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surfinhu

Hi i am new,I have a problem in understanding the query decomposition in D-DB. Can anyone help me to understand the first question of the exercise 25.21 of Elmasri-Navath 4th edition?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_stockFROM BooksWHERE $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).


yordan

Is this a conceptual understanding problem ? Or is it an exercise a teacher asked you to perform ? In the second case, not sure the answer will arrive before the deadline...