Abstract: In accordance with an embodiment, described herein is a system and method for connection concentration in a database environment. A transparency engine provided between client applications and a database can include a connection pool (e.g., UCP connection pool). The transparency engine can operate as a proxy engine for the database and as a session abstraction layer for the client applications, to enable the client applications to utilize features provided by the connection pool without code changes. The transparency engine can receive application connections from the client applications, and concentrate the application connections on a smaller number of database connections maintained in the connection pool.

Abstract: In accordance with an embodiment, described herein is a system and method for connection concentration in a database environment. A transparency engine provided between client applications and a database can include a connection pool (e.g., UCP connection pool). The transparency engine can operate as a proxy engine for the database and as a session abstraction layer for the client applications, to enable the client applications to utilize features provided by the connection pool without code changes. The transparency engine can receive application connections from the client applications, and concentrate the application connections on a smaller number of database connections maintained in the connection pool.

Abstract: In accordance with an embodiment, described herein is a system and method for high availability and load balancing in a database environment. A transparency engine can be provided between client applications and a database, and can operate as a proxy engine for the database and as a session abstraction layer for the client applications, to enable the client applications to utilize database features provided by the connection pool without code changes to the client applications. The transparency can keep track of session states, request boundaries and cursors to efficiently reuse the database connections across the client applications. The transparency engine can use the request boundaries and indicators from the database to detect safe places to drain database connections in the event of database outages.

Abstract: In accordance with an embodiment, described herein is a system and method for high availability and load balancing in a database environment. A transparency engine can be provided between client applications and a database, and can operate as a proxy engine for the database and as a session abstraction layer for the client applications, to enable the client applications to utilize database features provided by the connection pool without code changes to the client applications. The transparency can keep track of session states, request boundaries and cursors to efficiently reuse the database connections across the client applications. The transparency engine can use the request boundaries and indicators from the database to detect safe places to drain database connections in the event of database outages.

Abstract: Techniques are described for providing a guaranteed commit outcome for global transactions that are optimized by deferring the commit processing to a resource manager, such as a DBMS, using optimizations. The “Distributed Transaction Processing: The XA Specification” standard specification is ambiguous regarding commit outcomes for transactions managed by DBMS, resulting in wrong results for vendors implementing the standard. The techniques described provide a guaranteed commit outcome when using the optimizations, creating the opportunity for safe replay of global transactions when a communication error or timeout occurs between the transaction manager and the resource manager, and eliminating ambiguous transaction outcomes reaching applications and end users. Techniques described herein distinguished between global transactions in a session managed by a transaction manager, and those in the same session that are managed by the resource manager using the optimizations.

Abstract: A system and method for reducing communications overhead in a distributed transaction processing environment such as an XA environment. In accordance with an embodiment communication overhead is reduced in a transaction by deferring a transaction end communication. The deferred transaction end communication is determined from a subsequent XA transaction communication thereby reducing the number of networks calls required for each transaction and enhancing system performance.

Abstract: In accordance with an embodiment, described herein is a system and method for connection concentration in a database environment. A transparency engine provided between client applications and a database can include a connection pool (e.g., UCP connection pool). The transparency engine can operate as a proxy engine for the database and as a session abstraction layer for the client applications, to enable the client applications to utilize features provided by the connection pool without code changes. The transparency engine can receive application connections from the client applications, and concentrate the application connections on a smaller number of database connections maintained in the connection pool.

Abstract: In accordance with an embodiment, described herein is a system and method for high availability and load balancing in a database environment. A transparency engine can be provided between client applications and a database, and can operate as a proxy engine for the database and as a session abstraction layer for the client applications, to enable the client applications to utilize database features provided by the connection pool without code changes to the client applications. The transparency can keep track of session states, request boundaries and cursors to efficiently reuse the database connections across the client applications. The transparency engine can use the request boundaries and indicators from the database to detect safe places to drain database connections in the event of database outages.

Abstract: A system and method for reducing communications overhead in a distributed transaction processing environment such as an XA environment. In accordance with an embodiment communication overhead is reduced in a transaction start method by deferring a transaction start communication. The deferred transaction start communication is determined from a subsequent transaction processing communication thereby reducing the number of networks calls required for each transaction and enhancing system performance.

Abstract: Techniques are described for providing a guaranteed commit outcome for global transactions that are optimized by deferring the commit processing to a resource manager, such as a DBMS, using optimizations. The “Distributed Transaction Processing: The XA Specification” standard specification is ambiguous regarding commit outcomes for transactions managed by DBMS, resulting in wrong results for vendors implementing the standard. The techniques described provide a guaranteed commit outcome when using the optimizations, creating the opportunity for safe replay of global transactions when a communication error or timeout occurs between the transaction manager and the resource manager, and eliminating ambiguous transaction outcomes reaching applications and end users. Techniques described herein distinguished between global transactions in a session managed by a transaction manager, and those in the same session that are managed by the resource manager using the optimizations.

Abstract: A system and method for reducing communications overhead in a distributed transaction processing environment such as an XA environment. In accordance with an embodiment communication overhead is reduced in a transaction by deferring a transaction end communication. The deferred transaction end communication is determined from a subsequent XA transaction communication thereby reducing the number of networks calls required for each transaction and enhancing system performance.

Abstract: A system and method for reducing communications overhead in a distributed transaction processing environment such as an XA environment. In accordance with an embodiment communication overhead is reduced in a transaction start method by deferring a transaction start communication. The deferred transaction start communication is determined from a subsequent transaction processing communication thereby reducing the number of networks calls required for each transaction and enhancing system performance.

Abstract: Techniques for routing client requests among a group of nodes offering a service are described. A coordinator determines that performance could be improved by using affinity-based routing. In one embodiment, the coordinator calculates a Time-to-Live (TTL) metric whereby clients benefit by returning to the same cache and posts this hint to subscribers. Client's start preserving locality data in an affinity context, such that later requests for a connection can be routed to the location last visited. The coordinator measures the system over subsequent intervals. If the gradient of the goodness (viz service quality and capacity) is stable or improving, then the coordinator continues to advise subscribers to use the affinity-based technique. Alternatively, if the gradient of the goodness is deteriorating, then the coordinator posts advice to the subscribers to stop using the affinity-based technique for any instance during the next intervals.

Abstract: A method and apparatus is provided for automatically performing an operation for one or more resources of a computing cluster when a conditional dependency is satisfied. The conditional dependency may be based on the operating state, load, performance metric, or performance statistic of one or more other resources. A resource profile for a resource stores a conditional dependency that, when satisfied, causes a centralized policy engine to send a command to the resource or an agent for the resource. The policy engine receives notifications of operating state changes from agents that manage resources in the cluster. The policy engine determines that one or more conditional dependencies is satisfied when one or more resources change state to satisfy conditions specified by the conditional dependencies. The policy engine responds to detecting that a conditional dependency is satisfied by sending a command that causes the dependent resource to change its operating state.

Abstract: Techniques for fast recovery and/or balancing of connections to a clustered computing system provide management of such connections by determining a number of connections to load balance across nodes and by triggering creation of such connections. In one aspect, a notification of an event regarding the clustered computing system is received by a connection pool manager, a pool of connections to the system is identified based on the notification, and one or more connections from the pool are processed in response to the event. According to an embodiment, the notification comprises the identities of the service, database, server instance and machine that correspond to the event.

Abstract: A method and apparatus for selecting one or more instances to perform database recovery is provided. According to one aspect, one or more performance metrics are determined for each instance on each node in a cluster. Based on these performance metrics, which may be weighted to give one or more metrics more significance relative to the other metrics, an overall score is determined for each instance on each surviving node when a node in the cluster fails. One or more instances with the highest of these scores are selected. The selected instances are assigned the task of performing the database recovery process. Because instances best able to handle to database recovery process are selected, the database recovery process consumes less time, thereby making data accessible in less time after a node fails.

Abstract: With fast notification of changes to a clustered computing system, through which a number of events are published for system state changes, applications can quickly recover and sessions can quickly be rebalanced. When a resource associated with a service experiences a change in status, such as a termination or a start/restart, a notification event is immediately published. Notification events contain information to enable subscribers to identify, based on matching a session signature, the particular sessions that are affected by the change in status, and to respond accordingly. This allows sessions to be quickly aborted and ongoing processing to be quickly terminated when a resource fails, and allows fast rebalancing of work when a resource is restarted.

Abstract: Approaches for manage and measuring workload on computer resources by measuring workload in ways that are independent of physical hardware and that correlate to ways in which it is desirable to measure and manage workload for applications and clients. Specifically, logical abstractions of workload, referred to as services, are defined for a cluster of nodes running a multi-node database server of a database. A service is a category of work hosted on a subset of multi-node database servers, such as work that is performed for an online order entry application. The workload is measured and demarcated by the service no matter which node in a single or multi-node system performs the service, providing a global view of performance realized by the system.

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: Techniques for routing client requests among a group of nodes offering a service are described. A coordinator determines that performance could be improved by using affinity-based routing. In one embodiment, the coordinator calculates a Time-to-Live (TTL) metric whereby clients benefit by returning to the same cache and posts this hint to subscribers. Client's start preserving locality data in an affinity context, such that later requests for a connection can be routed to the location last visited. The coordinator measures the system over subsequent intervals. If the gradient of the goodness (viz service quality and capacity) is stable or improving, then the coordinator continues to advise subscribers to use the affinity-based technique. Alternatively, if the gradient of the goodness is deteriorating, then the coordinator posts advice to the subscribers to stop using the affinity-based technique for any instance during the next intervals.