distributed database systems question

Discussion in 'Databases' started by bufos, Jun 29, 2007.

  1. #1
    Hi,
    Iwould like somebody to help me with this exercise :

    Consider the following relations:

    BOOKS (Book#, Primary_author, Topic, Total_stock, $price)
    BOOKSTORE (Store#, City, State, Zip, Inventory_value)
    STOCK (Store#, Book#, Qty)

    Consider a distributed database for a bookstore chain called National Books with 3 sites called EAST, MIDDLE, and WEST. Consider that BOOKS are fragmented by $price amounts into:

    B1:BOOK1:up to $20.
    B2:BOOK2:from 20.01 to $50.
    B3:BOOK3:from 50.01 to $100.
    B4:BOOK4100.01 and above.

    Similarly, BOOKSTORES are divided by Zipcodes into:

    S1:EAST:Zipcodes up to 35000.
    S2:MIDDLE:Zipcodes 35001 to 70000.
    S3:WEST:Zipcodes 70001 to 99999.

    Assume that STOCK is a derived fragment based on BOOKSTORE only.

    a. Consider the query:
    SELECT Book#, Total_stock
    FROM Books
    WHERE $price > 15 and $price < 55;

    Assume that fragments of BOOKSTORE are non-replicated and assigned based on region. Assume further that BOOKS are allocated as:

    EAST:B1,B4.
    MIDDLE:B1,B2.
    WEST:B1,B2,B3,B4.

    Assuming the query was submitted in EAST, what remote subqueries does it generate? (write in SQL).

    b. If the bookprice of Book#= 1234 is updated from $45 to $55 at site MIDDLE, what updates does that generate? Write in English and then in SQL.

    c. Given an example query issued at WEST that will generate a subquery for MIDDLE.

    d. Write a query involving selection and projection on the above relations and show two possible query trees that denote different ways of execution.



    The only I have done is to seperate the two tables
    
    BOOK1=select *
    from BOOKS
    where $price<=20;
    
    BOOK2=select *
    from BOOKS
    where ($price >=20.01)AND($price<=50);
    
    BOOK3=...
    BOOK4=...
    
    EAST=select *
    from BOOKSTORE
    where Zip<=35000;
    
    MIDDLE=...
    WEST=....
    
    Code (markup):
    Then I don't know what I have to do.
    I am interested only for question a then I will find it alone.

    Thanks a lot!
     
    bufos, Jun 29, 2007 IP
  2. yugolancer

    yugolancer Well-Known Member

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    #2
    Which question if you don't mind?
    I wasn't able to see any question here.
     
    yugolancer, Jul 2, 2007 IP