Abstract: A method and apparatus for managing data in a partitioned data storage space is provided. Data referencing a new data item to be stored in the data storage space is received. It is determined that the data item does not pertain to any previously created partition. In response to the determination, a new partition is automatically created in the data storage space. The partition is mapped to a new set of values, such as to a next unpartitioned interval of dates or numbers.

Abstract: An XML join between XML documents can be performed by comparing XML elements between the XML documents, obtaining join-selection elements from a first XML document, obtaining join-required elements from one or more other XML documents, and performing the XML join using the elements in the first XML document and the join-required elements. The XML documents can be at different locations connected via a network. Where two XML documents are at different locations, the join-selection elements can be transmitted from a first location (of a first XML document) to a second location (of a second XML document). The join-required elements can be obtained at the second location and transmitted back to the first location. The XML join can then be performed at the first location.

Abstract: Processing a multiple table query includes: determining if any tables in the query require materialization; for each table in the query that requires materialization, deriving at least one join predicate on a join column; determining if any tables earlier in a join sequence for the query has same join predicates; and applying the at least one derived join predicate to an earlier table in the join sequence, if there is at least one table earlier in the join sequence that has the same join predicate. This significantly reduces the number of rows that are joined before arriving at the final result.

Abstract: A partition management system is disclosed for a database comprising at least one database table. The system comprises a partition controller arranged to automatically create at least one table partition in advance so that at least one table partition is available prior to when the table partition is required by the database. A corresponding method is also disclosed.

Abstract: A method of preparing customised reports from source data comprises: retrieving a report definition from a first database; loading the retrieved report definition into a report-generating means, wherein the report-generating means is independent of said first database; retrieving source data from a second database into said report-generating means as specified by said report definition; and performing operations on said retrieved source data to produce a report in accordance with the report definition.

Abstract: A method is provided for managing, in a computer system, design of a database system having a set of schemata. The method includes, in a first computer process, extracting dependencies from the database system and identifying the set of schemata. The method further includes, for each specific schema in the set of schemata, creating in a second computer process a partition that, in turn, contains a further partition for each element of the specific schema, so as to establish a hierarchy of partitions in accordance with the structure of the set of schemata. The method also includes storing a representation of the database system including subsystems, dependency relationships among the subsystems, and the hierarchy of partitions.

Abstract: Techniques for left outer join (LOJ) and right outer join (ROJ) optimization are described herein. Each LOJ/ROJ is an expression that references a preserved side and a null supplying side. If Condition 1 is true, and either Condition 2 or Condition 3 is true, then the LOJ/ROJ is evaluated by evaluating the expression referencing only the preserved side, and not the null supplying side. Conditions 1, 2 and 3 are defined as follows: Condition 1: An expression from the null supplying side is not used outside of the LOJ/ROJ. Condition 2: The LOJ/ROJ is required to return only distinct values from the preserved side. Condition 3: The null supplying side returns at most one row for each row returned by the preserved side.

Abstract: A database engine and a system running a database engine utilize a dynamic join reordering feature to change the order of two or more join operations while a query is executing. The database engine starts execution of the query with an initial join order setting but monitors the execution of the query to determine whether the initial join order or some other join order would provide better runtime performance. If another join order would provide better performance, then the database engine can change the join order during query execution and complete the query using the new join order.