Abstract: A method and mechanism for identifying one or more transactions that have modified or created an object in a database system. Also disclosed is a method and mechanism to compensate for the effects of a transaction in a database system is disclosed. The disclosed approach can be applied to perform auditing for changes and/or transactions in a database system and for identifying the scope of changes and data accesses made by a transaction in the system.

Abstract: Disclosed is a mechanism, system, interface, and process to allow specification of a new table decoration clause to obtain one or more past version of one or more data items. The version query provides for a direct interface to get multiple versions of the row(s). In addition, information about the past versions can be retrieved and displayed along with the past versions. Also disclosed are algorithms, mechanisms, and processes that are employed to implement a query upon past versions. In one approach, the version query can be defined as either “rowid”-based access or non-rowid based access. With rowid based access, a given rowid is used to identify the data for which past versions are desired. Also disclosed is a process for determining one or more life intervals when given a key.

Abstract: A method and mechanism for identifying one or more transactions that have modified or created an object in a database system. Also disclosed is a method and mechanism to compensate for the effects of a transaction in a database system is disclosed. The disclosed approach can be applied to perform auditing for changes and/or transactions in a database system and for identifying the scope of changes and data accesses made by a transaction in the system.

Abstract: A method and mechanism to compensate for the effects of a transaction in a database system is disclosed. Also disclosed is a method and mechanism for identifying one or more transactions that have modified or created an object in a database system. The disclosed approach can be applied to perform auditing for queries in a database system and for identifying the scope of changes and data accesses made by a transaction in the system.

Abstract: The present invention provides a uniqueness-required index and a corresponding non-uniqueness count to support deferred uniqueness constraint enforcement. A uniqueness-required index stores duplicate occurrences of indexed data values that occur during statement or transaction processing. The non-uniqueness count associated with the uniqueness-required index provides a count of the number of indexed data values that occur more than once in the index. Where a non-uniqueness count is not equal to zero, a uniqueness constraint violation remains unresolved. Where an unresolved constraint violation exists at enforcement time, the effects of the processing are removed. A currently non-unique count can be used to represent the number of uniqueness-required indexes that are "currently non-unique". The currently non-unique count can be examined to determine whether there are any unresolved uniqueness constraint violations.

Abstract: The present invention provides a uniqueness-required index and a corresponding non-uniqueness count to support deferred uniqueness constraint enforcement. A uniqueness-required index stores duplicate occurrences of indexed data values that occur during statement or transaction processing. The non-uniqueness count associated with the uniqueness-required index provides a count of the number of indexed data values that occur more than once in the index. Where a non-uniqueness count is not equal to zero, a uniqueness constraint violation remains unresolved. Where an unresolved constraint violation exists at enforcement time, the effects of the processing are removed. A currently non-unique count can be used to represent the number of uniqueness-required indexes that are "currently non-unique". The currently non-unique count can be examined to determine whether there are any unresolved uniqueness constraint violations.

Abstract: A method and system for providing isolation levels in a database system is provided. A serializable isolation level is provided by causing all statements in a transaction to see a "snapshot" of the database. A snapshot includes only those changes made to the database by a particular set of transactions. For example, the snapshot for a given transaction may include only the changes made by transactions that committed prior to the execution of the given transaction. The set of all transactions whose changes are included in a particular snapshot of the database is referred to as the snapshot set. Concurrently executing transactions may update the database while a serializable transaction is being executed. Updates that are not included in the snapshot of the serializable transaction are undone prior to processing each statement in the serializable transaction to recreate the data as it existed in the snapshot.