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Exercises for Distributed Data Management

Institut für Informationssysteme – TU Braunschweig - http://www.ifis.cs.tu-bs.de

Technische Universität Braunschweig Institut für Informationssysteme http://www.ifis.cs.tu-bs.de Christoph Lofi José Pinto

Distributed Data Management

  Please  make  sure  you  can  answer  the  following  correctly:  

1. Which  sharing  architectures  are  usually  used  in  DDBMS?  What  does  distinguish   them?    

2. Define  partitioning,  fragmentation,  and  allocation.    

3. When  partitioning,  what  does  it  mean  if  the  Completeness  Rule  is  violated?    

4. Which  operation  is  used  when  performing  Horizontal  fragmentation?  

5. How  might  a  distributed  database  designed  for  a  local  area  network  (LAN  )  differ   from  one  designed  for  a  wide  area  network  (WAN)?    

6. When  deciding  for  a  good  fragmentation  and  allocation,  which  criteria  should  be  op-­‐

timized?    

7. What  are  the  advantages  of  Horizontal  Fragmentation?  

8.  Is  it  a  good  idea  to  use  full  replication?  If  yes,  in  which  cases?    

9. Consider  the  following  relation  that  is  fragmented  horizontally  by  city   employee  (name,  address,  salary,  city)  

  Assume  that  each  fragment  has  two  replicas:  one  is  in  Berlin  and  the  other  one  is   stored  locally  at  the  corresponding  city.    Describe  a  processing  strategy  for  the  following   queries  entered  at  Braunschweig:  

a) Find  all  the  employees  names  at  Braunschweig.  

b) Find  the  average  salary  of  all  employees.  

c) Find  the  lowest  paid  employee  at  each  of  the  following  cities:  Stuttgart,  Manheim,   and  Frankfurt.  

d) Find  the  highest  paid  employee  at  the  company.  

     

 

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