Exercise 15.8 Consider the following relational schema and SQL query:Suppliers(sid: intege...

Exercise 15.8 Consider the following relational schema and SQL query:

Suppliers(sid: integer, sname: char(20), city: char(20))
Supply(sid: integer, pid: integer)
Parts(pid: integer, pname: char(20), price: real)

SELECT S.sname, P.pnameFROM Suppliers S, Parts P, Supply YWHERE S.sid = Y.sid AND Y.pid = P.pid AND      S.city = ‘Madison’ AND P.price ≤ 1,000

1. What information about these relations does the query optimizer need to select a good query execution plan for the given query?
2. How many different join orders, assuming that cross-products are disallowed, does a System R style query optimizer consider when deciding how to process the given query? List each of these join orders.
3. What indexes might be of help in processing this query? Explain briefly.
4. How does adding DISTINCT to the SELECT clause affect the plans produced?
5. How does adding ORDER BY sname to the query affect the plans produced?
6. How does adding GROUP BY sname to the query affect the plans produced?