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<h1>Pessimistic Locking</h1>
<p>In pessimistic locking
approach an entity is locked for the entire time the entity is in application
memory (often in the form of an object). A read lock indicates that the object
can be read but not modified or deleted by the other transactions. A write lock
indicates that the object is locked exclusively and only the current
transaction can read, modify or delete the object. </p>
<p><b>Advantage</b>: pessimistic
locking is easy to implement and guarantees that your changes to the database
are made consistently and safely. </p>
<p><b>Disadvantage</b>: pessimistic
locking is not scalable; in systems with many users or long-running
transactions, the waiting time for a lock to be released can be too long.</p></div>
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This revision (1) was last Modified 2007-05-22T11:46:16 by Tetyana.
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