38results about How to "Maintain data consistency" patented technology

The present invention provides a distributed clustering method to allow multiple active instances of consistency management processes that apply the same encoding scheme to be cooperative and function collectively. The techniques described herein facilitate an efficient method to apply an erasure encoding and decoding scheme across dispersed data stores that receive constant updates. The technique can be applied on many forms of distributed persistent data stores to provide failure resiliency and to maintain data consistency and correctness.

An efficient method to apply an erasure encoding and decoding scheme across dispersed data stores that receive constant updates. A data store is a persistent memory for storing a data block. Such data stores include, without limitation, a group of disks, a group of disk arrays, or the like. An encoding process applies a sequencing method to assign a sequence number to each data and checksum block as they are modified and updated onto their data stores. The method preferably uses the sequence number to identify data set consistency. The sequencing method allows for self-healing of each individual data store, and it maintains data consistency and correctness within a data block and among a group of data blocks. The inventive technique can be applied on many forms of distributed persistent data stores to provide failure resiliency and to maintain data consistency and correctness.

A writeable clone of a read-only dataset, e.g., an RPPI of a file system, a mirror file system, etc., is created to make the read-only dataset appear from a client's perspective to be modifiable/writeable, yet without actually modifying the read-only dataset itself. Any change attempted to be made on the read-only dataset is stored in the writeable clone. In one embodiment, the clone shares data blocks with the read-only dataset.

Methods and apparatus, including computer program products, implementing techniques for undoing user actions in a client program. The techniques include displaying a user interface in a client program, the user interface having a plurality of controls, the plurality of controls including multiple types of controls, each control having a state; for each control in the plurality of controls, storing the state of the control as a first state for the control; receiving user input comprising a change to the state of a control in the plurality of controls; updating the state of the control based on the user input; storing the updated state of the control as a second state for the control; receiving user input comprising a request to undo the change; and restoring the state of the control to reflect the first state for the control.

Disclosed is a system for replicating data. The system may comprise a plurality of nodes preferably organised in groups with one of the nodes acting as a coordinator node. The nodes are configured to receive write requests from an external server and to apply these write requests to a data storage source of the data storage system. The write requests typically belong to a batch of independent write actions identified by a batch sequence number. Each node stores the write request in non-volatile memory with the coordinator node monitoring which batches are secured in their entirety in non-volatile memory. The coordinator node authorises all other nodes to sequentially replicate the write requests in their non-volatile memory to the data storage source for all writes up to the highest batch sequence number for which all writes have been secured in non-volatile memory.

To improve the efficiency of access to a system memory associated with changes (writes) to cache data, a cache line having the same memory size as write data is selected and the write data is written into the selected cache line, thereby reducing the number of accesses to the system memory to cache data from the system memory associated with partial replacement of cache lines. Further, valid data at an address contiguous with the address of the write data is combined with the write data, and written into a cache line having the same size as the combined data, thereby reducing the number of accesses to the system memory to flush data from the cache associated with writes to the cache.

Novel methods are described herein to provide an OLAP database system that performs lock-less bulk insertion while maintaining high query performance and minimizing additional storage requirements. Aspects of the claimed subject matter include novel methods for merging two index structures while maintaining query consistency without the use of a versioning scheme by using copies of vertical segments of an index tree page; a method to prepare and merge two index structures that operates within storage constraints; and a method to execute queries concurrently while index maintenance is in progress while still producing consistent results. According to an aspect of the present disclosure, a flexible index merge mechanism is provided that merges data from incremental indices to a primary data index in three phases: a load phase, a copy phase, and a replace phase.

A memory card (100) is comprised of: a flash memory (120) that includes a plurality of physical blocks (122) made up of a plurality of pages for storing data and a page register (121) that holds data to be written to a page; and a controller (110) that specifies and erases an invalid physical block with reference to a valid block table (114) indicating whether valid data is stored in each of the physical blocks (122), when data is written, and that transfers, at the same time, the data to be written to the page register (121) while carrying out said erasure.

A method of testing cache coherency in a computer system design allocates different portions of a single cache line for use by accelerators and processors. The different portions of the cache line can have different sizes, and the processors and accelerators can operate in the simulation at different frequencies. The verification system can control execution of the instructions to invoke different modes of the coherency mechanism such as direct memory access or cache intervention. The invention provides a further opportunity to test any accelerator having an original function and an inverse function by allocating cache lines to generate an original function output, allocating cache lines to generate an inverse function output based on the original function output, and verifying correctness of the original and inverse functions by comparing the inverse function output to the original function input.

It is an object of the present invention to reduce output of a WAIT signal to maintain data consistency to effectively process subsequent memory access when there is no subsequent memory access in case of miss hit in a cache memory having a multi-stage pipeline structure. A cache memory according to the present invention performs update processing of a tag memory and a data memory and decides whether or not there is a subsequent memory access upon decision by a hit decision unit that an input address is a miss hit. Upon decision that there is a subsequent memory access, a controller outputs a WAIT signal to generate a pipeline stall for the pipeline processing of the processor to the processor, while the controller does not output a WAIT signal upon decision that there is no subsequent memory access.

A method of testing cache coherency in a computer system design allocates different portions of a single cache line for use by accelerators and processors. The different portions of the cache line can have different sizes, and the processors and accelerators can operate in the simulation at different frequencies. The verification system can control execution of the instructions to invoke different modes of the coherency mechanism such as direct memory access or cache intervention. The invention provides a further opportunity to test any accelerator having an original function and an inverse function by allocating cache lines to generate an original function output, allocating cache lines to generate an inverse function output based on the original function output, and verifying correctness of the original and inverse functions by comparing the inverse function output to the original function input.

The invention discloses a distributed system transaction management method and device. The method comprises the steps of: when a message sent by an active party node is received, carrying out storage on the message, marking a message state as a to-be-confirmed state, and sending a storage result of the message to the active party node; when an indication message sent by the active party node and used for indicating that a service operation is executed is received, updating the message state into a to-be-sent state; after the active party node executes the service operation, when a service operation result returned by the active party node is received, if the service operation result is that a service is successfully processed, sending the message to a passive party node, and updating the message state into a sent state; and after the passive party node executes the service operation, when a service operation result returned by the passive party node is that the service is failed in processing, sending the service operation result to the active party node and indicating the active party node to carry out a rolling-back operation. The method and the device which are disclosed by the invention achieve an effect of keeping consistency of data between the active party node and the passive party node.

A method for selecting a consensus protocol comprises separating a consensus protocol into one or more communication steps, wherein the consensus protocol is useable to substantially maintain data consistency between nodes in a distributed computing system, and wherein a communication step comprises a message transfer, attributable to the consensus protocol, in the distributed computing system, and computing an estimated protocol-level delay based on one or more attributes associated with the separated communication steps of the consensus protocol.

A memory system including a bus 10, 11, a memory 17, a memory controller 16, a first device 13 having a cache, and a second device 15, all connected to the bus, wherein the memory controller includes a buffer 20 for temporarily storing cache data and write data that the second device writes in the memory. The buffer of the memory controller temporarily stores cached data and the write data to be written on write access to the memory by the second device, which enables maintenance of data coherency while avoiding a write access retry by the second device.

The invention discloses a method and device for determining a data table association relationship, and relates to the technical field of computers. One specific embodiment of the method comprises thefollowing steps: S1, querying an associated field in a to-be-determined data table by utilizing an associated identifier, the associated field comprising a table name of the data table where an associated field associated with the associated field is located and the associated identifier, the associated field being a unique index of the data table where the associated field is located, and the associated field being an index of the to-be-determined data table; and S2, analyzing the associated fields, and obtaining the table names of the data tables where the associated fields corresponding tothe associated fields are located, so as to determine that the data tables are associated tables about the associated fields of the to-be-determined data tables. According to the embodiment, the change operation of the associated data table can be simplified, the application flexibility of the associated data table is improved, and meanwhile, the data consistency and integrity of the associated data table can be kept.

The present invention relates to a method for creating avatars from an initial sensitive data set stored in a database of a computer system, the initial data comprising attributes relating to a plurality of individuals, the method comprising: a) choosing a number {k} of nearest neighbors to be used from all the individuals in the initial data set, b) identifying, for attributes relating to a given individual, the k nearest neighbors from among the other individuals in the data set, c) generating, for at least one attribute relating to said individual, a new attribute value from quantities which are characteristic of the attribute in the identified k nearest neighbors and weighted by a coefficient, and d) creating avatar data comprising the new attribute value(s), so as to ensure the sensitive data relating to the individual are non-identifiable.

The invention provides a non-intrusive monitoring-oriented online load feature database maintenance method. According to the method, a service master station is taken as a central link, an interactionbridge between a client side and a monitoring side is set up, and the online real-time updating and maintenance problem of a non-intrusive monitoring load feature database is solved. A user can timely feed back addition of new load equipment to the service master station through a client side application, so the data consistency and expandability between a power utilization side and the monitoring side is maintained, the monitoring side can effectively identify various internal load types of the user, the powerful support for the user side load type identification accuracy is provided, the user is helped to optimize the power utilization, and the interaction management at the user side is prompted.