Abstract: Queries that request fields that are contained in the same XML fragments are written to execute them more efficiently.

Abstract: A version history of each of a plurality of resources is stored in a table. The version history for each resource comprises a set of one or more values for the resource, wherein each value in the version history of a resource indicates the value that the resource had in a particular version of the resource. In response to a request to perform an operation that causes a given resource that is subject to a uniqueness constraint to have a particular value, it is determined whether the uniqueness constraint is violated based on whether any version of any resource other than the given resource has the particular value. The uniqueness constraint is determined to be violated if any version of any resource other than the given resource has the particular value. The uniqueness constraint is not violated by existence of a version of the given resource that has the particular value.

Abstract: A database server registers an XML schema and determines a database representation for the XML schema and mapping information, determining what database types should be used to represent an XML schema and/or how instances of the XML schema are stored by a database system. The mapping information indicates the mapping between the constructs declared in the XML schema and the constructs included in the appropriate database representation. The XML schema may contain annotations that describe one or more properties of a database representation of an XML date-time type. Based on the annotations, the database determines an appropriate database representation and generates mapping information mapping the declaration of the XML date-time type of the XML schema to the constructs of the database representation.

Abstract: To improve performance of performing XML operations on an XML document in by a client tier, the client generates an index that indexes the nodes of an XML document. The index may be generated, for example, by and during parsing of the XML document. The index contains similar structures to those maintained by a database server to perform XML operations on collections of XML documents. In lieu of parsing XML document to generate an index, the client may generate indexes based on data retrieved from the indexes at the database server.

Abstract: A “structural summary” of a collection of XML documents is generated. The structural summary is a skeleton tree that represents all parent-child relationships found in a XML document collection.

Abstract: Techniques are provided for accessing and storing files within a virtual folder. A virtual folder is a folder that is logically a part of a hierarchical folder structure of a file system repository, but the contents of the virtual folder are not physically stored in the file system repository. A client may issue, to an access mechanism, a request to perform a file operation on a file in a virtual folder. The access mechanism, which may be a database server or a component therein, may perform the file operation on the file in the virtual folder as if the file was stored in a particular folder within the hierarchical folder structure implemented by the file system repository. Advantageously, files may be physically stored outside of the file system repository, but still be a part of the hierarchical folder structure implemented by the file system repository.

Abstract: A method and apparatus for sharing state information among a plurality of servers is provided. A first server receives a request to perform a file operation, such as a NFS file system operation. Thereafter, the first server updates state information to reflect a change in state associated with processing the request. The first server then causes state update information, which identifies the change in state that was made at the first server, to be propagated to a second server. The second server updates state information, stored at the second server, to reflect the change in state associated with processing the request at the first server. Advantageously, a client may send a series of stateful file operations to either the first server or the second server, even if processing any one of the stateful file operation requests requires knowledge of the state of processing prior requests in the series of requests.

Abstract: A method and apparatus for performing network file system (NFS) operations across a plurality of servers is provided. At a first server, a filehandle for a particular file is generated based, at least in part, on an identifier that uniquely identifies the particular file relative to all other files within a file system repository. The file system repository may be implemented in a database. The identifier may also be stored in the database. The first server sends a client the filehandle. The client may thereafter send another request for the performance of a file operation, containing the filehandle, to a different server. The second server may read the filehandle and use the identifier to locate the file within the repository against which to perform the file operation without receiving, from the first server, information that associates the filehandle with the file.

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: A method and system are provided for allowing users to register XML schemas in a database system. The database system determines, based on a registered XML schema, how to store within the database system XML documents that conform to the XML schema. This determination involves mapping constructs defined in the XML schema to constructs supported by the database system. Such constructs may include datatypes, hierarchical relationship between elements, constraints, inheritances, etc. Once the mapping has been determined, it is stored and used by the database system to determine how to store subsequently received XML documents that conform to the registered XML schema.

Abstract: Techniques are provided for indexing XML documents using path subsetting. According to one embodiment, a PATH table created for storing one row for each indexed node of the XML documents using user-defined criteria. The user-defined criteria are used to determine which nodes of XML documents to included in The PATH TABLE. The PATH table row for a node includes (1) information for locating the XML document that contains the node, (2) information that identifies the path of the node, and (3) information that identifies the position of the node within the hierarchical structure of the XML document that contains the node. Use of the user defined criteria is transparent to any query improves DML indexes overhead costs.

Abstract: Described herein is a system for “lazy” manifestation of XML documents. In lazy manifestation, only portions of an XML document that contain data of interest (e.g., a particular element or attribute requested by an application) are manifested. The term “manifesting a portion of an XML document” refers to creating an in-memory representation of the portion and incorporating it into existing in-memory representation of an XML document, if any. These portions are referred to herein as a loadable unit. A loadable unit is a set of one or more nodes in an XML document, where when there is need to manifest a node in the set, other nodes in the loadable unit are manifested too. Loadable units may, but not necessarily, correlate to content structures that store the nodes. A loadable unit may be the nodes whose content is contained in a row.

Abstract: To associate XML data objects (“child objects”), stored in rows of relational or object-relational tables, with the appropriate XML data objects (“parent objects”) from which the child objects descend, tables that contain child objects (“out-of-line” tables) are constructed with an additional column. In one embodiment, this column stores values that identify the root objects, in the appropriate table, from which the respective child objects descend. Hence, the root object from which any given object descends is traceable by following the respective value back to the corresponding root object. In one embodiment, this column stores values that identify the complete XML hierarchical path, through multiple tables, back to the root object from which the respective child objects descend. Consequently, XML query language queries against XML documents stored in such tables can be rewritten as SQL queries against the data in the tables, even in the presence of cyclic constructs.

Abstract: Business logic is integrated within a repository through the use of “resource configurations.” A resource configuration is a unit of business logic that is supplied by a user to the repository and associated with a particular directory and/or a resource. Each resource configuration contains one or more configuration items that each defines and/or expresses one or more business rules for managing a resource associated with the resource configuration.

Abstract: A method and apparatus for performing file system operation locks at a database server is provided. A request to perform a file operation on a portion of a file managed by a database server is received at the database server. In response to receiving the request, the database server grants a lock that covers only a portion of the file that is involved in the file operation. For example, the database server may grant a lock that covers a range of bytes on the file, where the range of bytes is less than the entire file. Thereafter, the database server performs the file operation on the file. The file operation may be a NFS operation.

Abstract: A method and apparatus for reverting a resource to a prior state in time is provided. Changes are committed to a resource at a particular point in time. After the particular point in time, a request, which may be a file system operation request, to revert the resource to a state prior to the particular point in time is received at a database server. In response to the request, the resource is reverted to the state prior to the particular point in time. The current state of the resource ceases to reflect the plurality of changes. Advantageously, if a requestor creates an incorrect version of a resource, the changes made to a schema-based resource are not compatible with the schema, or the changes of multiple requesters are not compatible with each other, the resource may be reverted to the earlier point in time.

Abstract: A method and apparatus for providing file system operation locks at a database server is provided. A database server may employ database locks and file system operation locks in servicing requests from consistent requestors and inconsistent requesters. A database lock is a lock that is obtained in response to performing a database operation, and the database lock is released when the database operation has successfully completed. A file system operation lock is a lock that is obtained in response to performing an OPEN file system operation, and the file system operation lock is released when a CLOSE file system operation is performed. The database server may use a temporary copy of the resource, which reflects all the current changes that have been made to the resource by database operations, in servicing consistent requestors, and may use the original version of the resource in servicing inconsistent requesters.

Abstract: A method and apparatus for processing a file system operation at a database server is provided. A request to perform a file system operation on a resource stored in a database is received at a database system. The request may be implemented using the NFS protocol. The request may include state identification data that identifies state information associated with the request. State information associated with the request is retrieved within the database system based on the state identification data. State information is information that describes the operational state of the requestor for a particular file. The request is then processed based, at least in part, on the state identification. File system operations may be processed a database management system to access any data, such as a file, relational data, and object-relational data.

Abstract: A method and apparatus for performing an action in response to a file system event is provided. According to one aspect, sets of “event listeners” are associated with a file hierarchy and/or the nodes thereof. Each event listener contains a set of “event handlers.” Each event handler corresponds to a separate type of event that may occur relative to the file hierarchy's nodes. When an event is going to occur relative to the hierarchy or a node thereof, all event listeners that are associated with that hierarchy/node are inspected to determine whether those event listeners contain any event handlers that correspond to the event's type. Those event handlers that correspond to the event's type are placed in an ordered list of event handlers to be invoked. As the event handlers in the list are invoked, programmatic mechanisms that correspond to those event handlers are executed to perform customized user-specified actions.

Abstract: A method and apparatus for processing path-based database operations is provided. According to one aspect, a “parent row ID” column is added to a directory links table. For each row in the table, the value of the “parent row ID” column indicates the row ID, in the table, of the node that is that row's node's parent in the file hierarchy. To determine whether a particular node is within a specified path of the file hierarchy, the particular node's pathname is derived by visiting child-to-parent links indicated in the table and prepending, to the front of a pathname being constructed for the particular node, node names indicated in the visited rows. Each parent node's row in the directory links table is located using the “parent row ID” column of the child node's row. The resulting pathname is compared with the specified path to determine whether the particular node exists therein.