Friday, March 13, 2009

What is a "dirty read"? (JDBC)

Question :What is a "dirty read"? (JDBC)
Answer :Quite often in database processing, we come across the situation wherein
one transaction can change a value, and a second transaction can read this
value before the original change has been committed or rolled back. This is
known as a dirty read scenario because there is always the possibility that
the first transaction may rollback the change, resulting in the second
transaction having read an invalid value. While you can easily command a
database to disallow dirty reads, this usually degrades the performance of
your application due to the increased locking overhead. Disallowing dirty
reads also leads to decreased system concurrency.

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