Abstract: A method for combining within memory a limit, a plurality of bitmap streams from bitmaps of indefinite size and number. The bitmap streams are merged into a resulting bitmap which can be used in subsequent logical operations.In order to perform a merge within a memory limit, the method relies on the data compression. When compression by itself may be ineffective, the method produces a resulting bitmap for a reduced range.The ensures the production of a resulting bitmap. When the range is reduced, the method may be repeated to produce a merge for a range beyond the reduced range.

Abstract: In processing a query, a database server parses a string describing a query into a query representation. The query string is parsed again to generate a replica of the query representation. Various transformations can be applied to the replica in order to reduce the amount of processing for the query. In addition, transformations are applied to the query string before parsing again to produce a transformed query representation. A transformed query representation is selected for processing a query according to an estimated cost of using the query representation.

Abstract: A method and apparatus for reducing the number of snapshots in use within a database is provided. A transaction that accesses one or more data items in a database is assigned to a snapshot of the database when the transaction completes execution. At that time, it is determined whether a first snapshot includes any transactions that updated the one or more data items. If the first snapshot includes any transactions that updated the one or more data items, then the transaction is assigned to a different snapshot that includes the first snapshot. If the first snapshot does not include any transactions that updated the one or more data items, then the transaction is assigned to the first snapshot. This technique allows multiple transactions to the same snapshot, consequently reducing the actual number of snapshots of the database.

Abstract: A method and apparatus for supplying data from a database to a group of transactions is provided. A value is maintained for the group of transactions. The value indicates a target snapshot of the database. When a transaction within the group of transactions accesses a data item, it is determined whether the transaction can use the target snapshot. If the transaction can use the target snapshot, then the transaction is supplied a version of the data item that belongs to the target snapshot. If the transaction cannot use the target snapshot, then the transaction is supplied a version of the data item other than the version of the data item that belongs to the target snapshot. Trying to supply data from the same snapshot to all of the transactions in the group increases the likelihood that the transactions will be able to use the same version of any given data item.

Abstract: A method and apparatus for parallelizing operations that change a database is provided. A coordinator process receives a statement that requires data to be written into the database. In response to the statement, the coordinator process assigns granules of work to multiple processes. Each of the multiple processes executes the granule of work by writing to the database a distinct portion of the set of data that is to be added to the database. The various portions of data are then merged to update the set of data to be added to the database.

Abstract: A method and apparatus for inserting sorted data into an indexed table is provided. Two or more nodes are used to insert the data into the indexed table. Before an entry for each inserted row is stored in the index associated with the table, the key values in the index entry are transformed using an operation that affects the order of the key values. For example, the order of the bytes used to represent the key values in the index entry may be reversed. The index entries are stored in the portion of the index that corresponds to the transformed key values. As a result, the entries for consecutive key values will not necessarily be stored in the same portion of the index. Consequently, the nodes will not have to compete for a "hot" portion of an index if the nodes are inserting data with key values that fall into the same approximate range. The inverse of the transformation operation is performed on the transformed key values read from the index before the key values are supplied to the user.

Abstract: A research mode in a search and retrieval system generates a research document that infers an answer to a query from multiple documents. The search and retrieval system includes point of view gists for documents to provide a synopsis for a corresponding document with a slant toward a topic. To generate a research document, the search and retrieval system processes a query to identify one or more topics related to the query, selects document themes relevant to the query, and then selects point of view gists, based on the document themes, that have a slant towards the topics related to the query. A knowledge base, which includes categories arranged hierarchically, is configured as a directed graph to links those categories having a lexical, semantic or usage association. Through use of the knowledge base, an expanded set of query terms are generated, and research documents are compiled that include point of view gists relevant to the expanded set of query terms.

Abstract: A linked list of items in a sorted order is created and stored in memory. In addition to the linked list of items, an auxiliary array is also created and stored in memory. The auxiliary array contains pointers to a subset of items from the linked list. When a request is received to locate a particular item in the linked list, a binary search is first performed on the pointers stored in the auxiliary array. The result of this search provides a pointer for accessing an entry-point item on the linked list. The entry-point item is either the particular item or is an item that precedes the particular item in the linked list. The linked list is then traversed from the entry-point item rather than from a starting pointer (i.e., head) until the particular item is accessed.

Abstract: In a relational database management system (RDBMS), a method of issuing input/output tasks (I/Os) which store record information from a buffer to an after image journal (AIJ) file of a durable disk (the AIJ device) where a group commit size is dynamically adapted to the workload of the AIJ device and to the character and volume of data written to the AIJ file. Record information contains data records (including roll back records) and/or commit records that together form database transactions. A commit record written to the AIJ file indicates that data modifications and/or additions embodied in data records associated with the commit record are durable in the RDBMS in that they are stored in a durable media and are recoverable.

Abstract: A method and system periodically copies information from a computer file to a database to preserve non-current information from the file. As information from the file is overwritten by new information, the old information is preserved in the database, allowing non-current information to be used without reprogramming the computer programs or portions of the computer program that read or write the file. If the file is arranged into one or more sections, and new information stored in a section of the file is assigned an identifier higher than the other information in the section, the amount of time required to locate new information in the file can be reduced. Comparing the highest identifier in the section with the highest identifier in the database for that section can identify sections of the file that have received no new information since the last update made to the database.

Abstract: In a multi-threaded computing system, a locking system is utilized to cooperatively manage a shared cache between a plurality of user threads and a paging manager thread. To manage the locks, the paging manager maintains pointers between a process memory space assigned to each user thread, a global system data structure assigned to each user thread, and a page control block for each locked page in memory. These pointers and additional flags identify locked pages and their owners, and facilitates cleanup of stale locks.

Abstract: A method for providing security and password mechanisms in a data base system. The method limits access to the database to clients who transmit a valid password and user ID combination. Furthermore, the method requires that passwords are changed periodically. The method ensures that passwords meet certain criteria. Finally, the method provides a script which can be used to extend the security and password mechanisms.

Abstract: In a multi-dimensional database, a composite data construct is created to accommodate sparse dimensions. When the database is defined, sparse dimensions are identified and composites of those sparse dimensions are created. The composites are stored in a linearized array. The amount of storage space allocated is chosen by the database administrator to satisfy reasonable expected growth of the sparse data.

Abstract: A knowledge base search and retrieval system, which includes factual knowledge base queries and concept knowledge base queries, is disclosed. A knowledge base stores associations among terminology/categories that have a lexical, semantical or usage association. Document theme vectors identify the content of documents through themes as well as through classification of the documents in categories that reflects what the documents are primarily about. The factual knowledge base queries identify, in response to an input query, documents relevant to the input query through expansion of the query terms as well as through expansion of themes. The concept knowledge base query does not identify specific documents in response to a query, but specifies terminology that identifies the potential existence of documents in a particular area.

Abstract: A method and apparatus for replicating data among sites is provided. The method allows changes to the same body of data to be replicated synchronously to some destination sites and asynchronously to other destination sites. Such mixed propagation configurations allow synchronous updating to selected remote copies of replicated data where data integrity is a high priority, and asynchronous propagation to remaining copies of replicated data in order to allow transactions to be committed locally regardless of whether the transaction is committed at a remote copy of the replicated data. The propagation mode is selectable by a user on a site-to-site basis for each replicated body of data, thus providing a mix of availability and consistency that is not possible in purely synchronous or purely asynchronous replication systems.

Abstract: A relational mapper supports the storage of objects from an object oriented environment in one or more relational databases. The relational mapper generates tables in a relational data store for abstract class types, and it generates a mapping, in any predetermined relationship, to map at least one member of an object to a table for the class type in the relational data store. The relational mapper maps members of a class type to members of a data source. A storage type map is generated to map the data source members of the data source to columns of the relational database table for the class type. The relational mapper is bidirectional such that the relational mapper maps data from a relational database to create objects in accordance with a type system of an object oriented environment. The relational mapper generates metadata to describe the object such that the object, created from the relational database, is a full fledged object of the object oriented system.

Abstract: A record management system is provided for generating a multi-dimensional view for different measures. A set of records is retrieved in response to a set of queries. The records include dimension values and measure values, which are associated with the measures. The set of records is maintained in a master table. The record management system generates a record structure foundation, including a query map and a master table index. The record management system then employs the record structure foundation to generate a multi-dimensional layout mapping for the measures that are to be represented in the view. The record structure foundation and measure values in the master table are used to convert the layout mapping into the desired multi-dimensional view. The record management system includes data storage units for implementing the master table, query map, master table index, and layout mapping.

Abstract: In a client/server computer system, a method for writing modified data in a cache memory back to a database residing in a hard disk drive. Rather than writing back all of the modified data as part of a checkpointing operation, the present invention designates an amount of the cache memory that is to be cleared for a pre-determined time interval. The amount of cache memory to be cleared is based on an estimate of how much new data is anticipated to be cached. Thereby, just enough memory is cleared and made available so as to accommodate the storage of new data. For the modified data which are to be written back to the database, a lazy writeback operation is utilized.

Abstract: A software system having a software application that generates an event notification message for each of a set of predefined significant events and having a custom extension module that receives the notification message and then selects a coordination style. The coordination style determines whether a custom event handler for the significant event contained in the custom extension module supplements or replaces a default event handler for the significant event contained in the software application.

Abstract: A document classification system includes disambiguation processing to validate categories that have been preliminarily classified for themes of a document. The themes of a document are preliminarily classified through use of a classification hierarchy that contains a plurality of categories. The disambiguation processing determines, for a theme selected for disambiguation, whether the category preliminarily classified for the theme selected is valid by analyzing the relationships among the category preliminarily classified for the theme and other categories classified for different themes in the document. The disambiguation processing also utilizes a category cross reference database, which comprises a list of category cross reference pairs, to disambiguate categories assigned to themes by pairing a category classified for a theme and other categories classified for other themes in the document and by comparing these category pairs with category cross reference database pairs.