Abstract: A method and apparatus allows clients to share ports on a server. The server can maintain more sessions than server ports. When a client sends a command directed to the server, a resource manager inserted between the clients and the server intercepts the command and directs the server to select the session associated with a client prior to or at the same time that the resource manager forwards the intercepted command to the server. Responses from the server are forwarded by the resource manager to the client that sent the command to which the response relates. The resource manager may be coupled to multiple clients, and one or more ports of one or more servers.

Abstract: A method and apparatus for generating and using bitmaps in a database system that employs multi-level identifiers is provided. The generated bitmaps include bits that correspond to the identifiers that have been assigned to existing records, as well as bits that correspond to all intervening multi-level identifiers that have not yet been assigned. Therefore, when new rows are inserted into the table associated with the bitmap, new bits do not have to be inserted into the existing bitmap. When existing rows are deleted, the bits that correspond to the deleted rows are not themselves deleted, but are simply set to a value that indicates that the corresponding row does not satisfy the criteria associated with the bitmap.

Abstract: In a multi-threaded computing environment, a shared cache system reduces the amount of redundant information stored in memory. A cache memory area provides both global readable data and private writable data to processing threads. A collection mechanism monitors the amount of cache memory available to the processing threads. In particular, a collector thread is executed when needed to reclaim least recently used cache memory.

Abstract: Techniques for determining a safe recovery time value after a failure of a first node in a computer system are described. According to the techniques, every node in a multi-node parallel database system maintains a logical clock for generating timestamps. The logical clocks are synchronized by attaching a current timestamp to every message that is sent by a node. When a node receives an incoming timestamp that is greater than the value indicated by the associated logical clock, it sets the associated logical clock forward to at least the value of the timestamp. When a node fails, a recovery node calculates a "safe" logical clock value to use in recovering the crashed node. In calculating the "safe" logical clock value, the recovery node searches specific areas of the database to locate and recover a most recent timestamp value associated with the crashed node.

Abstract: A method and system for executing an application at a client are described. An application is divided into portions. A first portion of code for the application is transmitted to the client over a network. The first portion of code is executed at the client to cause the client to generate a user interface that is displayed by the client, detect user interaction with the user interface, and transmit from the client over the network messages that indicate the user interaction with the user interface. A second portion of code for the application is executed at a node of the network other than the client. The second portion of code causes the node on which it is executing to respond to user interface messages from the client by (1) generating records that indicate changes to the user interface, and (2) transmitting the records to the first portion of code. The first portion of code responds to the messages by performing the specified changes to the user interface.

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: A method and apparatus identifies backup files that will restore a file in a transactional system. A reset stamp and filename is used to identify all backup files of the file having the filename since the file was last restored. A smaller number of files necessary to restore the file are selected from these backup files by sorting the list of files and selecting certain files in sort order. If necessary, earlier reset stamps are identified and more files are identified and selected, until a file is selected that contains a full backup or datafile copy of the file. For the backup files selected, information such as the location of the file is stored in the order in which the backup files are selected. The information, such as the location of each file selected, is provided in an order that is the reverse of the order in which the files were selected so that the oldest file is listed first. The files may be restored in the order provided.

Abstract: A file system configuration is scored by summing the squares of the sizes of each contiguous section of free space. A set of defragmentation plans, each describing a sequence of file movements, is generated and scored. The defragmentation plan with the highest score is chosen and executed. In moving a file, a temporary file of the same size is created and the file is copied to the temporary file. After the copying, the temporary file is designated as the file, and the file system space originally occupied by the file is unallocated.

Abstract: A method and apparatus for segmenting bitmaps in a bitmap index is provided. A segmented bitmap includes a plurality of bitmap segments that are used to indicate which records in a body of records that is associated with the segmented bitmap satisfy a particular criteria. Each bitmap segment contains a string of bits that correspond to a corresponding range of records in the body of records. There may be gaps between the ranges represented by the bitmap segments when, for example, the body of records does not contain records in a particular range. For the purposes of retrieval, compression, de-compression, locking and logging, the database system treats each bitmap segment as a distinct data item.

Abstract: The present invention pertains to an apparatus and process for storing information object collections in a database. Examples of such object collections are nested tables and variable length arrays. In an embodiment, the invention provides mechanisms and methods for storing nested tables in either a base table of a database, or an index-organized table. In one embodiment, mechanisms and methods are provided for storing variable length arrays into a table column, as a large object ("LOB"), or as an index-organized table. The invention also provides methods and mechanisms for accessing data from these storage mediums.

Abstract: A knowledge catalog includes a plurality of independent and parallel static ontologies to accurately represent a broad coverage of concepts that define knowledge. The actual configuration, structure and orientation of a particular static ontology is dependent upon the subject matter or field of the ontology in that each ontology contains a different point of view. The static ontologies store all senses for each word and concept. A knowledge classification system, that includes the knowledge catalog, is also disclosed. A knowledge catalog processor accesses the knowledge catalog to classify input terminology based on the knowledge concepts in the knowledge catalog. Furthermore, the knowledge catalog processor processes the input terminology prior to attachment in the knowledge catalog. The knowledge catalog further includes a dynamic level that includes dynamic hierarchies.

Abstract: A method and system for accessing a large object (LOB) that belongs to a cell in a table are provided. An index is built on a column in which the cell resides. The index has a key that includes a LOB identifier. A database server receives from a client a request to access the LOB. The server uses a LOB identifier value for the LOB to traverse the index to locate an index entry for the LOB. The server then follows address information contained in the index entry to a storage containing at least a portion of the LOB and accesses the portion of the LOB as specified in the request. A method and system for tracking storage for data items are also disclosed. Within an index that is built to access the data items are stored both index entries for locating blocks that store current versions of the data items, and index entries for locating blocks that store non-current versions of the data items.

Abstract: Communication costs are reduced in a distributed system that supports data replication with conflict detection by sending small values or nulls as replacements for field values that are not strictly used for replication or conflict detection. Specifically, nulls are propagated for new values of unmodified fields, old values of fields in unmodified groups of linked fields, and old values of fields for which conflict detection has been disabled. Flag values that indicate which actual old and new values were sent may be generated and propagated along with the replicated data.

Abstract: An advanced message queuing system is integrated into a database system. A queue is an ordered list of messages. Messages are requests for processing by an application. Messages are database objects and can represent events or data. Messages comprise user data and control information such as a queue name. Each queue is part of a table in a relational database. A queue table holds a set of queues. Dictionary tables store configuration information describing queues and queue tables. Messages are entered into a queue by instructing the database system using an enqueuing command attached to a message and control information. The control information describes how to order, schedule, and execute the message, and can include a result queue name into which a result message is written after execution. The system responds to a dequeuing command by delivering a copy of a message from the queue. A user can define message order within a queue, message delay factors, and exception processing.

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: A method and apparatus for coordinating access to a storage system in a real time processing system is disclosed. In an apparatus including a file server, a storage system, a real time process, and a non-real time process, an apparatus and method is disclosed for coordinating accesses to the storage system, the method includes the steps of: 1) computing an available data rate from a peak bandwidth data transfer rate for the storage system, 2) receiving a first access request from the real time process, the first access request including a request for a requested data rate, 3) granting the first access request if the requested data rate is less than or equal to the available data rate, and 4) allowing the real time process to directly access the storage system at the requested data rate.

Abstract: An auto resizing of fields system is disclosed that permits resizing a selected group of cells on a computer generated form. The selected group of cells are aligned, such as in a column, on a computer generated form. Data for the computer form is contained on records that may be stored at remote data sources. To auto size a selected group of cells, sample records are selected, and for each record selected, a display size large enough to display data without obstruction in the corresponding cell is calculated. From the display sizes calculated, a single optimal size for all cells in the group of cells is determined. Based on the optimal size, the group of cells are resized, and additional cells, which are visible on the computer generated form, are also resized to reflect the resizing of the group of cells. A technique for calculating an optimal width for a selected column on a form is also disclosed.

Abstract: A database server is configured to process original requests received from a client and callback requests received from an external routine. The database server saves global information before calling the external routine to distinguish whether a received request is an original or a callback request. Furthermore, both types of requests can be submitted via the same application programming interface and preferably with the same interprocess communication protocol.

Abstract: The present invention provides a uniqueness-required index and a corresponding non-uniqueness count to support deferred uniqueness constraint enforcement. A uniqueness-required index stores duplicate occurrences of indexed data values that occur during statement or transaction processing. The non-uniqueness count associated with the uniqueness-required index provides a count of the number of indexed data values that occur more than once in the index. Where a non-uniqueness count is not equal to zero, a uniqueness constraint violation remains unresolved. Where an unresolved constraint violation exists at enforcement time, the effects of the processing are removed. A currently non-unique count can be used to represent the number of uniqueness-required indexes that are "currently non-unique". The currently non-unique count can be examined to determine whether there are any unresolved uniqueness constraint violations.

Abstract: A method and apparatus for implementing a data construct, referred to herein as a "cursor variable", that has many of the attributes of simple variables and that can be used to access active sets of data from a database. Cursor variables identify a current set of data in an active set generated as a result of a database query. A cursor variable can be associated with any one of a number of different queries at any given time during program execution without using a host programming language. As a result, different active sets having different columns, different tables, and/or different predicates may be associated with the same cursor variable using instructions from a single programming language.