- Reading changes in t2 from t1 before its committed
- Changes by t1 are lost due to updates from t2
Non repeatable reads
- Repeated reads of the same record in one transaction results in different values. Happens at "
dirty read A transaction reads data written by a concurrent uncommitted transaction.
nonrepeatable read A transaction re-reads data it has previously read and finds that data has been modified by another transaction (that committed since the initial read).
phantom read A transaction re-executes a query returning a set of rows that satisfy a search condition and finds that the set of rows satisfying the condition has changed due to another recently-committed transaction.
serialization anomaly The result of successfully committing a group of transactions is inconsistent with all possible orderings of running those transactions one at a time.