Systems and methods for avoiding database anomalies when maintaining constraints and indexes in presence of snapshot isolation

摘要

A system and method avoids anomalies in presence of data manipulation language (DML) plans maintaining dependent objects and snapshot isolation. An anomaly due to using a snapshot isolation level within the transaction is detected within a database transaction and the transaction is aborted based upon that detection. Involved in making the anomaly detection is determining whether a view of particular data accessed during the transaction under a snapshot isolation view to ensure read consistency differs from a view of the data under another isolation level, such as the read committed isolation level. Then a detection is made that an anomaly may occur if it is determined that the view of the data accessed during the transaction under the snapshot isolation differs from the view of the data under the other isolation level. Such anomaly avoidance prevents an indexed view being maintained nor a referential integrity constraint validated based on incorrect data.