International Business Machines Corporation

Robert D Goldring

Inderpal Singh Narang

Joshua Wai-Ho Hui

Scott K Chan

A system and method for replicating files in a source file system that is linked to a source DBMS which stores metadata pertaining to files in the source file system. The files and metadata are replicated to a target system having a target file system linked to a target DBMS. File references are also mapped from the source to the target. Also, only the most recent consistent version of files that have changed at the source and that have had insert or update references in the source DBMS are copied over to the target file system, thereby minimizing unnecessary replications.

System and method for replicating external files and database metadata pertaining thereto

A method, apparatus and program storage device for optimizing a query in a relational database management system is provided. The query including aggregate and grouping functions. An application table is preferably located in a source site and an aggregation operation is performed from a target site. After an initial aggregation operation performed from the source-based application table, the further aggregation operations are incrementally performed, by aggregating only the newly inputted relational database data into the target-based base aggregates table. This procedure allows the transformed query to perform more efficiently than the original query, while providing same results.

Data replication in data warehousing scenarios

A method of performing design synchronization in a computer system is described. At least a portion of a source schema and at least a portion of a target schema are compared. The target schema is modified based on the differences therebetween. In a preferred fashion, design changes are made at the target with target-specific syntax and the minimum number of equivalent operations.

Method of and apparatus for performing design synchronization in a computer system

A computing system associates time series data with data base changes, received from concurrent processes, that are recorded in an activity log by defining a data base table to include a column in which a system clock time stamp value can be recorded when initializing a new copy of the data. Initialization can be set to occur automatically at periodic intervals or whenever a fresh copy of a set of data records is requested by a system process. The writing of the time stamp data associates a time value with the copy initialization activity and makes time series data available to processes that otherwise would have no time knowledge. The prior user-defined data base does not have to be modified to utilize the time stamp feature because a new, system-defined table is used.

Consistent recreation of events from activity logs

A computer processing system that receives sequences of changes to a data base and records them into an activity log for later retrieval also maintains a consistent change data table that contains sufficient change information for each of the changes to the data base such that the changes can be propagated through multiple copies of the data base by consulting the consistent change data table. The consistent change data includes information sufficient to permit reconstruction of the data base to reflect the condition of the data base at any moment of time in the activity log. Because the consistent change data is complete, it permits producing multi-generational copies of data base tables for replication from one copy level to any other subsequent level, or iteration, of copy.

Lossless distribution of time series data in a relational data base

A relational data base management system permits users to specify copy operations without being burdened with specifying details of structure, copy refresh algorithm, and the like. The attributes a user must specify when requesting snapshot copies is reduced by defining data structures with attributes such that specifying the name of a table, whether a user data table or snapshot, specifies the copying scheme that will be used. Any ambiguity is resolved by interactively querying the user. When a user initially defines, or registers, a source table, the user specifies a set of predefined attributes, including table structure and completeness. When a user later requests a snapshot copy, the system automatically determines the nature of the copy operation to be performed by matching the table name with its registered attributes. This permits the system to automatically determine details such as the structure of the target table, the manner in which snapshot refresh will occur, and whether the target table can be created from a snapshot copy or if the original user table must be consulted. In this way, specifying copies in a relational data base system is simplified.

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Morgan Hill, CA, United States of America

Robert D Goldring