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<p>A <a href="page.php?w=database_transaction">transaction</a> is usually the result of an execution of a program that accesses or changes the contents of a database. A transaction is different from a stream because a stream only allows read-only operations, and transactions can do both read and write operations. This means in a stream, multiple users can read from the same piece of data, but they cannot both modify it. A database must let only one transaction operate at a time to preserve <a href="page.php?w=data_consistency">data consistency</a>.</p><p>
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