Questions

1. What's the difference between hot and cold testing?
2. What's the psql meta-command that shows the execution time?
3. What's the difference between the EXPLAIN and EXPLAIN ANALYZE commands?
4. Why don't we need to use DISTINCT with UNION ?
5. How can CTE be used to enhance performance? What's the limitation of CTEs?
6. What are the general partitioning strategies for big tables?
7. How we can tune statistics gathering for a certain column?
8. Let's assume we want to get the top three gurus based on the number of success stories, write a SQL query in two different ways.
9. What's the limitation of constraint exclusion?
10. What's the problem with cross-column correlation, and how can it be solved?