Oracle International Corporation

Archie Williams Brown

Joydip Kundu

Douglas Andrew Voss

Goutam Kulkarni

Richard L Frank

Raymond Guzman

Qinqin Wang

Parthasarathy Elangadu Raghunathan

Systems for high-performance, low-latency database log mining applications. A method commences upon receiving a log mining query. The query specifies desired results that correspond to a prior logical state of the database system. A first type of processing entity is invoked to process contents of the redo stream by loading metadata into a data dictionary, and a second type of processing entity is invoked to construct metadata from the redo stream, wherein the constructed metadata pertains only database objects referenced in the query. During the time that the first type of processing entity is processing contents of the redo stream by loading metadata into a data dictionary, a process of a second type serves incoming queries using a subset of entries in the redo stream. When the data dictionary is completed, a switchover point is reached and thenceforth, incoming queries are served using the first type of processing entity.

Low latency query processing over a series of redo records

A database rollback processor allows rollback, or rewind, of the data and metadata to a point at which a failover or other metadata change occurred, therefore 'rewinding' the metadata to a previous consistent point. The rollback processor identifies transaction entries in a redo log resulting in changes to the metadata. The changes are identified backward to a target recovery time. Transactions affecting the metadata are stored in a stack. The transactions are then backed out of the metadata according to the stack to restore the metadata to the state at the target recovery time. Data changes from the redo log may then be applied to the corresponding metadata as it existed at the target recovery time. Since the target recovery time is not bound by the timing of the snapshots, but rather may be at an arbitrary point chosen as the target recovery time, a failover, replication or recovery operation need not rely on the snapshot time.

Method and apparatus for data rollback

A method, system, and computer program product provides a data dictionary that can represent multiple versions of the schema objects, and which provides improved performance, reduced computing costs, and more accurate results in a variety of applications, such as in a database redo log mining system. A method of providing a data dictionary comprises the steps of determining whether information about the data object is present in a denormalized data dictionary history table, and if the information about the data object is not present in the denormalized data dictionary history table, then querying a normalized data dictionary to obtain the information about the data object, including a version identifier of the data object, and storing the version identifier and the obtained information about the data object including the version identifier in the denormalized data dictionary history table.

On-demand multi-version denormalized data dictionary to support log-based applications

A system, method, and computer program product communicate data dictionary information of database objects through a redo stream in the form of metadata, which provides the association between the internal numbers used by a database schema to identify database objects and the corresponding user-defined names of the database objects, in the redo stream itself, so that the association information may be easily and quickly used in the analysis of the redo stream of the database transactions. A method of communicating data dictionary information of database objects through a redo stream comprises the steps of performing a change to a first database data table, logging redo information representing the change to the first database data table to a redo stream, and logging information relating to internal identifier mapping information associated with the first database data table to the redo stream.

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Milford, NH, United States of America

Archie Williams Brown