Abstract: The SQL compiler and SQL executor in a database management system are extended to process queries requiring streaming mode processing of data stored in a table. A scan operator performs table access functions during execution of the streaming mode query. The scan operator first performs an initial scan to access rows in a specified database table, and then performs a delta scan to access new rows added to the table, as well as rows modified by other queries. The scan operator continues to process new data added to the table until the initiating user or application closes the associated cursor. A set of data structures are provided to keep track of active scan operators, including a session control block that includes fields for keeping track of whether the scan operator is performing an initial scan or a delta scan. The session control block also includes, for streaming mode scan operators, a delta scan list of new and modified rows to be processed in the delta scan.

Abstract: A database management system is extended to process SQL statements so as to skip over rows that are locked in conflicting modes. Normally, a table access operator is blocked when it attempts to access a row that is locked in a conflicting mode, such as a write lock mode, that is inconsistent with the read or write access required by the operator. Generally, the lock in the conflicting mode will be held by a transaction other than the transaction associated with the operator in question. When the SQL statement being executed uses the “skip conflict” syntax provided by the present invention, the operator skips over rows that are locked in conflicting modes, which would otherwise cause the operator to suspend operation. Furthermore, if the operator is operating in streaming mode, a key that identifies such skipped rows is added to the operator's list of rows to be processed at a later time.

Abstract: Systems and methods for ensuring that two different subordinate transactions will not be created at any given transaction processing node for the same parent transaction. Upon receiving a work request from a remote transaction processing system, the local transaction manager creates a local subordinate transaction associated with the parent transaction. A local transaction identifier that identifies the local subordinate transaction is also created. The local identifier includes an indicator, such as a one-bit flag, which identifies the local subordinate transaction as an imported transaction. The global identifier for the parent transaction is stored to a map in association with the transaction identifier of the new local subordinate transaction.

Abstract: A transaction processing system, including multiple processor units communicatively interconnected, manages information collection by employing a distributed transaction management facility to track and make consistent changes. When each transaction is started, a data structure is created that maintains information concerning the transaction. Included in the data structure is the identity of all processor units having resources involved in the transaction. Should a processor unit fail, and the transaction management facility is notified of that failure, the data structures of all pending transactions will be examined to see if the failed processor unit had a resource that was a participant in the corresponding transaction. If so, the transaction management facility can then make a decision as to whether or not to abort the transaction.

Abstract: Methods and systems for interoperating a transaction processing system implementing the presumed abort variation of the two-phase commit (2PC) protocol with a system implementing the presumed nothing variation. The gateway process that is responsible for exporting a transaction branch to a foreign transaction management system from a system implementing the presumed abort variation records whether the foreign transaction manager is implementing the presumed abort variation or the presumed nothing variation. After system failure, the gateway process determines which variation is adopted for a specific transaction branch. If the foreign transaction manager is implementing the presumed abort variation, the transaction manager from which the transaction branch originated communicates with the foreign transaction manager through the gateway process in accordance with the presumed abort variation.

Abstract: A distributed computation system has a set of agents that perform each specified distributed computation. State transition events in each agent are conditioned or dependent on state transition events in other ones of the agents participating in the same distributed computation. The event dependencies between events in the agents are dynamically specified at run time from a set of predefined dependency types. The assigned conditions for resolving the truth value of these events are stored in local knowledge databases in each of the agents. Each agent stores in its local knowledge database a representation of the conditions for local events, which are state transition events in that agent, and a representation of the conditions for those external events that depend on notifications of local events in this agent and for those external events on which the local events are dependent. The local knowledge database also stores status information on the current truth value of the local and external events.

Abstract: A protocol analysis system is provided with data specifying the defined states of processes participating in a distributed computation. State transitions between states are specified as being enabled by (A) receiving a message, (B) unreliably sending a message, or (C) performing an external action such as reliably sending a message. The specification data also identifies process states known to be final states, and all other states are initially denoted as intermediate states. The protocol analysis system determines if any intermediate states can be re-categorized as final states. Then it determines if any state transitions initially identified as unreliable send operations must be treated as derived external actions, and thus made reliable. Thirdly, for each derived external action, the states of the affected application process must be re-evaluated so as to determine if derived final states need to be converted into intermediate states.

Abstract: During the processing of a transaction or other distributed computation, a computation management system creates a number of agents to handle various aspects or portions of the computations to be performed. Each agent progresses through a predefined set of state transitions which define the status of the agent at any point in time. The computation management system defines for each agent a set of dependencies, each dependency corresponding to a state transition which will be blocked until a particular state transition occurs in another specified agent. By defining selected combinations of dependencies for each agent, a variety of different interdependencies and cooperating protocols can be implemented. The distributed processing management system can be used both for managing transaction processing and for synchronizing events in other types of distributed computations.

Abstract: A protocol analysis system is provided with data specifying the defined states of processes participating in a distributed computation. State transitions between states are specified as being enabled by (A) receiving a message, (B) unreliably sending a message, or (C) performing an external action such as reliably sending a message. The specification data also identifies process states known to be final states, and all other states are initially denoted as intermediate states. The protocol analysis system determines if any intermediate states can be re-categorized as final states. Then it determines if any state transitions initially identified as unreliable send operations must be treated as derived external actions, and thus made reliable. Thirdly, for each derived external action, the states of the affected application process must be re-evaluated so as to determine if derived final states need to be converted into intermediate states.

Abstract: A shaft seal assembly wherein the end portions of two coaxial shafts carry two components of a torque transmitting unit. One component is a disc which is eccentrically secured to the end portion of the respective shaft and extends into an eccentric circular recess of the other component which is coaxially affixed to the end portion of the associated shaft. A cup-shaped sealing element is installed in the recess to separate the two components from each other, and its annular portion is sealingly affixed to one end portion of a bellows whose other end portion is sealingly secured to one end wall of a housing. The shaft which carries the one component is rotatably journalled in the one end wall and the other shaft is rotatably journalled in a second end wall of the housing.

Abstract: Television circuit comprising a signal correction circuit which is active on signal recording and display, respectively, to obtain an optimum picture on display, and comprising a memory, memory-location (RC) containing correction information of which correspond to picture subregions (RC), each having their scanning lines (H1-H16), these subregions (RC) having been arranged in a matrix of rows and columns. According to the invention the memory comprises further memory locations (HOC) namely a first, further memory location (HOC1-HOC7) for each column of subregions, absolute correction information being present in each first further memory location for all subregions in the column and relative difference information being present in each memory location (R1C1-R19C7) corresponding to a subregion in the column, each relative difference information per subregion furnishing a correction information for each scanning line in the subregion which information is valid with respect to the preceding scanning line.

Abstract: A communication system comprising a connecting line and stations connected thereto, each station having free access to the connecting line. In a station which requests or has access, a transmitting stage and a receiving stage are both connected to the line, the output impedance of the transmitting stage on the supply of a predetermined logic value being temporarily increased to at least the order of magnitude of the characteristic impedance of the line, and a detector which is coupled to an output of the receiving stage producing a detection signal which switches off the transmitting station when the receiving stage receives a value which differs from the predetermined logic value.

Abstract: The accuracy of axial alignment of rotary shafts which are connected to each other by face gears is determined by micrometer screws which are moved into contact with annular control surfaces of the shafts. The control surfaces are normal to the axes of the respective shafts and, if their planes are not exactly parallel to each other, selected teeth of the mating face gears are elastically deformed to a greater or lesser extent to thereby tilt at least one of the shafts with respect to the other shaft until the two axes are accurately aligned with each other. The elastic deformation of selected gear teeth can be effected by bolts and nuts which connect the two shafts and extend in parallelism with their axes or by a composite annular clamp whose arcuate sections engage tapering surfaces on the flanges of the shafts and are held together by bolts which can tilt the shafts relative to each other by changing the width of gaps between neighboring sections.