| 摘要 |
A distributed database system includes a central data server, and a plurality of application nodes for receiving connections from clients. Each application node is in communication with the central data server, and has a data cache which maintains local copies of recently used data items. The central data server keeps track of which data items are stored in each data cache and makes callback requests to the data caches to request the return of data items that are needed elsewhere. Data items, including modified data items, are cached locally at a local application node so long as the locally cached data items are only being accessed by the local application node. The local application node handles transactions and stores changes to the data items. The local application node forwards changes, in order by transaction, to the central data server to insure consistency, thereby providing limited durability write caching.
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