Abstract  A distributed database system consists of a number  of sites over a network and has a huge amount of da ta. Besides a  high  number  of  users  use  these  data.  The  lock  manag er  coordinates  the  use  of  database  resources  among distributed  transactions.  Because  a  distributed  transaction  con sists  of  several  participants  to  execute  over  sites;  all  participants  must  guarantee  that  any  change  to  data  will  be  permanent   in  order  to  commit  the  transaction.  Because  the  number  of  users  is  increasingly  growing  and  the data  must  be  available   all  of  the  time,  this  research  applied  a  new  method  for  reducing  the  size  of  lockable  entities  to  allow  several  transactions  to  access  the  same  database  row  simultaneously,  the   other  attributes remain  available to other users if needed. It is possible  to do that by increasing the granularity hierarchy  tree one more level down at  the attributes. The experimental results proved tha t using attribute level locking will increase the throughput and enhance the  system performance.   

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[15] Wu H., Chin W., and Jaffar J., An Efficient Distributed Deadlock Avoidance Algorithm for the AND Model, IEEE Transactions on Software Engineering , vol. 28, no. 1, pp. 18-29, 2002. Khaled Maabreh is a lecturer in computer information system at Zarqa University, Jordan. He holds PhD degree in computer science from Amman Arab University for Graduate Studies in 2008. He has more than 17 years of experience including developing IT-related projects. He also teaches different courses at BSc level in computer science and computer information systems. Alaa Al-Hamami is senior lecturer in computer science. He holds a BS in physics from Baghdad University, in 1970, MSc in computer science from Loughborough University, England in 1979, and a PhD degree in computer science-database security from the University of East Anglia-England in 1984. He has a membership in many different scientific societies including ACM and IEEE. He is a deanship of Graduate College of Computer Studies- Amman Arab University for Graduate Studies. He has more than 31 years of experience including extensiv e project management experience in planning and leading a range of IT-related projects in addition to management posts. He has more than 117 published papers in different indexed journals. He supervises more than 50 PhD and MSc students in computer science, information management and integration, security, and knowledge management. He also leads and teaches modules at BSc, MSc and PhD levels in computer science and security.