waashk/acm huggingface dataset:
warehousing and mining web logs  analyzing web logs for usage and access trends can not only provide important information to web site developers and administrators, but also help in creating adaptive web sites. while there are many existing tools that generate fixed reports from web logs, they typically do not allow ad-hoc analysis queries. moreover, such tools cannot discover hidden patterns of access embedded in the access logs. we describe a relational olap (rolap) approach for creating a web-log warehouse. this is populated both from web logs, as well as the results of mining web logs. we also present a web based ad-hoc tool for analytic queries on the warehouse. we discuss the design criteria that influenced our choice of dimensions, facts and data granularity, and present the results from analyzing and mining the logs.  karuna p. joshi anupam joshi yelena yesha raghu krishnapuram
alternative techniques for the efficient acquisition of haptic data  immersive environments are those that surround users in an artificial world. these environments consist of a composition of various types of immersidata; unique data types that are combined to render a virtual experience. acquisition, for storage and future querying, of information describing sessions in these environments is challenging because of the real- time demands and sizeable amounts of data to be managed. in this paper, we summarize a comparison of techniques for achieving the efficient acquisition of one type of immersidata, the haptic data type, which describes the movement, rotation, and force associated with user-directed objects in an immersive environment. in addition to describing a general process for real- time sampling and recording of this type of data, we propose three distinct sampling strategies: fixed, grouped, and adaptive. we conducted several experiments with a real haptic device and found that there are tradeoffs between the accuracy, efficiency, and complexity of implementation for each of the proposed techniques. while it is possible to use any of these approaches for real-time haptic data acquisition, we found that an adaptive sampling strategy provided the most efficiency without significant loss in accuracy. as immersive environments become more complex and contain more haptic sensors, techniques such as adaptive sampling can be useful for improving scalability of real-time data acquisition.  cyrus shahabi mohammad r. kolahdouzan greg barish roger zimmermann didi yao kun fu lingling zhang
an adaptive view element framework for multi-dimensional data management  we present an adaptive wavelet view element framework for managing different types of multi-dimensional data in storage and retrieval applications. we consider the problems of multi-dimensional data compression, multi-resolution subregion access, selective materialization, progressive retrieval and similarity searching. the framework uses wavelets to partition the multi- dimensional data into view elements that form the building blocks for synthesizing views of the data. the view elements are organized and managed using different view element graphs. the graphs are used to guide cost-based view element selection algorithms for optimizing compression, access, retrieval and search performance.  we present the adaptive wavelet view element framework and describe its application in managing multi-dimensional data such as 1-d time series data, 2-d images, video sequences, and multi-dimensional data cubes. we present experimental results that demonstrate that the adaptive wavelet view element framework improves performance of compressing, accessing, and retrieving multi- dimensional data compared to non-adaptive methods.  john r. smith chung-sheng li
a fault-tolerant commit protocol for replicated databases  when failures occur during the execution of distributed commit protocols, the protocols may block in some partitions to avoid inconsistent termination of the transaction, thus making data items in these partitions unavailable for accesses. we present a protocol that incorporates two new ideas with the goal of improving data availability. first, a new two-level voting scheme is proposed for deciding in which partitions to terminate the transaction. in this scheme, a choice is made based on the number of data items available in the partition rather than on the number of individual nodes. indeed, in replicated systems, a criterion based on the number of nodes may be misleading. second, we propose a way to reduce blocking caused by accumulating network fragmentation. the idea employs the views mechanism previously used in replica management.  michael rabinovich edward d. lazowska
equality and domain closure in first-order databases  a class of first-order databases with no function signs is considered. a closed database db is one for which the only existing individuals are those explicitly referred to in the formulas of db. formally, this is expressed by including in db a domain closure axiom (x)x = c1 ∨***∨ x = cp, where c1,…,cp are all of the constants occurring in db. it is shown how to completely capture the effects of this axiom by means of suitable generalizations of the projection and division operators of relational algebra, thereby permitting the underlying theorem prover used for query evaluation to ignore this axiom.  a database is e-saturated if all of its constants denote distinct individuals. it is shown that such databases circumvent the usual problems associated with equality, which arise in more general databases.  finally, it is proved for horn databases and positive queries that only definite answers are obtained, and for databases with infinitely many constants that infinitely long indefinite answers can arise.  raymond reiter
a language facility for designing database-intensive applications  taxis, a language for the design of interactive information systems (e.g., credit card verification, student-course registration, and airline reservations) is described. taxis offers (relational) database management facilities, a means of specifying semantic integrity constraints, and an exception-handling mechanism, integrated into a single language through the concepts of class, property, and the is-a (generalization) relationship. a description of the main constructs of taxis is included and their usefulness illustrated with examples.  john mylopoulos philip a. bernstein harry k. t. wong
direct: a query facility for multiple databases  the subject of this research project is the architecture and design of a multidatabase query facility. these databases contain structured data, typical for business applications. problems addressed are: presenting a uniform interface for retrieving data from multiple databases, providing autonomy for the component databases, and defining an architecture for semantic services.  direct is a query facility for heterogeneous databases. the databases and their definitions can differ in their data models, names, types, and encoded values. instead of creating a global schema, descriptions of different databases are allowed to coexist. a multidatabase query language provides a uniform interface for retrieving data from different databases. direct has been exercised with operational databases that are part of an automated business system.  ulla merz roger king
on balancing the load in a clustered web farm in this article we propose a novel, yet practical, scheme which attempts to optimally balance the load on the servers of a clustered web farm. the goal in solving this performance problem is to achieve minimal average response time for customer requests, and thus ultimately achieve maximal customer throughput. the article decouples the overall problem into two related but distinct mathematical subproblems, one static and one dynamic. we believe this natural decoupling is one of the major contributions of our article. the _static_ component algorithm determines good assignments of sites to potentially overlapping servers. these cluster assignments, which, due to overhead, cannot be changed too frequently, have a major effect on achievable response time. additionally, these assignments must be palatable to the sites themselves. the _dynamic_ component algorithm is designed to handle real-time load balancing by routing customer requests from the network dispatcher to the servers. this algorithm must react to fluctuating customer request load while respecting the assignments of sites to servers determined by the static component. the static and dynamic components both employ in various contexts the same so-called _goal setting_ algorithm. this algorithm determines the theoretically optimal load on each server, given hypothetical cluster assignments and site activity. we demonstrate the effectiveness of the overall load-balancing scheme via a number of simulation experiments. joel l. wolf philip s. yu
designing storytelling technologies to encouraging collaboration between youngchildrenwe describe the iterative design of two collaborative storytellingtechnologies for young children, kidpad and the klump. we focus on the idea ofdesigning interfaces to subtly encourage collaboration so that children areinvited to discover the added benefits of working together. this idea has beenmotivated by our experiences of using early versions of our technologies inschools in sweden and the uk. we compare the approach of encouragingcollaboration with other approaches to synchronizing shared interfaces. wedescribe how we have revised the technologies to encourage collaboration andto reflect design suggestions made by the children themselves.steve benford benjamin b. bederson karl-petter Ã...kesson victor bayon allisondruin pÃ¤r hansson juan pablo hourcade rob ingram helen neale claire o'malleykristian t. simsarian danaÃ" stanton yngve sundblad gustav taxen
a transitive closure and magic functions machine  an extended version of our simd relational algebraic processor is presented. in addition to the usual relational and set operations the new machine has the ability to recycle its responder sets internally. this allows it to perform repeated joins, for example, without external intervention and so achieve operations such as path discovery and transitive closure in graphs stored as relations, and to evaluate various types of recursive query. the many compiled methods for recursive query evaluation are applicable in this system as in any other relational database, and can be efficiently evaluated because of the in- built recursive and iterative capability of our machine. the magic functions approach has a clear connection with the machine since it uses relations as magic functions.  jerome robinson simon lavington
intelligent caching: selecting, representing, and reusing data in an information server  accessing information sources to retrieve data requested by a user can be expensive, especially when dealing with distributed information sources. one way to reduce this cost is to cache the results of queries, or related classes of data. this paper presents an approach to caching and addresses the issues of which information to cache, how to describe what has been cached, and how to use the cached information to answer future queries. we consider these issues in the context of the sims information server, which is a system for retrieving information from multiple heterogeneous and distributed information sources. the design of this information server is ideal for representing and reusing cached information since each class of cached information is simply viewed as another information source that is available for answering future queries.  yigal arens craig a. knoblock
database selection for processing k nearest neighbors queries in distributed environments  we consider the processing of digital library queries, consisting of a text component and a structured component in distributed environments. the text component can be processed using techniques given in previous papers such as [7, 8, 11]. in this paper, we concentrate on the processing of the structured component of a distributed query. histograms are constructed and algorithms are given to provide estimates of the desirabilities of the databases with respect to the given query. databases are selected in descending order of desirability. an algorithm is also given to select tuples from the selected databases. experimental results are given to show that the techniques provided here are effective and efficient.  clement yu prasoon sharma weiyi meng yan qin
the perceptual structure of multidimensional input device selection  concepts such as the logical device, taxonomies, and other descriptive frameworks have improved understanding of input devices but ignored or else treated informally their pragmatic qualities, which are fundamental to selection of input devices for tasks. we seek the greater leverage of a predictive theoretical framework by basing our investigation of three- dimensional vs. two-dimensional input devices on garner's theory of processing of perceptual structure in multidimensional tasks. two three- dimensional tasks may seem equivalent, but if they involve different types of perceptual spaces, they should be assigned correspondingly different input devices. our experiment supports this hypothesis and thus both indicates when to use three- dimensional input devices and gives credence to our theoretical basis for this indication.  robert j. k. jacob linda e. sibert
formal aspects of concurrency control in long-duration transaction systems using the nt/pv model  in the typical database system, an execution is correct if it is equivalent to some serial execution. this criterion, called serializability, is unacceptable for new database applications which require long-duration transactions. we present a new transaction model which allows correctness criteria more suitable for these applications. this model combines three enhancements to the standard model: nested transactions, explicit predicates, and multiple versions. these features yield the name of the new model, nested transactions with predicates and versions, or nt/pv.  the modular nature of the nt/pv model allows a straightforward representation of simple systems. it also provides a formal framework for describing complex interactions. the most complex interactions the model allows can be captured by a protocol which exploits all of the semantics available to the nt/pv model. an example of these interactions is shown in a case application. the example shows how a system based on the nt/pv model is superior to both standard database techniques and unrestricted systems in both correctness and performance.  henry f. korth greg speegle
specification of content-dependent security policies  the protection of information from unauthorized disclosure is an important consideration for the designers of any large multiuser computer system. a general purpose database management system often requires the enforcement of content-dependent security policies in which a decision to allow access must be based on the value of the data itself. several authors ([har76], [sto76], [gri76], [sum77], [min78], [spo83], and others) have proposed mechanisms for implementing content-dependent security policies. few authors, however, have investigated the properties of models for the specification of such policies.  this paper identifies several problems created by inadequate models for the specification of content-dependent security policies. if a specification model is too liberal in the types of policies it can express, it may provide an increased opportunity for compromise of data. if the specification model is too conservative, it cannot express many desirable policies. thus a flexible model which will allow a compromise between these two extremes is needed for specifying content-dependent policies. such a model is proposed here.  david l. spooner
hyperform: a hypermedia system development environment  development of hypermedia systems is a complex matter. the current trend toward open, extensible, and distributed multiuser hypermedia systems adds additional complexity to the development process. as a means of reducing this complexity, there has been an increasing interest in hyperbase management systems that allow hypermedia system developers to abstract from the intricacies and complexity of the hyperbase layer and fully attend to application and user interface issues. design, development, and deployment experiences of a dynamic, open, and distributed multiuser hypermedia system development environment called hyperform is presented. hyperform is based on the concepts of extensibility, tailorability, and rapid prototyping of hypermedia system services. open, extensible hyperbase management systems permit hypermedia system developers to tailor hypermedia functionality for specific applications and to serve as a platform for research. the hyperform development environment is comprised of multiple instances of four component types: (1) a hyperbase management system server, (2) a tool integrator, (3) editors, and (4) participating tools. hyperform has been deployed in unix environments, and experiments have shown that hyperform greatly reduces the effort required to provide customized hyperbase management system support for distributed multiuser hypermedia systems.  uffe k. wiil john j. leggett
evolution and change in data management - issues and directions  one of the fundamental aspects of information and database systems is that they change. moreover, in so doing they evolve, although the manner and quality of this evolution is highly dependent on the mechanisms in place to handle it. while changes in data are handled well, changes in other aspects, such as structure, rules, constraints, the model, etc., are handled to varying levels of sophistication and completeness.  in order to study this in more detail a workshop on evolution and change in data management was held in paris in november 1999. it brought together researchers from a wide range of disciplines with a common interest in handling the fundamental characteristics and the conceptual modelling of change in information and database systems. this short report of the workshop concentrates on some of the general lessons that emerged during the four days.  john f. roddick lina al-jadir leopoldo bertossi marlon dumas florida estrella heidi gregersen kathleen hornsby jens lufter federica mandreoli tomi männistö enric mayol lex wedemeijer
efficient computation of temporal aggregates with range predicates  a temporal aggregation query is an important but costly operation for applications that maintain time-evolving data (data warehouses, temporal databases, etc.). due to the large volume of such data, performance improvements for temporal aggregation queries are critical. in this paper we examine techniques to compute temporal aggregates that include key-range predicates (_range temporal aggregates_). in particular we concentrate on sum, count and avg aggregates. this problem is novel; to handle arbitrary key ranges, previous methods would need to keep a separate index for every possible key range. we propose an approach based on a new index structure called the _multiversion sb-tree_, which incorporates features from both the sb-tree and the multiversion b-tree, to handle arbitrary key-range temporal sum, count and avg queries. we analyze the performance of our approach and present experimental results that show its efficiency.  donhui zhang alexander markowetz vassilis tsotras dimitrios gunopulos bernhard seeger
an outline of a general model for information retrieval systems  this paper is a contribution to the construction of a general model for information retrieval. as in the paper of van rijsbergen ([rij86]), the implicit base in all information retrieval systems is considered as a logical implication. the measure of correspondence between a document and a query is transformed into the estimation of the strength (or certainty) of logical implication. the modal logics will show its suitability for representing the behavior of information retrieval systems. in existing information retrieval models, several aspects are often mixed. a part of this paper is contributed to separate these aspects to give a clearer view of information retrieval systems. this general model is also compared with some existing models to show its generality.  j. nie
a foundation for representing and querying moving objects  spatio- temporal databases deal with geometries changing over time. the goal of our work is to provide a dbms data model and query language capable of handling such time-dependent geometries, including those changing continuously that describe moving objects. two fundamental abstractions are moving point and moving region, describing objects for which only the time-dependent position, or position and extent, respectively, are of interest. we propose to present such time-dependent geometries as attribute data types with suitable operations, that is, to provide an abstract data type extension to a dbms data model and query language. this paper presents a design of such a system of abstract data types. it turns out that besides the main types of interest, moving point and moving region, a relatively large number of auxiliary data types are needed. for example, one needs a line type to represent the projection of a moving point into the plane, or a "moving real" to represent the time-dependent distance of two points. it then becomes crucial to achieve (i) orthogonality in the design of the system, i.e., type constructors can be applied unifomly; (ii) genericity and consistency of operations, i.e., operations range over as many types as possible and behave consistently; and (iii) closure and consistency between structure and operations of nontemporal and related temporal types. satisfying these goal leads to a simple and expressive system of abstract data types that may be integrated into a query language to yield a powerful language for querying spatio-temporal data, including moving objects. the paper formally defines the types and operations, offers detailed insight into the considerations that went into the design, and exemplifies the use of the abstract data types using sql. the paper offers a precise and conceptually clean foundation for implementing a spatio-temporal dbms extension.  ralf hartmut guting michael h. böhlen martin erwig christian s. jensen nikos a. lorentzos markus schneider michalis vazirgiannis
an effective algorithm for parallelizing sort merge joins in the presence of data skew  parallel processing of relational queries has received considerable attention of late. however, in the presence of data skew, the speedup from conventional parallel join algorithms can be very limited, due to load imbalances among the various processors. even a single large skew element can cause a processor to become overloaded. in this paper, we propose a parallel sort merge join algorithm which uses a divide-and-conquer approach to address the data skew problem. the proposed algorithm adds an extra scheduling phase to the usual sort, transfer and join phases. during the scheduling phase, a parallelizable optimization algorithm, using the output of the sort phase, attempts to balance the load across the multiple processors in the subsequent join phase. the algorithm naturally identifies the largest skew elements, and assigns each of them to an optimal number of processors. assuming a zipf-like distribution for data skew, the algorithm is demonstrated to achieve very good load balancing for the join phase in a cpu-bound environment, and is shown to be very robust relative to the degree of data skew and the total number of processors.  joel l. wolf daniel m. dias philip s. yu