Abstract: A mechanism is provided for detecting and disregarding application specific nodes contained in shared XML documents. The techniques described involve determining one or more application specific nodes within XML documents and performing path expression evaluations of the XML documents as if the nodes are not present. In one embodiment, a mechanism is provided by which a user may specify the criterion that determine which subset of node in XML documents are to be ignored from path expression evaluations and evaluating a query that specifies a path operation based on a path and ignoring said identified nodes when evaluating said path operation.

Abstract: A platform (referred to herein as Extensible Application Platform, or XAP) for developing extensible business applications. In one set of embodiments, XAP can include an Extensible Markup Language (XML) based application model that is designed to support a high degree of application extensibility. For example, the XAP application model can support declarative definition of application semantics, separation of application data and metadata, and a flexible type system that allows constraints and calculations (e.g., XQuery constraints and calculations) for a data object instance (e.g., an XML document) to change over time. In certain embodiments, the XAP application model can be implemented via a server-side database/application engine that is configured to interoperate with a spreadsheet-like, client-side user interface. Using the spreadsheet-like UI, a non-programmer can build, customize, and run an application workflow that operates on top of a shared database like a traditional business application.

Abstract: A method for performing a neighbor-flipping transformation is provided. In one embodiment, a graph analysis program for computing a function relating to nodes in a directed graph is obtained and analyzed for neighborhood iterating operations, in which a function is computed over sets of nodes in the graph. For any detected neighborhood iterating operation, the method transforms the iterating operation by reversing the neighbor node relationship between the nodes in the operation. The transformed operation computes the same value for the function as the operation prior to transformation. The method alters the neighbor node relationship automatically, so that a user does not have to recode the graph analysis program. In some cases, the method includes construction of edges in the reverse direction while retaining the original edges in addition to performing the transformation.

Abstract: A method for generating a binary executable of a program so that private symbols in a module are accessible from another module. In one embodiment, the method compiles a source program to an intermediate representation and scans the representation to find the private symbols in the program's modules. It then wraps a function around each private symbol. When called, the function returns an address of the private symbol, so that the other module can access the symbol from outside the module in which the symbol is found. At run time, a call is made to obtain the address of the function, which is then executed to obtain the address of the private symbol so that the symbol can be accessed. In another embodiment, a Just-In-Time compiler executes the wrapper functions and patches the executable program with the direct address of the private symbol to avoid a call to the wrapper function.

Abstract: A system and method for allocating join processing between and RDBMS and an assisting cluster. In one embodiment, the method estimates a cost of performing the join completely in the RDBMS and the cost of performing the join with the assistance of a cluster coupled to the RDBMS. The cost of performing the join with the assistance of the cluster includes estimating a cost of a broadcast join or a partition join depending on the sizes of the tables. Additional costs are incurred when there is a blocking operation, which prevents the cluster from being able to process portions of the join. The RDBMS also maintains transactional consistency when the cluster performs some or all of the join processing.

Abstract: Techniques are provided for performing an invalidate operation in a non-coherent cache. In response to receiving an invalidate instruction, a cache unit only invalidates cache entries that are associated with invalidation data. In this way, a separate invalidate instruction is not required for each cache entry that is to be invalidated. Also, cache entries that are not to be invalidated remain unaffected by the invalidate operation. A cache entry may be associated with invalidation data if an address of the corresponding data item is in a particular set of addresses. The particular set of addresses may have been specified as a result of an invalidation instruction specified in code that is executing on a processor that is coupled to the cache.

Abstract: Techniques are provided for performing a flush operation in a non-coherent cache. In response to determining to perform a flush operation, a cache unit flushes certain data items. The flush operation may be performed in response to a lapse of a particular amount of time, such as a number of cycles, or an explicit flush instruction that does not indicate any cache entry or data item. The cache unit may store change data that indicates which entry stores a data item that has been modified but not yet been flushed. The change data may be used to identify the entries that need to be flushed. In one technique, a dirty cache entry that is associated with one or more relatively recent changes is not flushed during a flush operation.

Abstract: A method for performing a neighbor-flipping transformation is provided. In one embodiment, a graph analysis program for computing a function relating to nodes in a directed graph is obtained and analyzed for neighborhood iterating operations, in which a function is computed over sets of nodes in the graph. For any detected neighborhood iterating operation, the method transforms the iterating operation by reversing the neighbor node relationship between the nodes in the operation. The transformed operation computes the same value for the function as the operation prior to transformation. The method alters the neighbor node relationship automatically, so that a user does not have to recode the graph analysis program. In some cases, the method includes construction of edges in the reverse direction while retaining the original edges in addition to performing the transformation.

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 method for generating a binary executable of a program so that private symbols in a module are accessible from another module. In one embodiment, the method compiles a source program to an intermediate representation and scans the representation to find the private symbols in the program's modules. It then wraps a function around each private symbol. When called, the function returns an address of the private symbol, so that the other module can access the symbol from outside the module in which the symbol is found. At run time, a call is made to obtain the address of the function, which is then executed to obtain the address of the private symbol so that the symbol can be accessed. In another embodiment, a Just-In-Time compiler executes the wrapper functions and patches the executable program with the direct address of the private symbol to avoid a call to the wrapper function.

Abstract: A system and method for allocating join processing between and RDBMS and an assisting cluster. In one embodiment, the method estimates a cost of performing the join completely in the RDBMS and the cost of performing the join with the assistance of a cluster coupled to the RDBMS. The cost of performing the join with the assistance of the cluster includes estimating a cost of a broadcast join or a partition join depending on the sizes of the tables. Additional costs are incurred when there is a blocking operation, which prevents the cluster from being able to process portions of the join. The RDBMS also maintains transactional consistency when the cluster performs some or all of the join processing.

Abstract: Techniques are described for unifying static and dynamic compiler optimizations in source code bases. In an embodiment, a first compiler compiles source code of a target function to generate ahead-of-time (AOT) compiled machine code. A second compiler compiles the source code to generate an intermediate representation (IR) of the target function. In response to determining that the target function should be just-in-time (JIT) compiled, the AOT-compiled machine code for the target function is linked to the IR of the target function. During runtime, a physical processor executes AOT-compiled machine code of an executable program. When the target function is encountered for the first time, a JIT compiler is invoked. The JIT compiler generates JIT-compiled machine code for the target function. The physical processor executes the JIT-compiled machine code in place of the AOT-compiled machine code for the target function.

Abstract: A method for providing optimized data representation of relations for in-memory database query processing is disclosed. The method seeks to optimize the use of the available memory by encoding relations on which the in-memory database query processing is performed and by employing auxiliary structures to maintain performance. Relations are encoded based on data patterns in one or more attribute-columns of the relation and the encoding that is selected is suited to a particular type of data in the column. Members of a set of auxiliary structures are selected based on the benefit the structure can provide and the cost of the structure in terms of the amount of memory used. Encoding of the relations is performed in real-time while query processing occurs, using locks to eliminate conflicts between the query processing and encoding.

Abstract: A method and apparatus are described for sharing a session to access a database. A database server receives, in a session, a session context identifier and a command. The session context identifier identifies a session context to use for the session. The session context is a set of information or commands that plug into a session state and specify how commands in the session are to be performed for a particular user or privilege level. In response to receiving the identifier, the database server associates the session context with the database session for the connection. The database server uses the session context to process the command. The session context may then be detached from the session, allowing another user to attach to the session via another session context.

Abstract: A platform (referred to herein as Extensible Application Platform, or XAP) for developing extensible business applications. In one set of embodiments, XAP can include an Extensible Markup Language (XML) based application model that is designed to support a high degree of application extensibility. For example, the XAP application model can support declarative definition of application semantics, separation of application data and metadata, and a flexible type system that allows constraints and calculations (e.g., XQuery constraints and calculations) for a data object instance (e.g., an XML document) to change over time. In certain embodiments, the XAP application model can be implemented via a server-side database/application engine that is configured to interoperate with a spreadsheet-like, client-side user interface. Using the spreadsheet-like UI, a non-programmer can build, customize, and run an application workflow that operates on top of a shared database like a traditional business application.

Abstract: A mechanism is provided for detecting and disregarding application specific nodes contained in shared XML documents. The techniques described involve determining one or more application specific nodes within XML documents and performing path expression evaluations of the XML documents as if the nodes are not present. In one embodiment, a mechanism is provided by which a user may specify the criterion that determine which subset of node in XML documents are to be ignored from path expression evaluations and evaluating a query that specifies a path operation based on a path and ignoring said identified nodes when evaluating said path operation.

Abstract: A method and apparatus for efficiently maintaining XML index structures in a database system is provided. Instead of immediately synchronizing the XML index structures for every change submitted to the database, the changes are stored in a PENDING table. The XML index structures are periodically synchronized, based on certain criteria or at a user's discretion. Between synchronizations, the XML index structures may be in stale mode or current mode. If in stale mode, a request to access indexed information will use the XML index structures to find the desired indexed information without checking the PENDING table. If in current mode, a request to access indexed information will search the XML index structures and also check the PENDING table to determine 1) whether the indexed information has been updated or deleted, and 2) whether information relevant to the request has been inserted or updated.

Abstract: A database system automatically detects a cyclic construct in a XML schema, determines a database representation for the cyclic construct, and maps the XML schema and elements involved in the cyclic construct to the database representation.

Abstract: A method and apparatus are described for sharing a session to access a database. A database server receives, in a session, a session context identifier and a command. The session context identifier identifies a session context to use for the session. The session context is a set of information or commands that plug into a session state and specify how commands in the session are to be performed for a particular user or privilege level. In response to receiving the identifier, the database server associates the session context with the database session for the connection. The database server uses the session context to process the command. The session context may then be detached from the session, allowing another user to attach to the session via another session context.

Abstract: A mechanism is provided for detecting and disregarding application specific nodes contained in shared XML documents. The techniques described involve determining one or more application specific nodes within XML documents and performing path expression evaluations of the XML documents as if the nodes are not present. In one embodiment, a mechanism is provided by which a user may specify the criterion that determines which subset of nodes in XML documents are to be ignored from path expression evaluations. A query that specifies a path operation based on a path is evaluated ignoring said identified nodes when evaluating said path operation.