database - What is dirty read? And How does it hinder the performance issues? -

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i have heard term dirty read many times in beginning career of development. somehow understand want expert's light on it.

does diminish performance issues ? or making wrong assumptions. please provide characteristic also.

thanks in advance.

quite in database processing, come across situation wherein 1 transaction can change value, , second transaction can read value before original change has been committed or rolled back. known dirty read scenario because there possibility first transaction may rollback change, resulting in second transaction having read invalid value.

while can command database disallow dirty reads, degrades performance of application due increased locking overhead. disallowing dirty reads leads decreased system concurrency.


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