Abstract: A method and system for distributing tasks from an external application among concurrent database application server instances in a database system for optimum load balancing, based on consensus among the instances. Each application instance identifies a task partition ownership by those in a membership group based on a time window and generates a new membership group and partition ownership based on the current partition ownership. The instance makes the new membership group and partition ownership known to other members by recoding them in the membership table and partition map. Each participation by an instance in the membership group is identified by a random number. The new membership group and partition ownership are generated and adjusted based on an average partition allocation to achieve consensus among the instances.

Abstract: Provided are techniques for, in response to a source object being changed by a local transaction, generating log records, wherein each of the log records includes a sequence identifier, a source system entity modification timestamp, a target key, a target partition identifier, and values of source properties, wherein the source properties are identified using a target key indicator. The log records to process are selected based on a phase value of each log record, wherein the phase value is one of submitted, in-flight, and source system entity state change complete. One or more disjoint partitions are assigned to each of multiple processing instances. Under control of each of the multiple processing instances, it is determined whether to transmit a log record in the one or more disjoint partitions assigned to said processing instance and, in response to determining that the log record is to be transmitted, the log record is transmitted.

Abstract: Systems, methods and articles of manufacture are disclosed for synchronizing a primary data system with an auxiliary data system that processes data for the primary data system. In one embodiment, how current the primary data system and the auxiliary data system are may be determined. Requests sent from the primary data system that were not processed by the auxiliary data system may be determined. The requests may be resent to the auxiliary data system for processing.

Abstract: Systems, methods and articles of manufacture are disclosed for managing availability of a component executing in a distributed system. The component may have an address space closed to the distributed system. In one embodiment, the component may be initiated. A state of the component may be analyzed to determine the availability of the component. The determined availability may be transmitted to the distributed system. The component may also be restarted responsive to a request from the distributed system to restart the component.

Abstract: A system for limiting the amount of time for a database server to perform a crash recovery process. A maximum recovery time for the database server to perform the crash recovery process is specified. An estimated recovery time for the crash recovery process that is less than the maximum recovery time is calculated, based on at least one of a deterministic analysis of cost accumulation during prior instances of the crash recovery process or an empirical analysis of cost accumulation during regular transaction processing in the database server. The crash recovery process is then conformed to the estimated recovery time.

Abstract: A method and system for supporting a concurrent recordation of a change in a data file by a server while allowing an application to continue writing changes to a data file. In response to a change in a data file, a near-instantaneous version of the file is created. Metadata reflecting the change to the data file are synchronized with a version of the file in cache and recorded in persistent storage. During the process of recording metadata changes to the file, subsequent changes to the data file may continue, and metadata reflecting the changes may be recorded in a subsequent near-instantaneous version of the file which may also be synchronized with a version of the metadata in persistent storage.

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.

Abstract: A method and apparatus are provided for dynamically improving the quality of service in a file or block serving system through assessing initial service quality, altering the service grade or priority of a selected resource handle, assessing a modified service quality impacted by that alteration of the resource handle service grade, and adjusting the resource handle service grade in response to the modified service quality. Alteration of the service grade may be achieved through intentionally imposing latency on the transactions associated with the selected resource handle. Alternately, the service grade alteration may result from randomly changing the priority ranking or service priority of the selected resource handle, thereby impacting the processing of the I/O transactions. The method and apparatus may be implemented at the back, or service end, of the system within the data storage sub-system, independent from and transparent to host and network awareness.

Abstract: Techniques for managing memory buffers include maintaining a pool of buffers and assigning the buffers to buffer classes based on the frequency with which information stored in the buffers is accessed. Different algorithms can be used to manage buffers assigned to the different classes. A determination can be made as to whether a particular buffer qualifies for entry into a particular one of the buffer classes based on a comparison between a threshold value and the frequency with which information stored in the particular buffer was accessed during a specified time interval. Additionally, the threshold value can be adjusted dynamically to take account, for example, of the current load on the system.