Abstract: A method and mechanism are provided for creating, maintaining, and using a hierarchical index to efficiently access information in a relational system based on a pathnames, thus emulating a hierarchically organized system. Each item that has any children in the emulated hierarchical system has an index entry in the index. The index entries in the index are linked together in a way that reflects the hierarchical relationship between the items associated with the index entries. Pathname resolution is performed by following direct links between the index entries associated with the items in a pathname, according to the sequence of the filenames within the pathname. By using an index whose index entries are linked in this manner, the process of accessing the items based on their pathnames is significantly accelerated, and the number of disk accesses performed during that process is significantly reduced.

Abstract: A method and apparatus are provided for transferring a resource from the cache of one database server to the cache of another database server without first writing the resource to disk. When a database server (Requestor) desires to modify a resource, the Requestor asks for the current version of the resource. The database server that has the current version (Holder) directly ships the current version to the Requestor. Upon shipping the version, the Holder loses permission to modify the resource, but continues to retain the resource in memory. When the retained version of the resource, or a later version thereof, is written to disk, the Holder can discard the retained version of the resource. Otherwise, the Holder does not discard the retained version. Using this technique, single-server failures are recovered without having to merge the recovery logs of the various database servers that had access to the resource.

Abstract: A method and apparatus are provided for transferring a resource from the cache of one database server to the cache of another database server without first writing the resource to disk. When a database server (Requestor) desires to modify a resource, the Requestor asks for the current version of the resource. The database server that has the current version (Holder) directly ships the current version to the Requestor. Upon shipping the version, the Holder loses permission to modify the resource, but continues to retain the resource in memory. When the retained version of the resource, or a later version thereof, is written to disk, the Holder can discard the retained version of the resource. Otherwise, the Holder does not discard the retained version. Using this technique, single-server failures are recovered without having to merge the recovery logs of the various database servers that had access to the resource.

Abstract: Techniques are provided for updating data that logically resides in one or more nested collections in a nested collection column of a view. According to one technique, a Data Manipulation Language (DML) statement that operates on individual elements within the one or more nested collections is detected. Instead of executing the DML statement, trigger code is executed once for each individual element, within the one or more nested collections, that is targeted by the DML statement. In addition, the trigger code may include one or more references to parent values. For each nested collection selected by the DML statement, the following steps are performed when the trigger code includes references to parent values: determining the row, within the view, in which the nested collection resides and, prior to executing the trigger code for the nested collection, binding the one or more references to one or more corresponding values that logically reside in the row.

Abstract: A method and apparatus are provided for transferring a resource from the cache of one database server to the cache of another database server without first writing the resource to disk. When a database server (Requestor) desires to modify a resource, the Requestor asks for the current version of the resource. The database server that has the current version (Holder) directly ships the current version to the Requestor. Upon shipping the version, the Holder loses permission to modify the resource, but continues to retain the resource in memory. When the retained version of the resource, or a later version thereof, is written to disk, the Holder can discard the retained version of the resource. Otherwise, the Holder does not discard the retained version. Using this technique, single-server failures are recovered without having to merge the recovery logs of the various database servers that had access to the resource.

Abstract: A method and apparatus are provided for extending the behavior and attributes of applications designed using a fourth generation language (4GL) programming tool. Specifically, a 4GL programming tool is provided that allows application designers to specify the implementation classes of the components that are used in the applications that they design using the 4GL programming tool. The implementation classes thus specified may define attributes and behaviors not supported by the corresponding component implementations provided with the 4GL programming tool. During runtime, methods in the specified implementation classes are invoked. To correctly invoke the methods of user-specified implementation classes, the interfaces of the methods must be known to the entity performing the invocations.

Abstract: Methods are provided for communicating with and regulating access to a storage system contained within a file system. Storage access keys are used to communicate to the file system changes in location of data stored in the storage system. Fence keys are used to regulate access to the storage system.

Abstract: An intelligent approach for performing administrative functions generally involves performing a set of administrative function steps within a “maintenance window” that is defined by one or more specified time periods. First, a set of administrative function steps to be performed are identified. The set of administrative function steps is prioritized to produce a set of prioritized administrative function steps. Then, the set of prioritized administrative function steps is performed during the maintenance window. Aspects and features of the invention include: identifying and prioritizing administrative function steps; estimated function times and maintenance window; failure prediction; environment recommendations; history information and learning techniques; saving state and context information; and user feedback.

Abstract: A task is divided into work granules that require access to data objects. The work granules are distributed to slave processes in a manner that causes the data objects to be accessed in a balanced way, such that the difference in the number of slave processes accessing any object is not greater than one. Distributing the work granules in this manner decreases the likelihood that the resources required to access any particular data object will become a bottleneck in performing the task. For each data object in the set of data objects, a work granule list is maintained. The list of each data object identifies work granules requiring access to the data object. A slave process is assigned a work granule selected from a set of work granule lists. To select a work granule for a slave process, an initial list is picked at random.

Abstract: A method and apparatus are provided for managing the amount of memory available to processes within the computer system. Additional virtual address spaces are dynamically created to make more memory available to computer processes. The computer processes executing in each virtual address space access a shared memory region. Also, when a user requests a new connection to the computer system to form a new user session, it is determined to which of the existing virtual address spaces the new user session would best be assigned so as to maintain a load balance among the existing virtual address spaces.

Abstract: Techniques for managing files in a computer system are provided. According to one technique, an association is established between a type of file system operation, a file, and an interested entity. It is detected when that type of file system operation is performed on the file. In response to detecting that that type of file system operation is performed on the file, a message is sent to the interested entity.

Abstract: Provided are mechanisms that may be used to support efficient exportation of user data stored in a database system. According to an aspect of the present invention, a database system is configured to store data for users in separate repositories referred to as tablespaces. To store data in this manner, a database system may be configured in variety of ways.

Abstract: A method and mechanism is provided for executing a query that includes a subquery, where the subquery includes an ORDER BY clause. The results generated by executing the subquery are ordered as specified by the ORDER BY clause. When the results of the subquery are referenced by the outer query, the results generated for the subquery satisfy the restriction. For example, the restriction may specify that the row number pseudo-column be less than a threshold. In response, a TOP N operation is performed to return the rows that are TOP N in order. The order is based on the ORDER BY clause.

Abstract: A hierarchy may be explicitly or implicitly reflected in existing data maintained external to hierarchy structures. Such hierarchies are referred to herein as a “pre-existing hierarchies”. Techniques are described herein for capturing a pre-existing hierarchy in hierarchy structures. After a pre-existing hierarchy has been captured, there exist two independent sets of data that reflect the hierarchy: the external hierarchy definition and the internal hierarchy definition. Changing either hierarchy definition changes the hierarchy. Therefore, to maintain a consistent reflection of the hierarchy, the internal hierarchy definition must be modified in response to changes made to the external hierarchy definition, and the external hierarchy definition must be modified in response to changes made to the internal hierarchy definition. Various techniques are described for maintaining consistency between the two hierarchy definitions.

Abstract: Disclosed is a method and mechanism for sizing a hardware system for a software workload. An aspect is directed to modeling a workload into a set of generic system activities, in which the generic system activities are not directly tied to a specific hardware platform. Another aspect is directed to profiling hardware systems or hardware components into the generic system activities. Suitable hardware systems or components are selected by analyzing the workload and hardware profiles in terms of the generic system activities.

Abstract: A method and mechanism is described for reliably transmitting messages over an unreliable transport mechanism. A sender transmits a first message over an unreliable mechanism to a receiver, and a second message that identifies the first is transported over a reliable transport mechanism to the receiver. When the receiver receives the second message, the receiver determines whether it has received the first message. If not, the receiver requests retransmission of the first message.

Abstract: A novel locking approach for managing access to resources generally includes generating and storing duplicate lock data that may be used if the original lock data upon which the duplicate lock data is based is lost or otherwise becomes unavailable. In response to granting a lock on a resource to a first process, lock data is generated that indicates that the lock on the resource was granted to the first process. Duplicate lock data is generated that indicates that the lock on the resource was granted to the first process. When a change is made to the lock data, the duplicate lock data is updated to reflect the change made to the lock data. If the lock data is lost or otherwise becomes unavailable, the duplicate lock data may be used to continue managing access to the resource.

Abstract: Techniques are provided which address the problems associated with the conventional approaches for storing multidimensional data in a relational database system. According to technique, the many foreign key values of each row in the fact table are mapped to and replaced by a “replacement” value. A mapping function is provided that derives a replacement value from any given combination of foreign key values, and an inverse mapping function is provided to reproduce the combination of foreign key values given the replacement value. A mapping function is selected such that the foreign key value combinations of multidimensional values that are conceptually related to each other map to values that are close to each other. The rows in the fact table are then stored within the fact table in the sorted order, thus causing values that are conceptually related to each other to be stored physically near each other within the fact table.

Abstract: The present invention relates to a method of processing data files which are generated in accordance with different protocols. Each protocol defines a number of mark-up tags and each data file includes a number of respective mark-up tags, each mark-up tag having respective data associated therewith. The method including storing the data contained in a data file by receiving the data file, determining the protocol definition, and using the protocol definition to determine storage location(s) or processing action(s) for each of the mark-up tags of the data file. Once this has been done the protocol definition is used to determine contextual information for each of the mark-up tags of the data file. The marked up data contained within the data file is then extracted and, stored or processed in accordance with the determined contextual information and at least one of the storage location(s) or the processing action(s).

Abstract: Techniques for optimizing a distributed lock manager (DLM) for faster reconfiguration includes distributing over a cluster of one or more active nodes, management of locks on shared resources. A system hash map is initialized to establish a mapping between a plurality of hash value ranges and one or more master nodes. The management of the locks is initially distributed based on that mapping. The cluster is monitored to gather data during a time interval, including data that identifies how much resource usage is made of resources hashed to each hash value range of the plurality of hash value ranges. It is determined whether a re-mastering event condition is satisfied based on one or more factors. The factors include the resource usage. If the re-mastering event condition is satisfied, a re-mastering event is performed.