Abstract: A mechanism is provided for multi-part aggregated variables in structured external storage. The shared external storage provides a serialized, aggregated structure update capability. The shared external storage identifies each local value for which a group value is needed by name. Each time a member writes out its value, the member specifies the name of the object, the member's current value, and the type of aggregate function to apply (e.g., minimum, maximum, etc.). The structured external storage in one atomic operation updates the member's value, recalculates the aggregate of all of the individual values, and returns the aggregate to the member. The advantage of this approach is that it requires only one write operation to the structured external storage. The update operation does not require locking, because the operation is atomic.

Abstract: 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.

Abstract: Embodiments of the present invention address deficiencies of the art in respect to programmatic database access and provide a method, system and computer program product for programmatic partial updating of a row. In one embodiment, a data processing system for programmatic partial updating of a row in a database can include a database proxy driver configured to expose an interface for interacting with the database and to accept an execution of a prepared statement without requiring set values for all fields bound by the prepared statement. The interface can include, for example, a Java Database Connectivity (JDBC) compliant interface. The prepared statement can include a binding to multiple fields in a designated row and a set of setter methods defined for a subset of the multiple fields.

Abstract: A software thread is dispatched for causing the system to poll a device for determining whether a condition has occurred. Subsequently, the software thread is undispatched and, in response thereto, an interrupt is enabled on the device, so that the device is enabled to generate the interrupt in response to an occurrence of the condition, and so that the system ceases polling the device for determining whether the condition has occurred. Eventually, the software thread is redispatched and, in response thereto, the interrupt is disabled on the device, so that the system resumes polling the device for determining whether the condition has occurred.

Abstract: A software thread is dispatched for causing the system to poll a device for determining whether a condition has occurred. Subsequently, the software thread is undispatched and, in response thereto, an interrupt is enabled on the device, so that the device is enabled to generate the interrupt in response to an occurrence of the condition, and so that the system ceases polling the device for determining whether the condition has occurred. Eventually, the software thread is redispatched and, in response thereto, the interrupt is disabled on the device, so that the system resumes polling the device for determining whether the condition has occurred.

Abstract: A coherency manager provides coherent access to shared data by receiving a copy of updated database data from a host computer through RDMA, the copy including updates to a given database data; storing the copy of the updated database data as a valid copy of the given database data in local memory; invalidating local copies of the given database data on other host computers through RDMA; receiving acknowledgements from the other host computers through RDMA that the local copies of the given database data have been invalidated; and sending an acknowledgement of receipt of the copy of the updated database data to the host computer through RDMA. When the coherency manager receives a request for the valid copy of the given database data from a host computer through RDMA, it retrieves the valid copy of the given database data from the local memory and returns the valid copy through RDMA.

Abstract: An ordering of operations in log records includes: performing update operations on a shared database object by a node; writing log records for the update operations into a local buffer by the node, the log records each including a local virtual timestamp; determining that a log flush to write the log records in the local buffer to a persistent storage is to be performed; in response, sending a request from the node to a log flush sequence server for a log flush sequence number; receiving the log flush sequence number by the node; inserting the log flush sequence number into the log records in the local buffer; and performing the log flush to write the log records in the local buffer to the persistent storage, where the log records written to the persistent storage comprises the local virtual timestamps and the log flush sequence number.

Abstract: 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.

Abstract: Provided are a method, system, and article of manufacture for the traversal of empty regions in a searchable data structure such as a table. A plurality of elements are allocated in logical storage, wherein the plurality of elements correspond to entries of the searchable data structure. An indicator is maintained corresponding to contiguously allocated empty elements in the plurality of elements. An operation is performed on the searchable data structure by avoiding the contiguously allocated empty elements.

Abstract: Performing a redistribute of data in a database system including a plurality of nodes is disclosed. The data includes a plurality of partitions distributed between the plurality of nodes. At least one new node is being added. At least one partition of the plurality of partitions is selected to be moved from the plurality of nodes only to the at least one new node. The at least one partition is moved only to the at least one new node. At least one partition is removed from the plurality of nodes.

Abstract: A method for performing a redistribute of data in a database system including a plurality of nodes is disclosed. The data includes a plurality of partitions distributed between the plurality of nodes. At least one new node is being added. The method and system include selecting at least one partition of the plurality of partitions to be moved from the plurality of nodes only to the at least one new node. The method and system also include moving the at least one partition only to the at least one new node. The method and system further include removing the at least one partition from the plurality of nodes.

Abstract: Embodiments of the present invention address deficiencies of the art in respect to programmatic database access and provide a method, system and computer program product for programmatic partial updating of a row. In one embodiment, a data processing system for programmatic partial updating of a row in a database can include a database proxy driver configured to expose an interface for interacting with the database and to accept an execution of a prepared statement without requiring set values for all fields bound by the prepared statement. The interface can include, for example, a Java Database Connectivity (JDBC) compliant interface. The prepared statement can include a binding to multiple fields in a designated row and a set of setter methods defined for a subset of the multiple fields.

Abstract: Provided are a method, system, and article of manufacture for the traversal of empty regions in a searchable data structure such as a table. A plurality of elements are allocated in logical storage, wherein the plurality of elements correspond to entries of the searchable data structure. An indicator is maintained corresponding to contiguously allocated empty elements in the plurality of elements. An operation is performed on the searchable data structure by avoiding the contiguously allocated empty elements.

Abstract: A method, apparatus and article of manufacture, implementing the method, accesses rows in a range-clustered table in a database management system. A table stores data that is organized into rows and columns. At least one column is designated as a key column. A particular row in the table is accessed based on a relationship between a specified key value and a predetermined range of key values associated with the key column. The table has slots for storing rows, and the slots are organized in accordance with the values of the predetermined range.

Abstract: A method, apparatus and article of manufacture, implementing the method, accesses rows in a range-clustered table in a database management system. A table stores data that is organized into rows and columns. At least one column is designated as a key column. A particular row in the table is accessed based on a relationship between a specified key value and a predetermined range of key values associated with the key column. The table has slots for storing rows, and the slots are organized in accordance with the values of the predetermined range.