Abstract: Several embodiments of the present invention are directed to systems and methods for extending the UDT framework of an extended relational data store (ERDS) to include support for unordered collections (multisets) and ordered collection (lists). More specifically, several embodiments of the present invention use an UDT infrastructure, CLR generics, and a new UNNEST operator to create and utilize a special type abstraction for collections that is simultaneously a scalar and a relation. As a scalar, this collection type can be processed by all parts of the data store engine that understand scalars (including but not limited to the client stack) and, as a relation, this collection type is queriable like any other type of relation.

Abstract: A database system and method allows a user to write program code in a high-level programming language that implements a class that defines the structure of a user-defined type and methods that can be invoked on instances of the type. The class is then registered with the database system, which enforces a specific contract for user-defined types against the class. The contract comprises the following requirements. First, the class must specify one of a plurality of different formats for persisting instances of the user-defined type in a database store. Second, the class must be capable of returning a null value for the user-defined type. Third, the class must provide a method for converting the user-defined type to another type. Once these requirements are satisfied, the database system enables instances of the user-defined type to be created. A user-defined type can be used in all contexts where any other built-in type can be used.

Abstract: A new persistence format for storing objects of a user defined type in a database store enables information about the structure of the type to be communicated to the store. This information enables a number of store optimizations, including direct structural access to members of the type. Specifically, metadata is exchanged between the type implementer and the data store. The store uses the metadata to determine the storage layout for instances of the type. With this information, the store is able to detect access patterns that can be optimized to directly operate over the storage representation without hydration (deserialization) the object.

Abstract: A new persistence format for storing objects of a user defined type in a database store enables information about the structure of the type to be communicated to the store. This information enables a number of store optimizations, including direct structural access to members of the type. Specifically, metadata is exchanged between the type implementer and the data store. The store uses the metadata to determine the storage layout for instances of the type. With this information, the store is able to detect access patterns that can be optimized to directly operate over the storage representation without hydration (deserialization) the object.

Abstract: Efficient hierarchical searching is based on object type. By pre-computing additional information and storing it in a fast-lookup structure, it is possible to quickly identify objects that satisfy an object retrieval request. Furthermore, it is also possible to use this technique to avoid object hydration for operations in the store. Moreover, it is possible to leverage database statistical structures such as histograms to estimate the number of qualifying objects without having to examine each object.

Abstract: A system and method are provided for modeling structured, semi-structured, and unstructured data all within a single instance of a user defined type (UDT) within a database store. In particular, the XML data model is extended to fields of a UDT. As a result, the properties of the XML data model—such as document order and document structure—can be preserved within instances of a UDT. Moreover, code representing object behavior (i.e., methods that can be invoked on an object in managed code) can be added to the UDT to operate on an XML field, as well as non-XML fields of the UDT. This enables a framework for adding business logic to XML data. The content model of the XML data can be optionally described using XML schema documents associated with the XML fields of the UDT.

Abstract: Software and a method selectively apply a pessimistic concurrency control for each database update that conflicts with another database update. The method includes determining whether a database update conflicts with another database update, applying an optimistic concurrency control for each database update that does not conflict with another database update, and applying a pessimistic concurrency control for each database update that does conflict with another database update. This provides a selective locking concurrency control that selectively applies transaction serialization and locking only when transaction conflicts are detected. As a result, the selective locking concurrency control avoids livelock transaction failures and provides deterministic transaction completion without the computational expense of a conventional pessimistic concurrency control.

Abstract: Software and a method selectively apply a pessimistic concurrency control for each database update that conflicts with another database update. The method includes determining whether a database update conflicts with another database update, applying an optimistic concurrency control for each database update that does not conflict with another database update, and applying a pessimistic concurrency control for each database update that does conflict with another database update. This provides a selective locking concurrency control that selectively applies transaction serialization and locking only when transaction conflicts are detected. As a result, the selective locking concurrency control avoids livelock transaction failures and provides deterministic transaction completion without the computational expense of a conventional pessimistic concurrency control.

Abstract: A virtual machine computer includes multiple threads and can support multiple simultaneous workspaces. Within each workspace, multiple threads are able to access objects simultaneously. Threads are orthogonal to workspaces so that threads are not locked to particular workspaces, workspaces are not locked to particular threads, and the sizes of the workspaces are configurable to the requirements of the transactions within the workspaces. Such a virtual machine may be utilized in a variety of applications including transactional database applications in which multiple users have access to information (e.g., objects) in one or more shared databases. Such applications typically require that data transactions involving the objects in the shared database be performed reliably so as to maintain the integrity of the objects, which are sometimes called persistent objects.