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(b) I/O costs are of primary important to a DBMS because these costs typically dominate the time it takes to run most database operations

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Database  systems   Assignment  4  Solution    

1.    

(a)  A  DBMS  stores  data  on  external  storage  because  the  quantity  of  data  is  vast,  and   must  persist  across  program  executions.  

(b)  I/O  costs  are  of  primary  important  to  a  DBMS  because  these  costs  typically   dominate  the  time  it  takes  to  run  most  database  operations.  Optimizing  the  amount   of  I/O’s  for  an  operation  can  result  in  a  substantial  increase  in  speed  in  the  time  it   takes  to  run  that  operation.  

(c)  In  a  DBMS,  the  buffer  manager  reads  data  from  persistent  storage  into  memory   as  well  as  writes  data  from  memory  into  persistent  storage.  The  disk  space  manager   manages  the  available  physical  storage  space  of  data  for  the  DBMS.  

  2.    

(a)  No  one  file  organization  is  uniformly  superior  in  all  situations.  The  choice  of   appropriate  structures  for  a  given  data  set  can  have  a  significant  impact  upon   performance.  

(b)  Sorted  file  or  clustered  B+  tree   (c)  Hash  indexed  file  

(d)  Heap  file    

3,  4,  5  (Answer  omitted)    

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