Abstract: Transactions are replicated from a source database to a target database in a data replication system. The system includes a first memory location that persistently stores statement text associated with transactions to be replicated. Transactions to be replicated are cached by separating the transactions into statement text and statement data. A determination is made as to whether the statement text has been previously stored in the first memory location. If not, then the statement text is persistently stored to the first memory location. A similar scheme is provided for replicating I/O operations.

Abstract: Response bubbles on a scannable form are provided that allow a user to mark the bubbles in a manner that signifies that the user wishes to have a response disregarded.

Abstract: A method is provided for resolving collisions in a database replication system. The system includes a source database and a target database, wherein changes made at the source database are replicated to the target database. Each database has one or more tables, and at least one of the tables has multiple constraints. A collision is detected during data replication as a result of one of the tables having multiple constraints. One constraint that contributes to the collision is identified. The constraint that contributes to the collision is relaxed, or the cause of the constraint that contributes to the collision is removed. This process is repeated for all additional constraints that contribute to the collision. In this manner, the collision is resolved.

Abstract: One or more response bubbles are used on a scannable form to be read by a scanning system. An unambiguous symbology of marks is defined to fill into each response bubble, thereby allowing at least one of a plurality of different non-empty intended responses having different output values to be entered into each response bubble. One or more response bubbles are provided on the scannable form to be filled in according to the defined symbology of unambiguous marks. A filled in form is scanned with the scanning system and an image of the scanned form is processed by identifying pixels associated with each response bubble, interpreting the pixels associated with each response bubble to define a raw score according to the defined unambiguous symbology of marks used to mark each response bubble, translating the raw score for each response bubble into one of the plurality of different intended non-empty responses, and outputting the value of the non-empty response for each response bubble.

Abstract: A method is provided of assigning processors in a multiprocessor environment to a plurality of processes that are executed in the multiprocessor environment. Each process has a process pair defined by a primary process that executes on a first processor, and a backup process that executes on a second processor. There are a plurality of process pairs. The processors are in communication with one another via a communication network. The processors are associated with a plurality of predefined processor pairs. First, a plurality of process pairs are provided that are initially assigned to a respective plurality of pairs of processors, wherein at least one of the processors in the plurality of pairs of processors is initially assigned to more than one processor pair. Each processor is then assigned to only one of the predefined processor pairs so that no processor belongs to more than one processor pair.

Abstract: Image data of a zone in a response form that has a plurality of response bubbles in the zone is processed. The image data of the zone has at least one response bubble that is well-formed and at least one response bubble that is not well-formed. Well-formed response bubbles are located in the zone from image data of the zone. The locations of the well-formed response bubbles in the zone are compared to a form template that defines the zone and contains data regarding locations of all expected response bubbles in the zone. It is determined from the comparison whether sufficient information exists to determine that the well-formed response bubbles constitute a specific part of the form template zone. If so, then the well-formed response bubbles are processed from the image data of the zone.

Abstract: Collisions are resolved in a database replication system. The system includes a plurality of nodes arranged in either a master-slave or network configuration. Each node includes a database, wherein changes made at the databases of each node are replicated to the databases at one or more of the other nodes. When a collision is detected during data replication between multiple nodes, the collision is resolved by a rule that gives precedence to certain nodes over other nodes.

Abstract: A method is provided of assigning processors in a multiprocessor environment to a plurality of processes that are executed in the multiprocessor environment. Each process has a process pair defined by a primary process that executes on a first processor, and a backup process that executes on a second processor. There are a plurality of process pairs. The processors are in communication with one another via a communication network. The processors are associated with a plurality of predefined processor pairs. First, a plurality of process pairs are provided that are initially assigned to a respective plurality of pairs of processors, wherein at least one of the processors in the plurality of pairs of processors is initially assigned to more than one processor pair. Each processor is then assigned to only one of the predefined processor pairs so that no processor belongs to more than one processor pair.

Abstract: A target database is synchronized with a source database in a database replication system. Key ranges of blocks of data to be replicated are used in the replication process. Also, synchronization occurs simultaneously with replication.

Abstract: A split processing system is provided that has a plurality of nodes and a communication network. Each node includes one or more processors, or a processor subsystem including at least one processor and an operating system. Each node has a specific number of failure modes which is less than the number of failure modes in an unsplit system wherein all of the processors are located at a single node. The communication network allows the one or more processors at each of the nodes to interoperate with each other.

Abstract: Tokens are used to prepare a target database for replication from a source database and to confirm the preparation in an asynchronous coordinated commit replication process. During a dual write replication process, transmission of the replicated data and locking of data records in the target database occurs only on updates.

Abstract: A method is provided for splitting a system comprising a processor subsystem including a plural number (np) of processors, and an instance of a database. A number (nn) of nodes is selected that the system is to be split into. Each node may be provided with a processor subsystem including at least one processor. At least some of the nodes further include an instance of at least a portion of the database. A network is provided for communications among the nodes. At least some of the nodes that contain an instance of at least a portion of the database are automatically synchronized so that contents of the database that exist in plural nodes remain synchronized in at least some of the plural nodes whenever contents of the database at one of the nodes is changed. Systems with multiple processors, but without databases, may also be split in the same manner.

Abstract: Database replication systems replicate blocks of transaction steps or operations with synchronous replication, and perform dual writes with queuing and blocking of transactions. Tokens are used to prepare a target database for replication from a source database and to confirm the preparation. Database replication systems switch between a synchronous replication mode and an asynchronous replication mode, and then back to a synchronous replication mode, based on detection of selected events.

Abstract: In a database synchronization process, a block of data is read from a source database at the first node. A marker is assigned to the block of data, and the marker is then written to an audit trail at the first node. The marker is sent from the audit trail to a second node having a target database. The block of data is sent from the first node to the second node without passing the block of data through the audit trail. At the second node, the block of data is stored in the target database upon receipt at the second node of the block of data and the marker assigned to the block of data. This process is repeated for additional blocks of data in the source database, wherein a marker is assigned to each subsequent block of data. In this manner, some or all of the source database may be replicated to the target database without having to store or pass any data in the source database in or through the audit trail at the first node.

Abstract: One or more response bubbles are used on a scannable form to be read by a scanning system. An unambiguous symbology of marks is defined to fill into each response bubble, thereby allowing at least one of a plurality of different responses to be entered into each response bubble. One or more response bubbles are provided on the scannable form to be filled in according to the defined symbology of unambiguous marks. A filled in form is scanned with the scanning system and an image of the scanned form is processed by identifying pixels associated with each response bubble, interpreting the pixels associated with each response bubble to define a raw score according to the defined unambiguous symbology of marks used to mark each response bubble, translating the raw score for each response bubble into one of the plurality of different responses, and outputting the response for each response bubble.

Abstract: A target database is synchronized with a source database in a database replication system. Key ranges of blocks of data to be replicated are used in the replication process. Also, synchronization occurs simultaneously with replication.

Abstract: Tokens are used to prepare a target database for replication from a source database and to confirm the preparation in an asynchronous coordinated commit replication process. During a dual write replication process, transmission of the replicated data and locking of data records in the target database occurs only on updates.

Abstract: In a database synchronization process, a block of data is read from a source database at the first node. A marker is assigned to the block of data, and the marker is then written to an audit trail at the first node. The marker is sent from the audit trail to a second node having a target database. The block of data is sent from the first node to the second node without passing the block of data through the audit trail. At the second node, the block of data is stored in the target database upon receipt at the second node of the block of data and the marker assigned to the block of data. This process is repeated for additional blocks of data in the source database, wherein a marker is assigned to each subsequent block of data. In this manner, some or all of the source database may be replicated to the target database without having to store or pass any data in the source database in or through the audit trail at the first node.

Abstract: A split processing system is provided that has a plurality of nodes and a communication network. Each node includes one or more processors, or a processor subsystem including at least one processor and an operating system. Each node has a specific number of failure modes which is less than the number of failure modes in an unsplit system wherein all of the processors are located at a single node. The communication network allows the one or more processors at each of the nodes to interoperate with each other.

Abstract: A bidirectional database replication system includes a plurality of nodes. Each transaction at an originating node is paused prior to a commit operation. Ready to commit tokens are sent to the other nodes in the system to determine if the other nodes are prepared for the commit operation for the paused transaction. If all of the ready to commit tokens properly return to the originating node from the other nodes, thereby indicating that the other nodes are prepared for the commit operation, then the transaction is commited. For lengthy transactions, ready to sync tokens are assigned at one or more predesignated intermediate points in the transaction, and propagate throughout the system in a similar manner. The transaction continues to execute as long as all ready to sync tokens properly return to the originating node. The pause-before-commit and sync point schemes are used to avoid collisions at any of the nodes.