International Business Machines Corporation

Steven John Watts

Balakrishna Raghavendra Iyer

James C Kleewein

Tina Louise Mukai

Atul Chadha

Robert William Lyle

Hui-I Hsiao

Eileen Tien Lin

Stefan Bengt Edlund

Donald J Haderle

Akira Shibamiya

Joshua W Hui

Hemant Maheshwari

Yun Yu Wang

Ronald Jason Barber

Chandrasekaran Mohan

Julie Ann Watts

Piyush Goel

Josephine Miu Cheng

Shivakumar Venkataraman

HongHai Shen

Amit Radheshyam Somani

Venkatachary Srinivasan

Markos Zaharioudakis

Tu-An Cheng

Tony Kuen Lee

David Mark Herbert

Vaishnavi Anjur

Exemplary embodiments of the present invention relate to methodologies, computer program products and systems for the support of content replication, wherein transaction-level data replication consistency is guaranteed. Further, the exemplary methodologies of the present invention can be implemented while incurring little or no additional I/O overhead.

Transaction consistent content replication

Methods and computer program products for transaction consistent content replication

A technique for undoing a transaction that changes data in a database. In accordance with the present invention, the database contains at least one data unit. The database is stored in a data storage device connected to a computer. A lock, transaction identifier, transaction operation indicator, and data unit, are associated with the transaction. The invention undoes the transaction using the associated lock, transaction identifier, transaction operation indicator, and data unit.

Providing transaction undo without logging

A method, apparatus, and article of manufacture for providing transaction control for a computer-implemented database management system. The database management system manages one or more databases, wherein each of the databases contains one or more documents and each document contains one or more objects. The database management system also supports a file cache for those databases. A transaction control system provides transaction control for the databases, documents, and objects managed by the database management system, wherein the transaction control system monitors and controls the file cache to ensure that modified objects are stored on a data storage device in manner that reflects an accurate status for a log file maintained by the transaction control system.

Data recovery in a transactional database using write-ahead logging and file caching

A database management method enables an improved efficiency processing action in a computer wherein manipulation of data from a table is required in accord with a query request, wherein the table is stored remotely from said computer and at least some data in the table includes large data objects (LOBs). The method includes the steps of: responding to the request by transmitting a query to the table; configuring a result set from the table in response to the query, wherein the result set includes one or more unique identifiers of any LOB data associated with the result set; receiving the result set and performing a data manipulation action on data contained in the result set to form a response; transferring the response to the query requester; and accessing LOB data from the table that is referenced by the one or more unique identifiers in the result set and causing transfer of the LOB data to the query requester.

Method and apparatus for deferring large object retrievals from a remote

Many web applications require access to a relational database. The requirements of such web applications are different from conventional applications that access a database. Web applications need to have selective recoverability and need to have support for different transaction structures, other than the flat transaction structure of conventional database applications, including nested and chained transactions. To achieve this, an interface between the application and database has the following functional features: 1) the interface to the database is connection oriented, i.e., the connection is retained across several invocations of the application; 2) the backend of the interface is long living, i.e., it exists across multiple invocations; 3) state information about a session in progress is maintained, and more specifically, it is distributed between the backend of the interface and the hidden fields of the HTML output document.

Interface to support state-dependent web applications accessing a

A heterogeneous database system is described which includes plural database systems, one of the database systems acting as an interface (i.e., system manager). The system manager performs functions which provide an application program with transparent access to the entire database system. The system manager includes a memory for storing (i) a matrix of functional capabilities of each of the plural databases, (ii) a catalog of functions that are supportable by various databases and (iii) and entry matrix for providing an interface function between a user and the system manager. A processor is present in the system manager; and is responsive to a user entry, via the entry matrix, with respect to a functional capability of one of the plural databases, to alter a matrix of functional capabilities pertaining to the database. The alteration is carried out in accordance with a corresponding functional capability entry in the catalog. If a user entry is received which refers to a database for which no entry exists in the matrix of functional capabilities, the system manager presents an entry matrix in a form which reflects default functional capabilities. Thereafter, the default capabilities may be altered by a system administrator to reflect the capabilities of the new database.

Heterogeneous database system with data source extensibility and

In a distributed database system, at least one of the databases operates as a transaction manager and provides transparent commit coordination between an application program and other connected databases. The transaction manager incorporates a commit alteration procedure which enables selection of either a single phase commit protocol or a two phase commit protocol with respect to each database, during operation of the distributed system. The transaction manager establishes a commit protocol for each connected database; responds to a command from an application program by overriding a commit protocol previously established for a selected database and establishes another commit protocol for the selected database; performs a transaction and utilizes the another commit protocol in connection with the transaction; and upon completion of the transaction as evidenced by a successful commit action, enables establishment of another commit protocol.

Heterogeneous database system with dynamic commit procedure control

A method enables a computer to manipulate data from a table in a remote database in accord with a query from a query requestor, wherein at least some data in the table includes large data objects (LOBs). The method includes the steps of: responding to the query by configuring a database query and determining (i) if a response to the database query requires transfer of LOB data from the table and if yes, and (ii) the LOB data can be transferred in response to the database query without a data manipulation which uses the LOB data or (iii) a data manipulation required in response to the database query which uses the LOB data can be performed at the remote database, then designating the LOB data for 'streaming'; dispatching the database query to the remote database and receiving a result set from the table from the remote database in response to the query; and storing the result set and causing any LOB data which has been marked for streaming to be then dispatched to the query requestor without being written to disk.

Method and apparatus for accessing of large object data segments from a

A method, apparatus, and article of manufacture for providing access to information stored in a database management system. The method and apparatus uses an intelligent generic query agent to operate with a wide variety of remote users, and to allow implementation of a wide variety of optimization schemes. The method comprises receiving a request from the remote user at the agent, transforming the request into database management system commands optimized in accordance with user-specified optimization criteria, transmitting the database management system commands to the database management system, receiving the database management system command result from the database management system in the agent, transforming the database management system command result into a response message, and transmitting the response message to from the agent to the remote user.

Generic SQL query agent

The present invention provides a system and method for utilizing the proximity of keys in sequential or near sequential index probes to avoid complete index tree traversal. Page information from three pages (LAST, PARENT and NEXT) are stored in separate information fields within an Index Lookaside Buffer. The LAST information field contains information on the most recent leaf page accessed during an index probe in a read key or an insert key operation, the PARENT information field contains information on the parent page of the most recently accessed leaf page described in the LAST information field, and the NEXT information field contains information on the most recent leaf page accessed during a fetch-next key or delete key operation. On a subsequent index probe, the LAST, NEXT and PARENT information fields are sequentially analyzed to determine if the search key is contained within the leaf page described by the LAST or NEXT information fields or if the search key is contained within one of the leaf pages pointed to by the parent page described by the PARENT information field. If none of the LAST, NEXT or PARENT information fields identify the leaf page containing the search key then the default root-to-leaf traversal would commence.

Computer program product for avoiding complete index tree traversals in

System and method for avoiding complete index tree traversals in

The present invention provides a system and method for the dictionary ordering of keys after expansion, compression and concatenation of their key parts. After each key part has been expanded through padding, each substring of identical characters of length greater than or equal to three is compressed through run-length encoding algorithm. The substring is replaced by the sequence character, a compression identifying character and a number identifying the number of characters being replaced. After compression and the subsequent concatenation, the keys are compared character by character. At the first instance of a miscomparison, the comparison scheme performs a normal dictionary ordering if neither of the characters are part of a compression sequence. If a character at the point of miscomparison is part of a compression sequence then an ordering decision is made based on the compression character, the length of the compressed substring and the character following the compressed substring.

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Morgan Hill, CA, United States of America

Steven John Watts