International Business Machines Corporation

Roger L Q Zheng

Xun Xue

Steven Robert Pearson

Matthew Albert Huras

Richard Sefton Sidle

Adam J Storm

Chandrasekaran Mohan

Garret Frederick Swart

Michael Jeffrey Winer

James John Seeger, Jr

Kevin James Cherkauer

Catherine Suzanne McArthur

Effi Ofer

James Liam Finnie

Walter Duke Alvey

Gopi K Attaluri

Jason Christopher Young

Keriley Kay Romanufa

Jeffrey James Goss

Bruce M Jackson

Piotr M Plachta

Yuke Zhuge

Stewart L Palmer

Mark Dennehy

Kirill Bogdanov

Lorysa M Meadowcroft

Diarmuid Flynn

Marzia Mura

Ronen Grosman

Aamer U Sachedina

Scott David Lashley

Dale Murray McInnis

Miroslaw Adam Flasza

Quanhua Hong

Sarah Posner

Shaun K Thornborough

Techniques for data replication from a primary system to a standby system. A first buffer portion of a transaction log buffer is allocated to a first transaction at a primary system. Upon determining that the first buffer portion is fully formed, before the log data is written to the storage on the primary system, and before the transaction log buffer is entirely full, the log data in the first buffer portion is transmitted to the standby system, from the primary system. Upon writing the log data to the storage on the primary system and after the log data in the first buffer portion is transmitted to the standby system, a notification is transmitted to the standby system, from the primary system, where the standby system is configured to process the received log data responsive to receiving the notification from the primary system.

Log-shipping data replication with early log record fetching

Provided are techniques for using parallel inserts to insert into a column store. A list of sub-ranges for a columnar table is created. A change statement for one or more rows to be inserted into the columnar table is received. For each of the received change statements, a sub-range from the list of sub-ranges is identified and data is serially inserted into the identified sub-range of the columnar table, while allowing parallel processing of each change statement for different sub-ranges of the columnar table.

Using parallel insert sub-ranges to insert into a column store

Data integrity is maintained during failed communications between a member node of a primary cluster and a backup cluster by assigning an assisting member node to run an assisting process that transmits data entered into the member node to the backup cluster. In this way, a replicated database is maintained during a partial communication failure between the primary cluster and the backup cluster.

Handling failed cluster members when replicating a database between clusters

In a shared data system comprising one or more primary nodes and a plurality of secondary nodes, global lock manager on a primary node manages locks for shared resources by exchanging an abstract lock state with local lock managers on the secondary nodes. The abstract lock state includes a particular representation of all of the applications on the nodes that are requesting or are granted locks. The exchange of these particular lock states instead of individual requests improves performance by increasing concurrency and reducing off-machine communication. A global deadlock detector on a node detects and resolves global deadlocks, in conjunction with local deadlock detectors on the secondary nodes.

Two-level management of locks on shared resources

Methods, systems and program products for log-shipping data replication from a primary system to a communicatively-coupled standby system. Embodiments of the invention may receive transactional log data at a standby system, from the primary system, and before the transactional log data is written to storage on the primary system. Embodiments may then receive a notification from the primary system indicating that the corresponding log data was written to storage on the primary system, and responsive to receiving the notification, may process the received transactional log data.

Lock communications in a shared disk database system is reduced by several approaches: sending a single message to a lock manager for locks required for an operation and locks that will be required in the future, the operations may include row update, row delete, large scan, and row insert; performing an operation in two executions, where in a first execution locks required for the operation is determined without performing the operation, and in a second execution a single message is sent to a lock manager for the required locks and the operation is performed; in free space searching, sending a single message to a lock manager for row and page locks before a row insert is actually performed; and granting locks in an unfair manner.

Approaches to reducing lock communications in a shared disk database

A method and system are provided for providing a consistent reintegration of a failed primary instance as a new secondary instance with implementation of truncation of log records. Upon failure of a primary instance, a secondary instance may be reassigned as the new primary instance. Prior to reintegration, any portion of the database log of the failed primary that is after the log position of the new primary instance may be truncated, followed by a comparison of the log positions of both the new primary instance and the new secondary instance. In limited circumstances, the truncation of the log data generated by the failed primary instance after the point of failure is possible, and supports reintegration of the failed primary as a new secondary instance with limited overhead.

Consistent reintegration of a failed primary instance

A memory buffer facilitates log catchup for online operations. Certain designated areas of memory are allocated for one or more buffers for use during online operations (e.g., reorganization, create index, etc.). Concurrent update activities to the target object write informational records into the one or more buffers. If the buffers become full, the informational records may be written to logs for persistent storage. After online operations finish building all or a suitable portion of the shadow object, log catchup is performed by first applying activities in the informational records from the buffer and thereafter applying activities from logs, if necessary. The invention helps solve the drawbacks of log catchup since the buffer contains only the information related to the target shadow object. Also it does not involve physical I/Os, as these records are all in memory.

System and method for using a buffer to facilitate log catchup for online operations

A method and system for suspending log-based updates to a database in a manner that permits resumption of log-based updating without reinitializing the database. The method and system thereby permit efficient alternation between a log-based update mode and a database access mode. Unplayed log records are protected as revisions of database pages at the time that the log-based update was suspended. This approach permits log-based updating to resume at the same point at which log-based updating was suspended. In order to ensure consistent data for access while in database access mode, a roll-back procedure creates consistent data pages that are used for access and discarded when log-based update resumes.

Method and apparatus for interrupting updates to a database to provide read-only access

A system and method handle resource transaction requests. The system marks a waiting transaction request, having an access mode which is incompatible with the access mode of the executing transaction, with an ignore bit, so that a transaction request with an access mode compatible with the access mode of the executing transaction may receive a lock in order to access the resource. The transaction request is then marked with a bypass indicator such that when the executing transactions are finished accessing the resource, the waiting transaction request may be notified that it may have access to the resource. The system includes the ignore bit so that each transaction request that arrives after the ignore bit has been set, does not suffer from a long waiting time before being provided access to the resource.

System and method for handling resource transaction requests

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Richmond Hill, Canada

Roger L Q Zheng