Abstract: Techniques are provided for maintaining high propagation availability for non-persistent messages. Destination-to-instance mapping information is provided to a listener process for a cluster database. The destination-to-instance mapping indicates the current owner instance of each single-instance destination within the cluster database. To establish a connection to a single-instance destination, a sending process sends a connection request to the global listener. The connection request identifies the desired destination queue, but not the owner instance of the queue. The global listener for the cluster database uses the destination-to-instance mapping to determine which instance is the current owner of the specified queue, and establishes a connection between the sending process and the appropriate owner instance.

Abstract: Techniques are provided for managing electronic items by storing, within a file group repository, metadata that identifies (a) a plurality of file groups, (b) for each file group, a set of one or more file group versions for the file group, and (c) for each file group version of each file group, a set of one or more items that belong to the version of the file group. Once the metadata has been established, queries may be executed against the metadata to request identification of items that belong to a particular version of a particular file group. This file group framework may be used in a variety of contexts, including the management of a centralized tablespace repository, and periodic purging of versions of file collections, where the files within the collections may be spread across multiple repositories.

Abstract: A method and system are provided for instantiating objects for participation in information sharing relationships. According to one technique, a copy of an object is made, where the copy includes all changes made prior to a particular point in time, and no changes made after the particular point in time. The copy is used to create a second object. Data that reflects the particular point in time is stored, and subsequently used to determine which changes should be applied to the second object. Data that indicates that the creation time of the second object is stored, and subsequently used to determine which changes should be applied to the original object.

Abstract: Techniques for making a replica of a particular group of database objects of a database on a particular node that does not initially have the particular group of database objects include determining whether conditions for copying a full database from a first node are satisfied. If conditions for copying the full database from the first node are not satisfied, then a database-object-copy routine is employed for each database object in the particular group of database objects. If conditions for copying the full database from the first node are satisfied, then a full-database-copy routine for performing a copy of an entire database is employed.

Abstract: Techniques for making a replica of a particular group of database objects on a particular node of a network include receiving, during a transfer period, a first copy of the particular group of objects at the particular node from a first node on the network. The particular node receives, from a second node on the network, data indicating changes to the particular group of database objects on the second node, where the changes indicated in the data are changes that were made at the second node during the transfer period. The first copy of the particular group of database objects is modified based on the data indicating changes.

Abstract: A source database system sends information to a destination database system, and each database system generates a separate set of sequence information. A mapping is maintained between the two sets of sequence information. Using the mapping, the destination database system may be used to restore changes lost at the source database system without reinstating the source database. Additionally, queries associated with a particular point in a sequence associated with the sequence information of the source database may be redirected to the destination database, and the destination database system may serve as a logical standby for the source database system. A variety of methods of maintaining and/or extracting the mapping information are disclosed.

Abstract: An approach migrates database sessions from a database server on which performance and resource availability requirements are not being met to another database server. Because workload is removed from the database server not meeting these requirements, improved performance there is promoted. Furthermore, the approach switches the users in a way that attempts to keep performance and resource availability levels at the database server receiving the database sessions within goals for performance and resource availability.

Abstract: Approaches are used for efficiently and effectively managing the dynamic allocation of resources of multi-node database systems between services provided by the multi-node database server. A service is a category of work that is hosted on the database server. The approaches manage allocation of resources at different levels. For services that use a particular database, the performance realized by the services is monitored. Resources assigned to the database are allocated between these services to ensure performance goals for each are met. Resources assigned to a cluster of nodes are allocated between the databases to ensure that performance goals for all the services that use the databases are met. Resources assigned to a farm of clusters are assigned amongst clusters based on service level agreements and back-end policies. The approach uses a hierarchy of directors to manage resources at the different levels.

Abstract: An approach efficiently and dynamically allocates and de-allocates database instances and nodes between databases. The approach performs this function in a way that accounts for the users of and services hosted by multiple databases.

Abstract: Approaches described herein may be used for provisioning of databases that requires a bulk transfer of data within a distributed computing environment, such as a grid. The approaches do not require the manual intervention of a DBA to, for example, transfer a tablespace between the file systems of operating systems. Instead, the tablespaces may be provisioned automatically and dynamically by a grid computing system whenever it determines the need to dynamically provision a database. In addition, as copies of tablespaces are provisioned, synchronization mechanisms can also be automatically provisioned to keep the tablespaces and their copies in sync.

Abstract: An approach generates performance grades. A performance grade is a value or set of values that indicates the relative work performance offered by a resource, such as a server in a multi-node system, relative to other resources. Performance grades are used to dynamically allocate work within a multi-node computer system. For example, performance grades are used for connection-time balancing, and to direct a database connection request to a multi-node database instance that a performance grade indicates provides better performance. Performance grade deltas are generated that reflect the incremental change in performance grade for additional sessions or work. Performance deltas are used to direct incoming sessions, to more optimally balance workload, and to deal with logon storms where a large number of connect requests arrive in a very short time period.

Abstract: A method and system are provided for instantiating objects for participation in information sharing relationships. According to one technique, a copy of an object is made, where the copy includes all changes made prior to a particular point in time, and no changes made after the particular point in time. The copy is used to create a second object. Data that reflects the particular point in time is stored, and subsequently used to determine which changes should be applied to the second object. Data that indicates that the creation time of the second object is stored, and subsequently used to determine which changes should be applied to the original object.

Abstract: In some messaging system architectures, messages can cycle back to the originator of a message, who may then propagate the message, causing the cycle to be repeated. Described herein are techniques that use rules and fields in a redo log, to manage message flows such that undesired cycles are prevented. The techniques may be used in messaging systems that have various topologies.

Abstract: Described herein are various approaches that allow rules to be used to specify actions, that alleviate the complexity and burden of developing and maintaining rules in a rules-based messaging system, and that provide more efficient ways of evaluating rules. The approaches allow rules to specify user-defined transformation functions for transforming messages, to specify when and how to perform row migration, and to specify other types of actions. Rules are grouped into rule sets. Several types of rule sets, referred to as positive and negative rule sets, allow users to use rules that are less complex to develop and maintain. Rule sets are evaluated more efficiently by attempting to evaluate the rule set with less information than is needed to evaluate all the rules in the rule set. Also, the results of rules evaluations that are based on a set of values are cached for later retrieval.

Abstract: Described herein are various approaches that allow rules to be used to specify actions, that alleviate the complexity and burden of developing and maintaining rules in a rules-based messaging system, and that provide more efficient ways of evaluating rules. The approaches allow rules to specify user-defined transformation functions for transforming messages, to specify when and how to perform row migration, and to specify other types of actions. Rules are grouped into rule sets. Several types of rule sets, referred to as positive and negative rule sets, allow users to use rules that are less complex to develop and maintain. Rule sets are evaluated more efficiently by attempting to evaluate the rule set with less information than is needed to evaluate all the rules in the rule set. Also, the results of rules evaluations that are based on a set of values are cached for later retrieval.

Abstract: An extensible rules engine that uses database technology provides a rules evaluation service for applications external to the database server or database management system. Applications are able to utilize the rules engine to provide alternative behaviors based on information against which specified conditions are evaluated. A framework is provided for specifying data definitions that can be referenced by user-defined rules, through creation and use of an evaluation context. Application-specific data types can be defined by specifying data tables and/or variables that can be referenced by rules created for evaluation against data that is associated with the evaluation context. The data against which rules are evaluated can be provided as an in-memory object. A security model is provided in which the privilege to create rules according to a particular evaluation context is controlled by one privilege, whereas the privilege to access underlying tables or variables is controlled by another privilege.

Abstract: Communication costs are reduced in a distributed system that supports data replication with conflict detection by sending small values or nulls as replacements for field values that are not strictly used for replication or conflict detection. Specifically, nulls are propagated for new values of unmodified fields, old values of fields in unmodified groups of linked fields, and old values of fields for which conflict detection has been disabled. Flag values that indicate which actual old and new values were sent may be generated and propagated along with the replicated data.

Abstract: A method and apparatus for performing an administrative function on an object, replicated at a plurality of sites, suspends or "quiesces" replication activities at the granularity of an object group. Each object resides in an object group, and each object group has a status flag that indicates whether replication activities are quiesced. In response to detecting a request to perform an administrative function on an object, replication activities are suspended for the object group. Previous transactions are propagated to other sites. When each site has propagated all the previous transactions, the administrative function is performed and replication activities for the object group are resumed.

Abstract: A method and apparatus for replicating data among sites is provided. The method allows changes to the same body of data to be replicated synchronously to some destination sites and asynchronously to other destination sites. Such mixed propagation configurations allow synchronous updating to selected remote copies of replicated data where data integrity is a high priority, and asynchronous propagation to remaining copies of replicated data in order to allow transactions to be committed locally regardless of whether the transaction is committed at a remote copy of the replicated data. The propagation mode is selectable by a user on a site-to-site basis for each replicated body of data, thus providing a mix of availability and consistency that is not possible in purely synchronous or purely asynchronous replication systems.

Abstract: A method and system are provided for duplicating at a destination site changes made to data at a source site. According to the method a plurality of streams are established between the source site and the destination site. The plurality of streams are used in parallel to propagate changes made at the source site to the destination site. A record of transactions that made changes that need to be propagated from the source site to the destination site is maintained at the source site. Before propagating changes made by a transaction to the destination site on a stream of the plurality of streams, the record of transactions is inspected to identify a set of transactions whose changes are not known to have been made permanent at the destination site. It is then determined whether the transaction could possibly depend on any transaction in the set of transactions.