Abstract: A request to execute a query is received in a database system. In response, the database system determines that a collection of data elements to be returned by the query corresponds to a first data structure not defined within a type dictionary of the database system. The database system obtains attribute values that describe respective data fields within the first data structure, and records, within the type dictionary, a first data type definition that specifies the data fields described by the attribute values.

Abstract: Techniques for managing XML data associated with multiple execution units ensure that execution units are able to use XML data coming from other execution units. Such techniques are applicable when, but for the technique, an XML type value is produced in a particular form by one execution unit and is supposed to be consumed by another execution unit that is unable to process data in the particular form, and involves detecting that the foregoing situation exists and annotating information sent to an XML producer execution unit to cause the XML type value to be transformed into a canonical form that can be shared by all relevant execution units.

Abstract: Techniques are described for executing queries that have XPath sections that specify unmappable paths. The techniques involve splitting the unmappable paths into (1) a mappable path fragment, and (2) an unmappable path fragment. After an unmappable path has been split into a mappable path fragment and an unmappable path fragment, the XPath section is replaced with a replacement XPath section. The replacement XPath section specifies two operations: a “mappable operation” that is based on the mappable path fragment, and an “unmappable operation” that is based on the unmappable path fragment. The portion of the replacement XPath section that specifies the mappable operation is rewritten to access underlying relational structures. Consequently, when the rewritten query is executed, a smaller amount of XML data needs to be materialized to evaluate the unmappable path fragment than would otherwise have been required to evaluate the original unmappable path.

Abstract: Disclosed is a method and mechanism for processing expressions and operator trees. An approach is particularly useful to optimize processing of XML statements with respect to SQL operators. A top-down processing approach can be taken to directly output data from operators to a data stream. In addition, multiple processing approaches can be taken within a single expression tree, with some operators processed using the top-down approach and other operators processed with the bottom-up approach. Even data that can not be streamed is copied fewer times using this approach, intermediate values from bottom-up processing may still be streamed if it is used by an operator that is eligible for top-down processing.

Abstract: A method, system and computer-readable medium is provided for grouping database objects into logical groupings in order to simplify administrative and other operations that need to be performed by the database server. Such operations can be performed once at the logical group level for a group of related objects, as opposed to at the individual database object level. For increased flexibility, the logical groupings need not dictate the format, schema or location of their members. A hierarchy may be established between the logical groupings, where child groupings inherit some or all of the properties of the parent groupings. A correspondence may be established between some groupings and operating system directories, allowing identifiers associated with the groupings to be used as aliases for the full operating system paths to the corresponding directories.

Abstract: A method and system for performing operations on large objects (LOBs) in a database system are provided. A server receives from a client a command that identifies a row of a table. The table includes a LOB column that contains LOBs. The server responds to the command by sending the client a first set of data from the row. The first set of data includes a locator for a LOB that belongs in the LOB column of the row. The locator includes a LOB identifier that uniquely identifies the LOB and snapshot information that identifies a particular version of the LOB. The server receives from the client a request to perform an operation on the LOB. The request passes the locator for the LOB to a routine provided by the server. The server performs the operation on the particular version of the LOB that is identified in the snapshot information contained in the locator passed to the server by the client.