Abstract: Embodiments of the invention provide systems and methods for maintaining audit records for a database or other resource. According to one embodiment, a method for maintaining audit records for a database can comprise detecting an operation involving at least one record of the database. An audit record can be generated for the operation and the audit record can be stored in an audit table in the database. Insert operations and select operations for the audit table can be supported but other operations for the audit table can be prohibited. Additionally or alternatively, creation of more than one audit table having a same name and schema can be prevented.

Abstract: Techniques are provided for automatically tracking errors encountered by a software system. An occurrence of an error that affects performance of an operation being performed by a database server is detected. In response to detecting the occurrence, error information about the error is automatically recorded in a storage space within a database that is managed by the database server. The error information is automatically recorded by executing one or more computer instructions in a first code path of the database server, where the first code path is a separate code path than a second code path of the database server that performs the operation whose performance is affected by the error.

Abstract: Embodiments of the invention provide systems and methods for detection of tampering with an audit record for a database. According to one embodiment, a method for detection of tampering with an audit record for a database can comprise reading one or more audit records for a time period from an audit table. The one or more audit records can each include a time stamp and reading the one or more audit records can comprise reading audit records having a timestamp within the time period. An encrypted record, such as a message digest record, for the time period can be generated based on the one or more audit records and including the time stamps. The message digest record can be stored in a message digest table. In some cases, the message digest table can be maintained in a trusted data store.

Abstract: Techniques are provided for managing caches in a system with multiple caches that may contain different copies of the same data item. Specifically, techniques are provided for coordinating the write-to-disk operations performed on such data items to ensure that older versions of the data item are not written over newer versions, and to reduce the amount of processing required to recover after a failure. Various approaches are provided in which a master is used to coordinate with the multiple caches to cause a data item to be written to persistent storage. Techniques are also provided for managing checkpoints associated with the caches, where the checkpoints are used to determine the position at which to begin processing recovery logs in the event of a failure.

Abstract: One embodiment of the present invention provides a system for executing a command on a computer system. During operation, the system receives a signed command from a first quorum member at a security manager, wherein one or more quorum members must accept the command before the command is executed. Along with the command is data indicating which additional quorum members will be participating in a session, and which quorum persona they wish to invoke for the session. After verifying the signature, the system sends the command to a second quorum member, wherein the command is verified, or authenticated as originating from the first quorum member. Next, the system receives a signed response from the second quorum member, wherein the response indicates whether the second quorum member accepts or rejects the command. If the second quorum member accepts the command, the system sends the command to a native client which executes the command.

Abstract: Techniques are provided for automatically diagnosing errors in a software system. The software system automatically determines whether conditions associated with the software system warrant use of any diagnostic features that are not currently enabled. When the software system determines that the conditions associated with the software system warrant use of any diagnostic features that are not currently enabled, the software system determines which of a plurality of available diagnostic features should be enabled. The software system then enables the determined one or more diagnostics features.

Abstract: Techniques for performing window-by-window remastering are described, in which the mechanism used by nodes to determine the resource-to-window mapping is separated from the mechanism used by the nodes to access resource information. For example, all nodes of a multiple-node system may use the same hash function to determine which resources are involved in a remastering window. However, the resource indexes employed by the nodes to access resource information need not use that same hash function. For example, in nodes where the resource indexes are hash indexes, different nodes may use different hash functions. Further, some or all of the nodes may use mechanisms other than hash indexes to access the resource information.

Abstract: Systems and methods for managing the processing of the same pieces of information, e.g., messages, by multiple consumers, in a prescribed order, without causing the degradation of any consumer's performance because of other consumers' access to the same information. A single information queue contains pieces of information to be accessed by multiple consumers. Each piece of information is stored in the information queue along with an information identifier that uniquely identifies the piece of information. A separate table is used to keep track of and identify the pieces of information in the information queue that have been accessed by respective consumers. This separate table is decoupled from the information queue, and, thus, each consumer's access of a piece of queued information does not impact any other consumer's access of the same piece of information.

Abstract: Techniques are provided for managing caches in a system with multiple caches that may contain different copies of the same data item. Specifically, techniques are provided for coordinating the write-to-disk operations performed on such data items to ensure that older versions of the data item are not written over newer versions, and to reduce the amount of processing required to recover after a failure. Various approaches are provided in which a master is used to coordinate with the multiple caches to cause a data item to be written to persistent storage. Techniques are also provided for managing checkpoints associated with the caches, where the checkpoints are used to determine the position at which to begin processing recovery logs in the event of a failure.

Abstract: Techniques are provided for evaluating base events, compound events, and logical update events in an event processing system. In one embodiment, the base events, compound events, and logical update events are definitions in a particular syntax language that specify conditions for evaluating input event data. In this embodiment, base event definitions are evaluated over the input event data; logical update event definitions are evaluated by determining whether the effect of any earlier event is changed by the arrival of a new event; and compound event definitions are evaluated over records representing events that have been selected by evaluating the base event definitions over the input event data.

Abstract: A system and method for estimating data conflicts in a multi-node system is disclosed. According to an embodiment of the invention, tracing the execution of a workload on a single node and analyzing the trace records makes it possible to predict how many data conflicts would occur if the workload were executed across multiple nodes. Also disclosed is a method and mechanism for generating a load distribution plan for a multi-node system.

Abstract: Techniques are described for storing portions of files on different storage devices based on the devices' respective storage class. For example, different extents from a large file within a system, application, or database may be stored on different storage devices. The storage devices may be part of a single storage system that includes some storage devices that have different performance capabilities. The decision of where, within the storage classes, to store data may be based on the access patterns of the data. Access patterns regarding file extents are tracked using respective access bits, which are set when a memory block associated with an extent is accessed via an I/O operation. In one embodiment, an access bitmap is modified to account for cached blocks of file extents.

Abstract: A system is provided to prevent unauthorized access to computer system resources. The system operates by receiving a section of programming language code to execute on a computer system. This programming language code includes a pragma that defines a set of resources that the programming language code has permission to access. The system analyzes the pragma to determine the set of resources. After analyzing the pragma, the system processes the programming language code in accordance with the pragma. The system can further process the program in accordance with the pragma involves creating a sandbox that includes the set of resources defined by the pragma. The system then executes the programming language code within the boundaries of the sandbox.

Abstract: The disclosed techniques for event notification enable applications that rely on event notifications to be ported transparently to clustered computing systems. The disclosed techniques for event notification exploit the characteristics of a clustered computing system and the characteristics of event notification in order to provide efficient event notification in clustered computing environments.

Abstract: Techniques are provided for managing caches in a system with multiple caches that may contain different copies of the same data item. Specifically, techniques are provided for coordinating the write-to-disk operations performed on such data items to ensure that older versions of the data item are not written over newer versions, and to reduce the amount of processing required to recover after a failure. Various approaches are provided in which a master is used to coordinate with the multiple caches to cause a data item to be written to persistent storage. Techniques are also provided for managing checkpoints associated with the caches, where the checkpoints are used to determine the position at which to begin processing recovery logs in the event of a failure.

Abstract: Embodiments of the invention provide systems and methods for maintaining audit records for a database or other resource. According to one embodiment, a method for maintaining audit records for a database can comprise detecting an operation involving at least one record of the database. An audit record can be generated for the operation and the audit record can be stored in an audit table in the database. Insert operations and select operations for the audit table can be supported but other operations for the audit table can be prohibited. Additionally or alternatively, creation of more than one audit table having a same name and schema can be prevented.

Abstract: Embodiments of the invention provide systems and methods for detection of tampering with an audit record for a database. According to one embodiment, a method for detection of tampering with an audit record for a database can comprise reading one or more audit records for a time period from an audit table. The one or more audit records can each include a time stamp and reading the one or more audit records can comprise reading audit records having a timestamp within the time period. An encrypted record, such as a message digest record, for the time period can be generated based on the one or more audit records and including the time stamps. The message digest record can be stored in a message digest table. In some cases, the message digest table can be maintained in a trusted data store.

Abstract: A method and apparatus for determining when an event occurred in a database is provided. At least a portion of the database is restored to a point in time that is prior to the event. Recovery logs are translated to database operations (e.g., SQL) that are capable of causing the changes described in the recovery logs. A mechanism is created for detecting the event based on execution of the statements. For example, a database trigger is created to detect the event. The database operations are executed against the restored database to cause the mechanism to detect the event.

Abstract: A lock manager system is provided that includes multiple distinct mechanisms for assigning resources to masters. Specifically, the lock manager system includes (1) one or more assignment mechanisms that do not take into account the affinity between nodes and objects (“affinity-independent assignment mechanisms”), and (3) one or more assignment mechanisms that do take into account the affinity between nodes and objects (“affinity-based assignment mechanisms”). At any given time, the assignment of any given resource to a master is governed by only one of the multiple assignment mechanisms employed by the system. Various techniques are described for determining which assignment mechanism to use with which resources.

Abstract: Techniques are provided for automatically tracking errors encountered by a software system. An occurrence of an error that affects performance of an operation being performed by a database server is detected. In response to detecting the occurrence, error information about the error is automatically recorded in a storage space within a database that is managed by the database server. The error information is automatically recorded by executing one or more computer instructions in a first code path of the database server, where the first code path is a separate code path than a second code path of the database server that performs the operation whose performance is affected by the error.