Abstract: A method and system for use in a computing environment for selecting a subset of records from a set of records for placement of the subset of records in a plurality of destinations. A group of replica records is formed for a record of the subset of records, and a destination identification is assigned to each replica record, except one, of the group of replica records. A replica record associated with one of the plurality of destinations can be selected and can be placed in the associated destination.

Abstract: A method, apparatus, and article of manufacture for optimizing database queries. The query is analyzed to determine whether at least a portion of the query can be evaluated using a plurality of parallel operations without data redistribution. If so, then the most efficient query execution plan that uses these parallel operations is constructed and executed.

Abstract: A method, apparatus, and article of manufacture for maintaining a materialized view derived from at least one base table in a database stored on a computer. An update is performed to the base table in a transaction. Thereafter, the materialized view is accessed to identify affected records therein using at least one mechanism, such as an isolation level or update- and exclusive-locks, to guarantee consistency while avoiding deadlocks with other transactions that modify at least one base table of the materialized view and to improve concurrency with other transactions that are accessing the materialized view when the modification to the base table is applied to the materialized view.

Abstract: A method, apparatus, and article of manufacture for the incremental maintenance of summary tables with complex grouping expressions.

Abstract: A method, apparatus, and article of manufacture for optimizing database queries using an automatic summary table. A query is analyzed using matching and compensation tests between the query at least one correlated subquery within the query and the automatic summary table to determine whether expressions occurring in the query, but not in the automatic summary table, can be derived using the automatic summary table. If so, the query is rewritten so that the automatic summary table is used.

Abstract: The invention herein provides method and apparatus, including software for determining a set of materialized views or indices of the contents or a subset of the contents of a database in a data processing system to be created for one or more users of the database. The method and apparatus provide method and means for evaluating a workload presented by a user to the database; evaluating the data processing system characteristics; evaluating the database characteristics; and, using the above evaluations for recommending a set of suitable materialized views or indices to the user.

Abstract: A method, apparatus, and article of manufacture for optimizing database queries using subsumption tests between the query and at least one summary table that comprises a cube index to determine whether an expression in the query can be subsumed in the summary table. The summary table stores at least one materialized view involving at least one GROUP BY operation that computes at least one of the following: (1) a cube, (2) a rollup, (3) a grouping set, and (4) a concatenation of cubes, rollups, grouping sets, and one or more grouping items. When the expression in the query can be subsumed in the summary table, the query is rewritten to use the summary table.

Abstract: A system, method, and article of manufacture for supporting summary tables in a database system that does not otherwise support summary tables is disclosed. The system generally comprises a central program and one or more database systems that may be heterogeneous. At least one of the database systems does not support the generation, maintenance, and/or querying of summary tables. The central program is configured to communicate with the database systems and to identify relations corresponding to summary tables (also referred to as materialized views) within one or more of the database systems. The central program may initiate the generation of summary tables, which may be populated local to the central program or local to one or more of the database systems. The central program may also maintain or coordinate maintenance of the summary tables.

Abstract: A system, method, and article of manufacture for supporting summary tables in a distributed database environment is disclosed. The system generally comprises a central program and a plurality of remote database systems that may be heterogeneous. The central program is configured to communicate with the database systems and to support summary tables (also referred to as materialized views) within the central program or within one or more of the database systems. The summary tables may contain summary data from one or more of the database systems. The central program may initiate the generation of summary tables, which may be populated local to the central program or local to one or more of the database systems. The central program may also maintain or coordinate maintenance of the summary tables.

Abstract: An optimization technique that reorders outerjoins and antijoins with inner joins in a bottom-up optimizer of a relational database management system (RDBMS).

Abstract: A method, apparatus, and article of manufacture for optimizing database queries uses a derived summary table, wherein a definition of the summary table is based on a full select statement that is materialized in the table and describes how the summary table was derived. The summary table definition can be a complex query involving nested GROUP BY operations as well as complex HAVING clauses with subqueries or join operations. A query is analyzed using subsumption tests between the query and the definition of the summary table to determine whether expressions occurring anywhere in the query, but not in the summary table, can be subsumed in the summary table. In performing the query, an expression in the query is subsumed in the summary table when the expression can be re-derived from one or more of the columns of the summary table.

Abstract: A method, apparatus, and article of manufacture for optimizing database queries using subsumption tests between the query and at least one summary table that comprises a cube index to determine whether an expression in the query can be subsumed in the summary table. The summary table stores at least one materialized view involving at least one GROUP BY operation the computes at least one of the following: (1) a cube, (2) a rollup, (3) a grouping set, and (4) a concatenation of cubes, rollups, grouping sets, and one or more grouping items. When the expression in the query can be subsumed in the summary table, the query is rewritten to use the summary table.

Abstract: The invention provides method and apparatus for use in a database management system for managing a database containing data, where the database has storage for storing data in the database, and has an instruction processor for processing instructions for managing data stored in the database. The database has a constraint manager for managing constraints on said data stored in the database. The invention provides efficient method and means for deferred checking of data after bulk loading into said database for violation of constraints by determining an appropriate procedure for constraint checking by determining whether constraint checking is required; and if it is required, determining whether to implement full, or incremental checking for compliance with said constraints; and then checking the data in the database in accordance with the determined constraint checking procedure.

Abstract: A method for typed view hierarchies for an object-relational database management (OPDBMS). The views in the hierarchy are merged into a unified hierarchy view through case expressions for mapping and wrapping of overloaded columns. During the merge, the underlying logical tables are eliminated which results in a simplified query graph. The transformation is a non-loss operation which condenses the type information within the case expressions. This allows update, delete and insert operations to be resolved on the query graph on a local level. Using query rewrite rules, the case expressions may be simplified further.

Abstract: An optimization technique for SQL queries. A query is analyzed to determine whether it includes one or more scalar subqueries and one or more existential subqueries. The scalar subqueries and the existential subqueries are transformed into join operations using subsumption, and the join operations are merged into a single join query block. The join query block can then be executed in the computer to efficiently retrieve data from the relational database.

Abstract: A method, apparatus, and article of manufacture for optimizing database queries using a materialized view for a table referenced in the query, wherein the materialized view has different properties than the referenced table. The materialized view may be replicated across multiple processors of the computer system, so that some or all of the query can be executed in a local fashion wherein there is no data movement required to perform the operations. The materialized view also may be partitioned across multiple processors of the computer system using a different partitioning key than the referenced table. The materialized view may be a vertical and/or horizontal subset of the table, so that only selected columns and/or tuples from the table are present therein. Columns may be added to the materialized view to contain pre-computed results of complex expressions, and indices may be created on the columns of the materialized view.

Abstract: A method, apparatus, and article of manufacture for simplifying and optimizing queries involving GROUP BY operations, when GROUP BY items involve constants and when there are “false” predicates in SELECT-HAVING clauses.

Abstract: Query evaluation is optimized using parallel optimization techniques to make repartitioning more efficient. Efficiency is improved by recognizing the possible partitioning requirements for achieving parallelism for a query operation, and by recognizing when the partitioning property of data satisfies the partitioning requirements of a query operation. A data base management system in accordance with the invention uses parallel query processing techniques to optimize data repartitioning, or to avoid it altogether.

Abstract: A database system and method provide support for a positioned data set modification operation on a collection of data sets involved in a data set query operation, in which the data set modification operation is based on the position of a query execution iterator. At query compile time, the database system generates an iterator position retrieval function and a data set modification function for each data set involved in the query operation. At query execution time, the database system invokes each of the iterator retrieval functions until the iterator position retrieval function for a current open data set returns the current the position of the query execution iterator on that data set. The database system then invokes each of the data set modification functions until the data set modification function for the current open data set performs a data set modification operation at the current position of the query execution iterator specified by the iterator position retrieval function.

Abstract: An automated methodology, and an apparatus for practicing the methodology, which enables the power and flexibility inherent in shared nothing parallel database systems (MPP) to be utilized on complex queries which have, heretofore, contained query elements requiring local computation or local coordination of data computation performed across the nodes of the distributed system. The present invention provides these features and advantages by identifying and marking the subgraphs containing these types of query elements as "no TQ zones" in the preparation phase prior to optimization. When the optimizer sees the markings, it builds a plan that will force the computation of the marked subgraphs to be in the same section. This preparation phase also provides the partitioning information for all inputs to the "no TQ zones". This allows the bottom-up optimizer to correctly plan the partitioning for the "no TQ zones".