DATA COMMUNICATION OF MEANS OF AN UNRELIABLE ONE AND A RELIABLE TRANSPORT DEVICE

Parallel recovery by non-failed nodes

Disk writing operation in a distributed shared disk system

COMMUNICATION ARCHITECTURE FOR A DISTRIBUTED COMPUTER ENVIRONMENT

REDUCTION OF THE LATENCY AND COMMUNICATIONS DURING DATA AND BOLTING DEVICE TRANSMISSION IN A MULTI-KNOT SYSTEM

ADMINISTRATION OF THE REPLACEMENT OF DATA IN A HELPING MEMORY ON A KNOT DUE TO THE HELPING MEMORY OF THE OTHER KNOTS

Consistent read in a distributed database environment

Managing replacement of data in a cache on a node based on caches of other nodes

Caches on nodes in a cluster are globally managed so that a data item may be retained in any of the caches. A replacement policy that governs the replacement of data items stored in the caches selects buffers for replacement according to factors that include the state of the caches of other nodes. Some cached data items are designated as globally shared and assigned a primary cache. If a buffer holds a copy of a data item whose primary cache is another node, then the data item in the buffer is favored for replacement over a local data item or a global data item for which this is the primary cache. Cache retention values of buffers on different nodes may be compared. The buffer with the lowest cache retention value is selected for replacement. The replacement policy may also account for the way other caches in the cluster are configured.

CONSISTENT READINGS IN A DISTRIBUTED DATA BASE ENVIRONMENT

TO IMPLEMENT PROCEDURE AND DEVICE AROUND A DISTRIBUTED TRANSACTION IN A DISTRIBUTED DATA BASE

Communication architecture for distributed computing environment

Disk writes in a distributed shared disk system

Managing replacement of data in a cache on a node based on caches of other nodes

Reducing latency and message traffic during data and lock transfer in a multi-node system

Managing checkpoint queues in a multiple node system

Parallel recovery by non-failed nodes

KOMMUNIKATIONSARCHITEKTUR FÜR EINE VERTEILTE RECHNERUMGEBUNG

VERWALTUNG DER ERSETZUNG VON DATEN IN EINEM HILFSPEICHER AUF EINEM KNOTEN AUFGRUND DER HILFSPEICHERN ANDERER KNOTEN

Transmitting data reliably and efficiently

One-phase commit in a shared-nothing database system

One-phase commit in a shared-nothing database system

Communication architecture for distributed computing environment

REDUZIERUNG DER LATENZZEIT UND NACHRICHTENVERKEHR BEI DATEN- UND VERRIEGELUNGSÜBERTRAGUNG IN EINEM MEHRKNOTENSYSTEM

Managing checkpoint queues in a multiple node system

Transmitting data reliably and efficiently

Method and mechanism for batch processing transaction logging records

A method and mechanism is disclosed for implementing transaction logging in a database system. In-memory undo records are maintained to log undo information for the database system. Redo records are batch processed, with multiple redo records for a transaction stored on disk at commit time.

Verfahren und Vorrichtung um eine verteilte Transaktion in einer verteilten Datenbank auszuführen

KOMMUNIKATIONSARCHITEKTUR FÜR EINE VERTEILTE RECHNERUMGEBUNG

Managing replacement of data in a cache on a node based on caches of other nodes

A mechanism is described for managing the caches on nodes in a cluster. The caches are globally managed so that a data item may be retained in any cache on the nodes. This may be accomplished by, for example, a replacement policy for replacing data items stored in the buffers of the caches, where a buffer is selected for replacement in a manner that accounts for factors that include the state of the caches of other nodes. Some cached data items are designated as globally shared, and assigned (either statically or dynamically) a primary cache. For example, if a buffer holds a copy of a data item whose primary cache is another node, then the data item in the buffer is favored for replacement over a local data item or a global data item for which this is the primary cache. According to another aspect of the invention, the cache retention value of buffers on different nodes are compared, and the buffer with the lowest cache retention value is selected for replacement. According to yet another ...

Datenübertragung mittels einer unzuverlässigen und einer zuverlässigen Transportvorrichtung

Communication architecture for distributed computing environment

A communication architecture for performing work in a distributed computing environment involves client processes on client nodes sending work requests to a director. The director examines the work requests to determine one or more resources required to perform the work as well as one or more server nodes that can provide the required resources. The director then forwards the work requests to server processes on the server nodes that can provide the required resources. The work requests provided to the server processes specify that the work results are to be provided directly from the server processes to the client processes that made the work requests. The director maintains a table of resource data that specifies the services and/or resources that are provided by and/or made available on the server nodes in the distributed computing environment.

KONSISTENTE LESEVORGÄNGE IN EINER VERTEILTEN DATENBANKUMGEBUNG

KONSISTENTE LESEVORGÄNGE IN EINER VERTEILTEN DATENBANKUMGEBUNG

Performance-based caching

A method and system are provided for caching data in a manner that substantially maintains a desired level of system performance. A cache server receives data requests on behalf of a data server. When new data on the data server is generated or stored that replaces or changes data cached on the cache server, the corresponding data on the cache server is invalidated. A subsequent request for the new data may be forwarded to the data server or may be served with the invalid data on the cache server. Determining how to serve the request may depend on a possible impact on system performance and/or one or more characteristics or parameters associated with the requested data. The impact on system performance may be determined by examining actual and/or desired operating conditions (e.g., rate or number of requests, load on the data server, response time to requests, number of open connections, throughput). The data parameters that may be considered may include the popularity of the data; frequency ...

Verfahren und Vorrichtung um eine verteilte Transaktion in einer verteilten Datenbank auszuführen

Datenübertragung mittels einer unzuverlässigen und einer zuverlässigen Transportvorrichtung

METHOD FOR MANAGING INFORMATION ABOUT WHERE FAILURE IS RECOVERED AFTER FAILURE, METHOD FOR RECOVERY AFTER FAILURE, AND METHOD FOR RECOVERING CURRENT VERSION OF DATA ITEM AFTER FAILURE IN SYSTEM INCLUDING MULTIPLE CACHES

PROBLEM TO BE SOLVED: To provide techniques for managing caches in a system with multiple caches that may contain different copies of the same data item. SOLUTION: Entry for data items is removed from a single failure queue without removing entry for the data items from the multiple failure queue in response to a dirty data item being transmitted from a multi-node system to another node. Entries for data items are removed from both queues in response to the dirty data item being written in a persistent storage device. COPYRIGHT: (C)2009,JPO&INPIT ...

VERWALTUNG DES ERSETZENS VON DATEN IN EINEM ZWISCHENSPEICHER AUF EINEM KNOTEN AUFGRUND VON ZWISCHENSPEICHERN ANDERER KNOTEN

用于在多节点系统内数据和锁定传送期间减少潜伏时间和信息业务的技术

... 本发明提供一种方法和装置，用于改进与传送数据项相关的性能，并通过将块传送消息认作锁定授权消息来获得多节点系统中的锁定。一般地，当数据项的持有者将数据项传送(例如块)传送至该数据项的请求者时，持有者将下向转换其对该数据项的锁定，并向该数据项的主管发送一条消息，表明下向转换已经被进行。随后，主管向该数据项的请求者发送一条锁定授权消息，以通知请求者其已经授予对该数据项的锁定。通过将块传送消息认作锁定授权消息，就可消除该下向转换消息及锁定授权消息，从而改进性能。 ...

Disk writing operation in a distributed shared disk system

Ownership reassignment in a shared-nothing database system

Method and apparatus for reducing latency and message traffic during data and lock transfer in a multi-node system

A method and apparatus are provided for improving the performance associated with transferring a data item and obtaining a lock in a multi-node system by interpreting the block transfer message as a lock grant message. Typically when a Holder of a data item transfers a data item (e.g. block) to a Requestor of that data item, the Holder will down-convert its lock for that data item and send a message to the Master of this data item indicating that a down-convert has been performed. Subsequently, the Master sends a lock grant message to the Requestor of the data item to inform the Requestor that it has been granted a lock for the data item. By interpreting the block transfer message as a lock grant message, the down-convert message and the lock grant message can be eliminated, which results in improved performance.

Parallel recovery by non-failed nodes

Various techniques are described for improving the performance of a shared-nothing database system in which at least two of the nodes that are running the shared-nothing database system have shared access to a disk. Specifically, techniques are provided for recovering the data owned by a failed node using multiple recovery nodes operating in parallel. The data owned by a failed node is reassigned to recovery nodes that have access to the shared disk on which the data resides. The recovery logs of the failed node are read by the recovery nodes, or by a coordinator process that distributes the recovery tasks to the recovery nodes.

I/o forwarding in a cache coherent shared disk computer system

A method and apparatus for I/O forwarding in a cache coherent shared disk computer system is provided. According to the method, a requesting node transmits a request for requested data to a managing node. The managing node receives the read request from the requesting node and grants a lock on the requested data. The managing node then forwards data that identifies the requested data to a disk controller. The disk controller receives the data that identifies the requested data from the managing node and reads a data item, based on the data that identifies the requested data, from a shared disk. After reading the data item from the shared disk, the disk controller transmits the data item to the requesting node. In one embodiment, an I/O destination handle is generated that identifies a read request and a buffer cache address to which the data item should be copied. The I/O destination handle is transmitted to the disk controller to facilitate transmission and processing of the data item from the disk controller to the requesting node. As a result of forwarding data that identifies the requested data directly from the managing node to the disk controller ("I/O forwarding"), the duration of a stall is reduced, contention on resources of the system is reduced and a context switch is eliminated.

Consistent read in a distributed database environment

Techniques are provided for supplying a data item to a query that must see a particular snapshot of a database. For a plurality of data item versions that reside in a plurality of nodes, CLONE-TIME information is maintained that indicates when for each data item version of the plurality of data item versions, a clone branch to which the data item version belongs, is cloned from the current version of a data item; it is determined which data item versions of the plurality of data item versions contain all changes that must be seen by the query based, at least in part, on the CLONE-TIME information; and a data item version is selected to supply to the query from those data item versions that contain all changes that must be seen by the query.

Ownership reassignment in a shared-nothing database system

Various thechniques are described for improving the performance of a shared-nothing database system in which at least two of the nodes that are running the shared-nothing database system have shared access to a disk. Specifically, techniques are provided for changing the ownership of data in a shared-nothing database without changing the location of the data on persistent storage. Because the persistent storage location for the data is not changed during a transfer of ownership of the data, ownership can be transferred more freely and with less of a performance penalty than would otherwise be incurred by a physical relocation of the data. Various techniques are also described for providing fast run-time reassignment of ownership. Because the reassignment can be performed during run-time, the shared-nothing system does not have to be taken offline to perform reassignment. Further, the techniques describe how the reassignment can be performed with relatively fine granularity, avoiding the need to perform bulk reassignment of large amounts of data across all nodes merely to reassign ownership of a few data items on one of the nodes.

Providing a useable version of the data item

Techniques are provided for providing a data item to a transaction in a multi-versioning system in which the data item may exist on multiple versions of a data block, and were versioning is performed at the granularity of the data block. According to one aspect of the invention, the technique involves locating, within volatile memory, a first version of a data block that includes a first version of the data item. It is then determined whether the first version of the data item is usable by the transaction without respect to whether the first version of the data block is generally usable by the transaction. If the first version of the data item is usable by the transaction, then the data item is established as a candidate that can be provided to the transaction. Thus, the data item within a block may be considered a candidate to be provided to a transaction even when the version of the data block on which the data item resides would otherwise disqualify the data block from being seen by that transaction. If the first version of the data item is not usable by the transaction, then a version of the data item that is usable by the transaction is obtained from a second version of the data block that is different from the first version.

Dynamic reassignment of data ownership

Various techniques are described for improving the performance of a shared-nothing database system in which at least two of the nodes that are running the shared-nothing database system have shared access to a disk. Specifically, techniques are provided for changing the ownership of data in a shared-nothing database dynamically, based on factors such as which node would be the most efficient owner relative to the performance of a particular operation. Once determined, the ownership of the data may be changed permanently to the new owner, or temporarily for the duration of the particular operation.

Transmitting data reliably and efficiently

A method and mechanism is described for reliably transmitting messages over an unreliable transport mechanism. A sender transmits a first message over an unreliable mechanism to a receiver, and a second message that identifies the first is transported over a reliable transport mechanism to the receiver. When the receiver receives the second message, the receiver determines whether it has received the first message. If not, the receiver requests retransmission of the first message.

Transferring a resource from a first cache to a second cache

A method and apparatus are provided for transferring a resource from the cache of one database server to the cache of another database server without first writing the resource to disk. When a database server (Requestor) desires to modify a resource, the Requestor asks for the current version of the resource. The database server that has the current version (Holder) directly ships the current version to the Requestor. Upon shipping the version, the Holder loses permission to modify the resource, but continues to retain the resource in memory. When the retained version of the resource, or a later version thereof, is written to disk, the Holder can discard the retained version of the resource. Otherwise, the Holder does not discard the retained version. Using this technique, single-server failures are recovered without having to merge the recovery logs of the various database servers that had access to the resource.

Methods to perform disk writes in a distributed shared disk system needing consistency across failures

Techniques are provided for managing caches in a system with multiple caches that may contain different copies of the same data item. Specifically, techniques are provided for coordinating the write-to-disk operations performed on such data items to ensure that older versions of the data item are not written over newer versions, and to reduce the amount of processing required to recover after a failure. Various approaches are provided in which a master is used to coordinate with the multiple caches to cause a data item to be written to persistent storage. Techniques are also provided for managing checkpoints associated with the caches, where the checkpoints are used to determine the position at which to begin processing recovery logs in the event of a failure.

Insertion rate aware b-tree

Systems, methods, and other embodiments associated with insertion rate responsive b-trees are described. One system embodiment includes a capacity logic to detect a divide condition for a leaf node and an insert logic to determine an insertion level for the leaf node. The system embodiment may include an allocation logic to selectively allocate a set of leaf nodes. Characteristics of the set (e.g., number of members) may depend on the divide condition and the insertion level. The system embodiment may include a partition logic to move a partition key from the leaf node to a parent and to associate the partition key with the set of leaf nodes. A fuzzy index logic may provide key-based addressing to the set of leaf nodes.

Consistent read in a distributed database environment

Techniques are provided for determining which data item version to supply to a query. According to the techniques, the determination is made by associating a new field, which indicates the time a data item version was current, with each data item version; associating a new field with each query, which indicates the last change that the query must see made by the transaction to which the query belongs; and determining which data item version to use to answer the query based, in part, on a comparison between the values of the two new fields.

Managing checkpoint queues in a multiple node system

Techniques are provided for managing caches in a system with multiple caches that may contain different copies of the same data item. Specifically, techniques are provided for coordinating the write-to-disk operations performed on such data items to ensure that older versions of the data item are not written over newer versions, and to reduce the amount of processing required to recover after a failure. Various approaches are provided in which a master is used to coordinate with the multiple caches to cause a data item to be written to persistent storage. Techniques are also provided for managing checkpoints associated with the caches, where the checkpoints are used to determine the position at which to begin processing recovery logs in the event of a failure.

Reducing latency and message traffic during data and lock transfer in a multi-node system

Consistent read in a distributed database environment

Managing checkpoint queues in a multiple node system

Techniques are provided for managing caches in a system with multiple caches that may contain different copies of the same data item. Specifically, techniques are provided for coordinating the write-to-disk operations performed on such data items to ensure that older versions of the data item are not written over newer versions, and to reduce the amount of processing required to recover after a failure. Various approaches are provided in which a master is used to coordinate with the multiple caches to cause a data item to be written to persistent storage. Techniques are also provided for managing checkpoints associated with the caches, where the checkpoints are used to determine the position at which to begin processing recovery logs in the event of a failure.

Object hashing with incremental changes

A method and system are provided for reconfiguring a multiple node system after an epoch change in a manner that reduces the overhead and system unavailability typically incurred during reconfiguration. A resource-to-master mapping is established using the combination of a resource-to-bucket hash function and a buket-to-node hash function. The resource-to-bucket hash function is not changed in response to an epoch change. The bucket-to-node hash function does change in response to epoch changes. Techniques are disclosed for adjusting the dynamic bucket-to-node hash function after an epoch change in a manner that load balances among the new number of nodes in the system. Further, the changes to the bucket-to-node assignments are performed in a way that reduces the number of resources that have to be remastered. In one embodiment, only those resources that lose their masters during an epoch change are assigned new masters during an initial reconfiguration. Load balancing is then gradually achieved by migrating resources after the system has been made available. The old masters of resources forward access requests to new masters of resources once they have transferred the master resource objects for the requested resources. In addition, techniques are disclosed for migrating resources from a node in anticipation of a planned shutdown of the node.

Method and apparatus for transferring data from the cache of one node to the cache of another node

A method and apparatus are provided for transferring a resource from the cache of one database server to the cache of another database server without first writing the resource to disk. When a database server (Requestor) desires to modify a resource, the Requestor asks for the current version of the resource. The database server that has the current version (Holder) directly ships the current version to the Requestor. Upon shipping the version, the Holder loses permission to modify the resource, but continues to retain the resource in memory. When the retained version of the resource, or a later version thereof, is written to disk, the Holder can discard the retained version of the resource. Otherwise, the Holder does not discard the retained version. Using this technique, single-server failures are recovered without having to merge the recovery logs of the various database servers that had access to resource.

I/O forwarding in a cache coherent shared disk computer system

One-phase commit in a shared-nothing database system

Techniques are provided for handling distributed transaction in shared-nothing database system where one or more of the nodes have access to a shared persistent storage. Rather than coordinate the distributed transaction using a two-phase commit protocol, the coordinator of the distributed transaction uses a one-phase commit protocol with those participants that have access to the transaction status information maintained by the coordinator. The transaction status information may reside, for example, in the redo log of the coordinator. In case that the coordinator fails, those participants can determine the state of the distributed transaction based on information stored on the shared disk. In addition, the coordinator is able to determine whether it is possible to commit the distributed transaction based on information that is stored on the shared disk by the participants, without those participants entering a formal "prepared " state.

Managing a resource used by a plurality of nodes

A method and apparatus are provided for transferring a resource from the cache of one database server to the cache of another database server without first writing the resource to disk. When a database server (Requestor) desires to modify a resource, the Requestor asks for the current version of the resource. The database server that has the current version (Holder) directly ships the current version to the Requestor. Upon shipping the version, the Holder looses permission to modify the resource, but continues to retain the resource in memory. When the retained version of the resource, or a later version thereof, is written to disk, the Holder can discard the retained version of the resource. Otherwise the Holder does not discard the retained version. Using this technique, single-server failures are recovered without having to merge the recovery logs of the various database servers that had access to the ressource.

Disk writes in a distributed shared disk system

Techniques are provided for managing caches in a system with multiple caches that may contain different copies of the same data item. Specifically, techniques are provided for coordinating the write-to-disk operations performed on such data items to ensure that older versions of the data item are not written over newer versions, and to reduce the amount of processing required to recover after a failure. Various approaches are provided in which a master is used to coordinate with the multiple caches to cause a data item to be written to persistent storage. Techniques are also provided for managing checkpoints associated with the caches, where the checkpoints are used to determine the position at which to begin processing recovery logs in the event of a failure.

Ownership reassignment in a shared-nothing database system

Parallel recovery by non-failed nodes

Various techniques are described for improving the performance of a shared-nothing database system in which at least two of the nodes that are running the shared-nothing database system have shared access to a disk. Specifically, techniques are provided for recovering the data owned by a failed node using multiple recovery nodes operating in parallel. The data owned by a failed node is reassigned to recovery nodes that have access to the shared disk on which the data resides. The recovery logs of the failed node are read by the recovery nodes, or by a coordinator process that distributes the recovery tasks to the recovery nodes.

Method and apparatus for transferring data from the cache of one node to the cache of another node

A method and apparatus are provided for transferring a resource from the cache of one database server to the cache of another database server without first writing the resource to disk. When a database server (Requestor) desires to modify a resource, the Requestor asks for the current version of the resource. The database server that has the current version (Holder) directly ships the current version to the Requestor. Upon shipping the version, the Holder loses permission to modify the resource, but continues to retain the resource in memory. When the retained version of the resource, or a later version thereof, is written to disk, the Holder can discard the retained version of the resource. Otherwise, the Holder does not discard the retained version. Using this technique, single-server failures are recovered without having to merge the recovery logs of the various database servers that had access to the resource.

Method and apparatus for transferring data from the cache of one node to the cache of another node

A method and apparatus are provided for transferring a resource from the cache of one database server to the cache of another database server without first writing the resource to disk. When a database server (Requestor) desires to modify a resource, the Requestor asks for the current version of the resource. The database server that has the current version (Holder) directly ships the current version to the Requestor. Upon shipping the version, the Holder loses permission to modify the resource, but continues to retain the resource in memory. When the retained version of the resource, or a later version thereof, is written to disk, the Holder can discard the retained version of the resource. Otherwise, the Holder does not discard the retained version. Using this technique, single-server failures are recovered without having to merge the recovery logs of the various database servers that had access to the resource.

Managing replacement of data in a cache on a node based on caches of other nodes

Caches on nodes in a cluster are globally managed so that a data item may be retained in any of the caches. A replacement policy that governs the replacement of data items stored in the caches selects buffers for replacement according to factors that include the state of the caches of other nodes. Some cached data items are designated as globally shared and assigned a primary cache. If a buffer holds a copy of a data item whose primary cache is another node, then the data item in the buffer is favored for replacement over a local data item or a global data item for which this is the primary cache. Cache retention values of buffers on different nodes may be compared. The buffer with the lowest cache retention value is selected for replacement. The replacement policy may also account for the way other caches in the cluster are configured.

Providing a useable version of the data item

Method and apparatus for transferring data from the cache of one node to the cache of another node

A method and apparatus are provided for transferring a resource from the cache of one database server to the cache of another database server without first writing the resource to disk. When a database server (Requestor) desires to modify a resource, the Requestor asks for the current version of the resource. The database server that has the current version (Holder) directly ships the current version to the Requestor. Upon shipping the version, the Holder loses permission to modify the resource, but continues to retain the resource in memory. When the retained version of the resource, or a later version thereof, is written to disk, the Holder can discard the retained version of the resource. Otherwise, the Holder does not discard the retained version. Using this technique, single-server failures are recovered without having to merge the recovery logs of the various database servers that had access to the resource.

Datenübertragung mittels einer unzuverlässigen und einer zuverlässigen transportvorrichtung

Managing replacement of data in a cache on a node based on caches of other nodes

Managing replacement of data in a cache on a node based on caches of other nodes

Caches on nodes in a cluster are globally managed so that a data item may be retained in any of the caches. A replacement policy that governs the replacement of data items stored in the caches selects buffers for replacement according to factors that include the state of the caches of other nodes. Some cached data items are designated as globally shared and assigned a primary cache. If a buffer holds a copy of a data item whose primary cache is another node, then the data item in the buffer is favored for replacement over a local data item or a global data item for which this is the primary cache. Cache retention values of buffers on different nodes may be compared. The buffer with the lowest cache retention value is selected for replacement. The replacement policy may also account for the way other caches in the cluster are configured.

Managing replacement of data in a cache on a node based on caches of other nodes

Caches on nodes in a cluster are globally managed so that a data item may be retained in any of the caches. A replacement policy that governs the replacement of data items stored in the caches selects buffers for replacement according to factors that include the state of the caches of other nodes. Some cached data items are designated as globally shared and assigned a primary cache. If a buffer holds a copy of a data item whose primary cache is another node, then the data item in the buffer is favored for replacement over a local data item or a global data item for which this is the primary cache. Cache retention values of buffers on different nodes may be compared. The buffer with the lowest cache retention value is selected for replacement. The replacement policy may also account for the way other caches in the cluster are configured.

基於其他節點上的緩存而管理一個節點上緩存的資料的置換

Verwaltung der ersetzung von daten in einem hilfspeicher auf einem knoten aufgrund der hilfspeichern anderer knoten

Kommunikationsarchitektur für eine verteilte rechnerumgebung

使用多節點對資源進行管理

用於分佈計算環境的通信結構

Managing recovery of data after failure of one or more caches

Recovering data from a failed cache using a surviving cache

A method and apparatus are provided for transferring a resource from the cache of one database server to the cache of another database server without first writing the resource to disk. When a database server (Requestor) desires to modify a resource, the Requestor asks for the current version of the resource. The database server that has the current version (Holder) directly ships the current version to the Requestor. Upon shipping the version, the Holder loses permission to modify the resource, but continues to retain the resource in memory. When the retained version of the resource, or a later version thereof, is written to disk, the Holder can discard the retained version of the resource. Otherwise, the Holder does not discard the retained version. Using this technique, single-server failures are recovered without having to merge the recovery logs of the various database servers that had access to the resource.

Verwaltung eines durch eine Mehrzahl von Knoten benutzten Betriebsmittels

Recovering data from a failed cache using recovery logs of caches that updated the data

A method and apparatus are provided for transferring a resource from the cache of one database server to the cache of another database server without first writing the resource to disk. When a database server (Requestor) desires to modify a resource, the Requestor asks for the current version of the resource. The database server that has the current version (Holder) directly ships the current version to the Requestor. Upon shipping the version, the Holder loses permission to modify the resource, but continues to retain the resource in memory. When the retained version of the resource, or a later version thereof, is written to disk, the Holder can discard the retained version of the resource. Otherwise, the Holder does not discard the retained version. Using this technique, single-server failures are recovered without having to merge the recovery logs of the various database servers that had access to the resource.

Übertragung von Betriebsmitteln von einem Cache zu einem zweiten Cache

Datenrückgewinnungsverwaltung nach Ausfall von einem oder mehreren Caches

Transferring a resource from a first cache to a second cache

Transferring a resource between caches of different nodes

A method and apparatus are provided for transferring a resource from the cache of one database server to the cache of another database server without first writing the resource to disk. When a database server (Requestor) desires to modify a resource, the Requestor asks for the current version of the resource. The database server that has the current version (Holder) directly ships the current version to the Requestor. Upon shipping the version, the Holder loses permission to modify the resource, but continues to retain the resource in memory. When the retained version of the resource, or a later version thereof, is written to disk, the Holder can discard the retained version of the resource. Otherwise, the Holder does not discard the retained version. Using this technique, single-server failures are recovered without having to merge the recovery logs of the various database servers that had access to the resource.

Method and apparatus for transferring data from the cache of one node to the cache of another node

Verwaltung eines durch eine Mehrzahl von Knoten benutzten Betriebsmittels

Method and apparatus for transferring data from the cache of one node to the cache of another node

A method and apparatus are provided for transferring a resource from the cache of one database server to the cache of another database server without first writing the resource to disk. When a database server (Requestor) desires to modify a resource, the Requestor asks for the current version of the resource. The database server that has the current version (Holder) directly ships the current version to the Requestor. Upon shipping the version, the Holder loses permission to modify the resource, but continues to retain the resource in memory. When the retained version of the resource, or a later version thereof, is written to disk, the Holder can discard the retained version of the resource. Otherwise, the Holder does not discard the retained version. Using this technique, single-server failures are recovered without having to merge the recovery logs of the various database servers that had access to the resource.

一個或多個高速緩存失敗後恢復數據的管理

從一個或多個失敗的高速緩存恢復數據

Rückgewinnung von Daten von einem oder mehreren fehlerhaften Caches

Konsistente lesevorgänge in einer verteilten datenbankumgebung

Managing a resource used by a plurality of nodes.

Disk writes in a distributed shared disk system

Techniques are provided for managing caches in a system with multiple caches that may contain different copies of the same data item. Specifically, techniques are provided for coordinating the write-to-disk operations performed on such data items to ensure that older versions of the data item are not written over newer versions, and to reduce the amount of processing required to recover after a failure. Various approaches are provided in which a master is used to coordinate with the multiple caches to cause a data item to be written to persistent storage. Techniques are also provided for managing checkpoints associated with the caches, where the checkpoints are used to determine the position at which to begin processing recovery logs in the event of a failure.

Reduzierung der latenzzeit und nachrichtenverkehr bei daten- und verriegelungsübertragung in einem mehrknotensystem

Verfahren und vorrichtung um eine verteilte transaktion in einer verteilten datenbank auszuführen

Dynamic reassignment of data ownership

Managing replacement of data in a cache on a node based on caches of other nodes

Caches on nodes in a cluster are globally managed so that a data item may be retained in any of the caches. A replacement policy that governs the replacement of data items stored in the caches selects buffers for replacement according to factors that include the state of the caches of other nodes. Some cached data items are designated as globally shared and assigned a primary cache. If a buffer holds a copy of a data item whose primary cache is another node, then the data item in the buffer is favored for replacement over a local data item or a global data item for which this is the primary cache. Cache retention values of buffers on different nodes may be compared. The buffer with the lowest cache retention value is selected for replacement. The replacement policy may also account for the way other caches in the cluster are configured.

Methods to perform disk writes in a distributed shared disk system needing consistency across failures

Techniques are provided for managing caches in a system with multiple caches that may contain different copies of the same data item. Specifically, techniques are provided for coordinating the write-to-disk operations performed on such data items to ensure that older versions of the data item are not written over newer versions, and to reduce the amount of processing required to recover after a failure. Various approaches are provided in which a master is used to coordinate with the multiple caches to cause a data item to be written to persistent storage. Techniques are also provided for transferring data items and locks associated with the data items from one node to another.