits of one user, and it is slow.

The query is: SELECT * FROM visits WHERE user_id = 4242

1. Show the plan of that query. Do not run the query itself.
2. Which kind of scan does the plan use?
3. What is the total cost of the plan? Give the number after the two dots.
4. Run the query with EXPLAIN ANALYZE. How many rows did the scan read and throw away?