Write–read conflict

A read-write conflict (even english dirty read ) occurs in computer science, if two concurrent transactions, one transaction reads data that is written or changed by another transaction, but not yet confirmed ( committed) are.

Example

At the same time might be a feature that allows a user to display a list of connected users, perform the following transaction:

Without transaction isolation it can now come in the following manner to a read-write conflict which would lead to a not yet actually existing record is issued:

Remedy

Databases usually provide the possibility of transaction isolation. In isolation by serializing the above procedure might look as follows; the read-write conflict is avoided: