Optimistic-CC-Performance

Optimistic-CC-Performance - Evaluation Criterion 1 Degree...

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Optimistic CC Performance Evaluation Criterion 1. Degree of Concurrency Less reshuffle High degree of concurrency 2. Resources used to recognize - Lock tables - Time stamps - Read/write sets - Complexity 3. Costs - Programming ease Scheduler Recognizes or Reshuffles history history
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Optimistic CC Performance General Comments Information needed by Concurrency Controllers Locks on database objects (System-R, Ingres, Rosenkrantz…) Time stamps on database objects (Thomsa, Reed) Time stamps on transactions (Kung, SDD-1, Schlageter, Bhargava…) Observations Time stamps mechanisms more fundamental than locking Time stamps carry more information Checking locks costs less than checking time stamps
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General Comments (cont.) When to synchronize First access to an object (Locking, pessimistic validation) At each access (question of granularity) After all accesses and before commitment (optimistic validation) Fundamental notions
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This note was uploaded on 12/23/2009 for the course DBST 663 taught by Professor Tba during the Spring '09 term at MD University College.

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Optimistic-CC-Performance - Evaluation Criterion 1 Degree...

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