International Business Machines Corporation

Paraccel LLC

Red Brick Systems, Inc.

David G Wilhite, Jr

Latha S Colby

William McKenna

Richard Lee Cole

Galt Johnson

Nasi Jazayeri

Edward P Haslam

Lee E Schumacher

Mayank Pradhan

Robert P Desantis

Adam Birnbaum

Raymi Dyskant

David Benedict Galimberti

Velimir Radanovic

Brian Pak-Ning Chu

Craig J Bunger

Mandar S Pimpale

Gopal B Mulagund

William J McKenna

A logical backup of a database is performed that allows physical properties of the database to be preserved upon restore. The physical properties of the database include properties related to storage of the data on the hard disk. Preserving the physical properties of a database allows performance debugging of the source database by performing performance tests on the target database rather than a production system. Incremental backup of metadata of a database is performed to minimize execution of statements that provide the final configuration of the database. Incremental backup is performed by restoring a database using a full backup and applying incremental backups to reach a particular state. The user can inspect the restored database after applying each incremental backup to determine whether the database has reached a desired state.

Backup and restore of databases

A database system performs hash join process for processing queries that join an inner and an outer database table. The hash join processes builds a hash table in memory for the inner table. The database system receives a limit on the memory for storing the hash table. The database system maximizes the number of partitions stored in memory for the hash table. If the hash table exceeds the limit of the memory while adding rows from the inner table, the database system selects a partition for spilling to a persistent storage. The partition selected for spilling to may be the largest partition or a partition larger than most of the partitions. The database system initializes the hash table to a number of partitions that is substantially equal to half of the total number of blocks that can be stored within the specified limit of memory for the hash table.

Disk-based hash join process

Systems, methods and articles of manufacture are disclosed for generating a relational database query from an online analytical processing (OLAP) query against a cube. The cube may have dimensions, each dimension having a hierarchy of members. A level of the hierarchy of a dimension of the cube may be identified from which the OLAP query accesses a number of members exceeding a predefined threshold count of members. A relational database query may be generated that includes a predicate for at least one member from at least one level above the identified level in the hierarchy, instead of a plurality of predicates for members from the identified level. The relational database query may be generated from the OLAP query, from a definition for the hierarchy, and from the accessed members from the identified level. As a result, the relational database query may include fewer predicates and may be executed more efficiently.

Generating query predicates for processing multidimensional data

Technique are provided for maintaining pre-computed aggregate views. A pre-computed aggregate view derived from one or more base tables is received, the pre-computed aggregate view including a pre-computed aggregate table and a view definition, the view definition including aggregate functions that can be any combination of sum, sum distinct, count(*), count, count distinct, min, and max, the view definition further including expressions that may be nullable. Changes to the one or more base tables are received, the changes being represented as insertions and deletions and being non-minimal. A set of incremental modifications to the pre-computed aggregate table are derived and applied based on the changes to the one or more base tables, wherein modifications may include any combination of inserts, deletes, and updates. Deriving the set of incremental modifications to the pre-computed aggregate table includes deriving a first table wherein each record, representing an aggregated group of changes, shows for each aggregation function, the contributions of base table changes that are insertions for the group and the contributions of base table changes that are deletions for the group and using some combination of information in the first table, the pre-computed aggregate table, and the one or more base tables from which the pre-computed view is derived.

Maintaining pre-computed aggregate views incrementally in the presence of non-minimal changes

Methods and apparatus implementing a technique for incrementally maintaining pre-computed aggregate views. In general, the technique includes: receiving a pre-computed aggregate view derived from one or more base tables. The pre-computed aggregate view including a pre-computed aggregate table and a view definition. The view definition including aggregation functions that can be any combination of sum, sum distinct, count(*), count distinct, min, and max. The view definition further including expressions that may be nullable. The technique includes receiving changes to the base table, the changes being non-minimal. The technique includes analyzing the view definition, including the type of aggregation functions and the nullability and data type of columns and expressions in the view definition, to reduce or eliminate the use of information in base tables in order to define the incremental modifications to the pre-computed aggregate table.

A system and method for answering a relational database query is presented. According to an embodiment of the present invention, a database query is received. It is then determined whether that query can be rewritten in such a manner as to be able to utilize a precomputed view, such that an answer to the rewritten query is equivalent to an answer to the original query. If the query can be rewritten, it is determined whether the rewritten query can more efficiently derive the answer than the original query. The query which has the most efficiently derived answer is the query which is utilized to derive that answer.

System and method for rewriting relational database queries

Server-integrated methods and apparatus for processing precomputed views for answering user queries on a database are described. In accordance with one embodiment, a system for answering user queries on a database stored on a server includes a query processing system integrated into the server and configured to respond to user queries, and a query processing system integrated into the server and configured to process precomputed results of user queries on the database. In another aspect, a method of answering user queries on a database stored on a server includes responding to user queries received at the server, and processing, at the server, precomputed results of user queries on the database.

Server integrated system and methods for processing precomputed views

Methods and apparatus for processing precomputed views for answering user queries on a database are described. In accordance with one aspect, a user database query on precomputation strategy effectiveness is responded to by defining, based upon user database query history, an analysis space consisting of a subset of all possible views for the database, and by characterizing the views in the analysis space. In accordance with a second aspect, a structure is imposed on an analysis space consisting of a subset of all possible views for the database based upon the capabilities of a query rewriting facility, and the views in the analysis space are characterized. In accordance with a third aspect, an analysis space consisting of a subset of all possible views for the database is defined, and a cost formula is applied to the analysis space based upon a user-defined subset of the data contained in the database. In accordance with a fourth aspect, an analysis space that includes a candidate view composed of a combination of two or more constituent views is defined, and the views in the analysis space are characterized.

Defining and characterizing an analysis space for precomputed views

The invention features methods and apparatus for processing precomputed views for answering user queries on a database. In accordance with one aspect, a user query on the database is analyzed, and a candidate view based upon the user query is generated.

System and method for determining and generating candidate views for a database

A system and a method maintain a precomputed view corresponding to detail data in a database server by: determining a maintenance plan to refresh the precomputed view when detail data is changed; integrating the maintenance plan with a query execution plan in the database server; and executing the query execution plan.

Growing community of inventors

Santa Clara, CA, United States of America

David G Wilhite, Jr