摘要:
A distributed object is hosted in a distributed system by invoking a global hash function on a generated name for the distributed object. The name for the distributed object is generated with knowledge of the global hash function so that the result of invoking the global hash function upon the name results in the selection of a predetermined node in the distributed system. The predetermined node may be selected based on the affinity of the node to the distributed object for reducing network messaging and communications overhead.
摘要:
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.
摘要:
A method and an apparatus for managing access to data on a distributed database system is provided. A snapshot list is generated for a transaction executing on the distributed database system. The snapshot list specifies snapshot times for a plurality of locations in the distributed database system. The snapshot times are determined based upon the location of a data item and the location where the transaction is executing. The selection of a version of the data item to be provided to the transaction is made based upon the snapshot time for the location associated with the data.
摘要:
A method for preventing multiple pings. An embodiment of the invention detects requests of data blocks entailing pings likely to cause additional pings. The servicing of requests involving a pings likely to cause additional pings is deferred until a service enabling conditions occurs. Another embodiment of the invention detects situations where by further updating a data block before pinging the data block use of resources on the remote node requesting the data block are reduced. The servicing of the request for the data block is deferred until a service enabling conditions occurs.
摘要:
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.
摘要:
A method for updating and reading data stored in a static memory in a computer system is disclosed. An update queue stores one or more update records in dynamic memory that specify changes made by a transaction to data stored in the static memory. If a transaction requests data for which the transaction has previously generated an update record updated data is generated in dynamic memory, where the updated data reflecting the changes specified by the update records. The updated data is then supplied to the transaction.
摘要:
A method and apparatus for supplying a particular version of a data item to a transaction executing in a first database server is provided. The data item is in a database accessible by the first database server and one or more other database servers. The method involves determining whether a current version of the data item resides in a cache that is remote relative to the first database server. If the current version of the data item does not reside in a cache that is remote relative to the first database server, then a first derivation mechanism that is local to the first database server to derives the particular version of the data item from the current version of the data item. If the current version of the data item resides in a cache that is remote relative to the first database server, then a second derivation mechanism that is local to the cache derives the particular version of the data item from the current version of the data item. Once built, the particular version of the data item sent to the first database server. Determining whether a current version of the data item resides in a cache that is remote relative to the first database server may be performed by determining whether a process currently holds a write lock on the data item, and if a process currently holds a write lock on the data item, then determining whether the process is remote relative to the first database server.
摘要:
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.
摘要:
A method and apparatus for dynamic lock granularity escalation and de-escalation in a computer system is provided. Upon receiving a request for a resource, a scope of a previously granted lock is modified. According to one embodiment, hash lock de-escalation is employed. In hash lock de-escalation, the scope of the previously granted lock held on a set of resources is reduced by de-escalating the previously granted lock from a coarser-grain lock to one or more finer-grain locks on members of the set. According to another embodiment, hash lock escalation is employed. In hash lock escalation, the scope of previously granted locks held on one or more members of the set of resources are released and promoted into a coarser-grain lock that covers the set of resources as well as the requested resource.
摘要:
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.