Importance

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Abstract

A data system has a data server and multiple clients. The data server organizes data according to a tree index structure, where memory pages used to store data are indexed by higher level index nodes in the tree structure. The index nodes are replicated and maintained locally at the clients. The data organization on the server is further characterized by use of indexed side links between data pages to provide side access traversal, such as a Pi-tree structure. During a search for a particular search space, a requesting client traverses its own index replica until reference is made to a data page at the server. If the request causes a data page split or otherwise changes the storage location of a particular search space, the server sends information back as part of the result message to the requesting client to update the tree index replica. However, no coherence messages are sent to other clients. Instead, the other clients learn of data page splits and other changes to the search space in their own time when they request the search space. When a second client tries to access a search space that has changed due to activity of the first client, the second client is initially directed to the data page it expects to contain the search space. The server then side traverses the data pages using the indexed side links until the actual data page with the search space is located. Each side traversal results in its index term being included in the result message. Such index terms, when received at the index replica, are posted in the replica maintained at the second client to update that index replica. Accordingly, replicas are maintained as a by product of their individual search requests, thereby removing the need for coherence or other coordination messages among all index replicas.

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First Claim