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Ordered labeled trees are trees in which the left-to-right order among siblings is. significant. The distance between two ordered trees is considered to be the weighted number of edit operations (insert, delete, and modify) to transform one tree to another. The problem of approximate tree matching is also considered. Specifically, algorithms are designed to(More)
Update anywhere-anytime-anyway transactional replication has unstable behavior as the workload scales up: a ten-fold increase in nodes and traffic gives a thousand fold increase in deadlocks or reconciliations. Master copy replication (primary copy) schemes reduce this problem. A simple analytic model demonstrates these results. A new two-tier replication(More)
We have implemented a secure network file system called SUNDR that guarantees the integrity of data even when malicious parties control the server. SUNDR splits storage functionality between two untrusted components, a block store and a consistency server. The block store holds all file data and most metadata. Without interpreting metadata, it presents a(More)
In this paper we consider an optimization problem that arises in the execution of parallel programs on shared-memory multiple-instruction-stream, multiple-data-stream (MIMD) computers. A program on such machines consists of many sequential program segments, each executed by a single processor. These segments interact as they access shared variables. Access(More)
ABSTRACT Publish/Subs ribe is the paradigm in whi h users express long-term interests (\subs riptions") and some agent \publishes" events (e.g., o ers). The job of Publish/Subs ribe software is to send events to the owners of subs riptions satis ed by those events. For example, a user subs ription may onsist of an interest in an airplane of a ertain type,(More)
Consider the problem of monitoring tens of thousands of time series data streams in an online fashion and making decisions based on them. In addition to single stream statistics such as average and standard deviation, we also want to nd high correlations among all pairs of streams. A stock market trader might use such a tool to spot arbitrage opportunities.(More)
In a path-breaking paper last year Pat and Betty O'Neil and Gerhard Weikum proposed a self-tuning improvement to the Least Recently Used (LRU) buuer management algorithmm15]. Their improvement is called LRU/k and advocates giving priority to buuer pages based on the kth most recent access. (The standard LRU algorithm is denoted LRU/1 according to this(More)
In applications ranging from video reception to telecommunications and packet communication to aircraft control, tasks enter periodically and have xed response time constraints, but missing a deadline is acceptable, provided most deadlines are met. We call such tasks \occasionally skippable". We look at the problem of uniprocessor scheduling of occasionally(More)
Snapshot Isolation (SI) is a multiversion concurrency control algorithm, first described in Berenson et al. [1995]. SI is attractive because it provides an isolation level that avoids many of the common concurrency anomalies, and has been implemented by Oracle and Microsoft SQL Server (with certain minor variations). SI does not guarantee serializability in(More)
Modern search engines answer keyword-based queries extremely efficiently. The impressive speed is due to clever inverted index structures, caching, a domain-independent knowledge of strings, and thousands of machines. Several research efforts have attempted to generalize keyword search to keytree and keygraph searching, because trees and graphs have many(More)