Managing replacement of data in a cache on a node based on caches of other nodes
    5.
    发明授权
    Managing replacement of data in a cache on a node based on caches of other nodes 有权
    基于其他节点的缓存管理节点上的缓存中的数据替换

    公开(公告)号:US06633891B1

    公开(公告)日:2003-10-14

    申请号:US09652384

    申请日:2000-08-31

    IPC分类号: G06F1730

    摘要: 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 aspect of the present invention, the replacement policy accounts for the configuration of other caches in the cluster.

    摘要翻译: 描述了一种用于管理群集中节点上的高速缓存的机制。 高速缓存被全局管理,使数据项可以保留在节点上的任何高速缓存中。 这可以通过例如用于替换存储在高速缓存的缓冲器中的数据项的替换策略来实现,其中以考虑到包括其他节点的高速缓存的状态的因素的方式选择用于替换的缓冲器。 一些缓存的数据项被指定为全局共享,并被分配(静态地或动态地)主缓存。 例如,如果缓冲器保存其主缓存是另一个节点的数据项的副本,则缓冲器中的数据项有利于替换本地数据项或作为主缓存的全局数据项。 根据本发明的另一方面,比较不同节点上的缓冲器的缓存保留值,并选择具有最低缓存保留值的缓冲器进行替换。 根据本发明的另一方面,替换策略考虑了集群中其他高速缓存的配置。

    Two-pass multi-version read consistency
    6.
    发明授权
    Two-pass multi-version read consistency 失效
    双通多版本读取一致性

    公开(公告)号:US5452445A

    公开(公告)日:1995-09-19

    申请号:US876626

    申请日:1992-04-30

    IPC分类号: G06F12/00 G06F17/30 G06F15/40

    摘要: The present invention describes a method and apparatus that forces all parts of an update transaction to commit automatically using a two-phase commit. The present invention uses the two-phase commit messages to negotiate a system commit number (SCN) that is then recorded on each of the nodes as the logical point in time that the distributed transaction committed. The two-phase commit scheme of the present invention consists of a "prepare" phase and a "commit" phase. The transaction in the distributed database environment involves multiple participants (databases). In the prepare phase, one of the N database participants is selected as the "commit point." The commit point includes the log into which the information is written that states the transaction has committed. The remaining N-1 participants enter a "prepare phase." In the prepare phase, the prepare participants lock their databases and enter a state in which they are ready to roll back or commit to the transaction. The mid-point of the two-phase commit is the point at which the commit point database (nth participant) writes the commit transaction to its log. In the second phase, the remaining participants are informed to commit the transaction and release locks that have been set.

    摘要翻译: 本发明描述了一种使用两阶段提交来强制更新事务的所有部分自动提交的方法和装置。 本发明使用两阶段提交消息来协商随后记录在每个节点上的系统提交号(SCN)作为分布式事务提交的逻辑时间点。 本发明的两阶段提交方案由“准备”阶段和“提交”阶段组成。 分布式数据库环境中的事务涉及多个参与者(数据库)。 在准备阶段,选择N个数据库参与者之一作为“提交点”。 提交点包括描述交易已提交的信息的日志。 其余的N-1参与者进入“准备阶段”。 在准备阶段,准备参与者锁定其数据库,并进入他们准备回滚或提交交易的状态。 两阶段提交的中点是提交点数据库(第n个参与者)将提交事务写入其日志的点。 在第二阶段,剩余的参与者被通知提交交易并释放已设置的锁。

    Sharing snapshots for consistent reads
    7.
    发明授权
    Sharing snapshots for consistent reads 失效
    共享快照以进行一致的读取

    公开(公告)号:US5956731A

    公开(公告)日:1999-09-21

    申请号:US842169

    申请日:1997-04-23

    IPC分类号: G06F9/46 G06F17/30

    摘要: A method and apparatus for supplying data from a database to a group of transactions is provided. A value is maintained for the group of transactions. The value indicates a target snapshot of the database. When a transaction within the group of transactions accesses a data item, it is determined whether the transaction can use the target snapshot. If the transaction can use the target snapshot, then the transaction is supplied a version of the data item that belongs to the target snapshot. If the transaction cannot use the target snapshot, then the transaction is supplied a version of the data item other than the version of the data item that belongs to the target snapshot. Trying to supply data from the same snapshot to all of the transactions in the group increases the likelihood that the transactions will be able to use the same version of any given data item. Consequently, fewer reconstruction operations will have to be performed, and dynamic memory is less likely to become filled with different versions of the same data items.

    摘要翻译: 提供了一种从数据库向一组交易提供数据的方法和装置。 为该组交易维护一个值。 该值表示数据库的目标快照。 当事务组内的事务访问数据项时,确定事务是否可以使用目标快照。 如果事务可以使用目标快照,那么事务将被提供属于目标快照的数据项的版本。 如果事务不能使用目标快照,那么事务将被提供除了属于目标快照的数据项的版本之外的数据项的版本。 尝试将同一快照中的数据提供给组中的所有事务增加了事务将能够使用相同版本的任何给定数据项的可能性。 因此,必须执行更少的重建操作,并且动态内存不太可能充满相同数据项的不同版本。

    Dynamic snapshot set adjustment
    8.
    发明授权
    Dynamic snapshot set adjustment 失效
    动态快照集调整

    公开(公告)号:US5873098A

    公开(公告)日:1999-02-16

    申请号:US841541

    申请日:1997-04-23

    IPC分类号: G06F9/46 G06F17/30

    摘要: A method and apparatus for determining whether a particular version of a data item may be used by a transaction are provided. To determine whether the particular version may be used by the transaction, a MUST-SEE set associated with the transaction is compared to an EXCLUDED set associated with the particular version, and a CANNOT-SEE set associated with the transaction is compared to an INCLUDED set associated with the particular version. The MUST-SEE set includes all transactions that have made updates that must be seen by the transaction. The EXCLUDED set includes all transactions that have made updates to the data item that have been removed from the particular version of the data item and all transactions that will make changes to the data item in the future. The CANNOT-SEE set includes all transactions that have made updates that cannot be seen by the transaction. The INCLUDED set includes all transactions that have made updates that are reflected in the particular version of the data item. The particular version can be supplied to the transaction if no member of the MUST-SEE set is also a member of the EXCLUDED set, and no member of the CANNOT-SEE set is also a member of the INCLUDED set.

    摘要翻译: 提供了一种用于确定数据项的特定版本是否可被交易使用的方法和装置。 为了确定特定版本是否可以被事务使用,将与事务相关联的MUST-SEE集合与与特定版本相关联的EXCLUDED集合进行比较,并将与事务相关联的CAN NOT-SEE集合与INCLUDED集合进行比较 与特定版本相关联。 MUST-SEE集包括已经进行了交易必须看到的更新的所有交易。 EXCLUDED集包括对数据项进行更新的所有事务,该数据项已从数据项的特定版本中删除,并且将来会对数据项进行更改的所有事务。 CAN NOT-SEE集包括所有进行了事务无法看到的更新的事务。 INCLUDED集包括所有进行更新的事务,这些更新反映在数据项的特定版本中。 如果MUST-SEE集合的成员也不是EXCLUDED集合的成员,则该特定版本可以提供给事务,并且CAN NOT-SEE集合的任何成员也不是INCLUDED集合的成员。

    Communication architecture for distributed computing environment
    10.
    发明授权
    Communication architecture for distributed computing environment 有权
    分布式计算环境的通信架构

    公开(公告)号:US06920475B1

    公开(公告)日:2005-07-19

    申请号:US09298603

    申请日:1999-04-23

    摘要: 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.

    摘要翻译: 用于在分布式计算环境中执行工作的通信架构涉及在客户机节点上向客户端发送工作请求的客户端进程。 导演检查工作请求以确定执行工作所需的一个或多个资源以及可提供所需资源的一个或多个服务器节点。 导演然后将工作请求转发到可以提供所需资源的服务器节点上的服务器进程。 提供给服务器进程的工作请求指定将工作结果直接从服务器进程提供给进行工作请求的客户端进程。 导演维护一个资源数据表,指定由分布式计算环境中的服务器节点提供和/或可用的服务和/或资源。