International Business Machines Corporation

Tuong Chanh Truong

Mir Hamid Pirahesh

David Everett Simmen

Ting Yu Leung

Roberta Jo Cochrane

Edison Lao Ting

Richard Sefton Sidle

Monica Sachiye Urata

Tian Zhang

George Lapis

Anjali Betawadkar-Norwood

Mayank Pradhan

Nisanth M Simon

Normen Seemann

Ruiming Zhou

Alex Chak-tsang Lui

Radhika Reddy

Calisto Paul Zuzarte

Sam Sampson Lightstone

Bruce Gilbert Lindsay

Serge Bourbonnais

Kevin Scott Beyer

Yao-Ching Stephen Chen

Michael Jeffrey Winer

Jyh-Herng Chow

Brian Thinh-Vinh Tran

Elizabeth Belva Hamel

John A McPherson, Jr

Nelson Mendonca Mattos

Robbert Van Der Linden

Henrik Loeser

Daniel J Coyle, Jr

Uttam Jain

Petrus Kai Chung Chan

Gene Y Fuh

Jeffrey D Richey

Chengfei Liu

Jens Stankiewitz

Embodiments of the present invention disclose a method, computer program product, and system for detecting changes in database schema. The embodiments may include receiving a first database schema. The embodiments may include creating a first value corresponding to the first database schema by utilizing a compressed value algorithm. The compressed value algorithm may create a single value corresponding to each database schema. The embodiments may include receiving a second database schema. The embodiments may include creating a second value corresponding to the second database schema by utilizing the compressed value algorithm. The embodiments may include determining whether there is a difference between the first database schema and the second database schema by comparing the first value and the second value.

Database comparison system

Embodiments are included for methods, systems, and computer program products in which evaluating operations using an electronic computing device are presented including: receiving the operation on a first database partition in a shared nothing parallelism system, where the operation is non-collocated, reference based operation; generating a correlation sequence, where the correlation sequence includes a sequence of references pointing to input data required for the operation; receiving one of the references on a first table queue operator on a second database partition, where the second database partition includes input data corresponding with the received reference, and where the table queue operator is configured for providing communication between the first database partition and the second database partition; and processing the input data on the second database partition corresponding with the operation.

Evaluating reference based operations in shared nothing parallelism systems

Embodiments are included for methods, systems, and computer program products for evaluating operations in a shared nothing parallelism system using an electronic computing device are presented, the methods and computer program products including: causing the electronic computing device to receive the operation, where the operation is non-collocated, reference based operation, and where the operation is configured for execution on a first partition in the shared nothing parallelism system; causing the electronic computing device to insert a table queue operator on a second partition, where the second partition includes a reference to input data, causing the electronic computing device to place the reference to the input data on the first partition by the table queue operator; and causing the electronic computing device to execute the operation on the reference to the input data on the first partition.

An apparatus and method for optimizing descendant path evaluation in XPath/XQuery includes generating a list of unique paths in a tree structure of an XML document. Each unique path includes one or more nodes of the tree structure. A query is received specifying a descendant node for retrieval from the tree structure. From the list, unique paths are identified that include the descendant node. A navigation aid is then generated to assist in traversing the unique paths that include the descendant node. Using the navigation aid as a guide, descendant nodes in the tree structure may be retrieved by traversing only unique paths that include the descendant node.

Apparatus and method for optimizing descendant path evaluation in xpath/xquery

A system and method is provided for processing XQuery Updates on an Extensible Markup Language (XML) document. The XQuery Updates are processed in three phases. The first phase includes creating a pending update list (PUL) including all update operations to be performed on nodes in a fragment of the Extensible Markup Language (XML) document. The second phase includes sorting the PUL. The third phase includes applying the sorted PUL to each node in the XML fragment during a single traversal of the XML fragment.

Three-phase single-pass efficient processing of Xquery update

An apparatus and method are disclosed for skipping XML index scans with common ancestors of a previously failed predicate. An XML index is scanned by an XML index scan to filter entries of the index matching at least one search value (predicate) of an XML query. When the XML index scan finds a matching entry, the entry is passed to an XPath evaluation component. The XPath evaluation component evaluates the entry against remaining predicates of the XML query for further qualification. When the XPath evaluation component disqualifies an entry, the XPath evaluation component provides feedback to the XML index scan to skip remaining entries comprising a common ancestor of the disqualified entry's path. The XML index scan can then efficiently skip index entries that will not qualify against the XML query.

Apparatus and method for skipping XML index scans with common ancestors of a previously failed predicate

Provided are a method, system, and program for merging independent log entries in a multiple node shared nothing DBMS. Initially, log entries from multiple log entries are combined to form a single log entry sequence. Local transactions are generated from the single log entry sequence and stored in a local transactions structure. In particular, log entries with the same local transaction identifier form a local transaction. Then, local transactions having the same global identifier are merged to form global transactions.

Method, system, and program for merging log entries from multiple recovery log files

An optimization technique for SQL queries, a program storage device storing the optimization program, and an apparatus for optimizing a query is provided. A query is analyzed to determine whether it includes a predicate for matching nullable operands and, if so, it is transformed to return TRUE when all operands are NULLs. If the DBMS supports this new function, the predicate is marked. If not, the predicate is re-written into a CASE expression having two SELECT clauses. The query is then executed in the computer to efficiently retrieve data from the relational database.

Method of optimizing SQL queries where a predicate matches nullable operands

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.

Parallel query optimization strategies for replicated and partitioned tables

An optimization technique for SQL queries, a program storage device storing the optimization program, and an apparatus for optimizing a query is provided. A query is analyzed to determine whether it includes the WHERE clause which contains an &ldquo;EXISTS&rdquo; subquery and a &ldquo;NOT EXISTS&rdquo; subquery, or EXISTS-equivalent subqueries, in Boolean factor. If so, the subsumption test is performed on two subqueries. Then, the compensation predicate is applied to one of them, to perform the QGM transformation of the query. One subquery block is stacked on top of the other subquery block, in order to eliminate one subquery. This procedure allows the transformed query to perform more efficiently than the original query while providing same results. The query is then executed in the computer to efficiently retrieve data from the relational database.

Method of optimizing a query having an existi subquery and a not-exists subquery

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.

System and method for selective incremental deferred constraint processing after bulk loading data

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. The system and method may be implemented on single node systems and on multi-node shared-nothing parallelism architectures.

Database system and method for supporting current of cursor updates and

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'. These partitionings can force the operation to a single-node, the coordinator node, the catalog node, or to a particular partition class on multiple nodes, or nodegroups.

Shared nothing parallel execution of procedural constructs in SQL

A relational data base management system includes a query processor that permits consideration of alternative query plans by the query optimizer so one table can be sent to a selected network location for subquery evaluation in consideration of maximum processing efficiency. Subqueries are converted from 'predicate push-down' form to scalar subqueries, enabling upper tables to be sent to nodes of lower tables and vice versa, thereby permitting selection of the node direction depending on the least cost alternative. The optimizer of the query processor is presented with rewritten query code that permits more than one alternative for sending tables for evaluation. The optimizer evaluates the alternatives permitted by the rewritten code, determines the optimal plan for each alternative, and selects the least-cost plan from among the plans evaluated. Thus, the optimizer can decide to send an outer table to where a subquery table is located, or can decide to send a subquery table to where an outer table is located, depending on which is more efficient.

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San Jose, CA, United States of America

Tuong Chanh Truong