waashk/acm huggingface dataset:
dynamic frame rate control for video streams  a mechanism for dynamically varying the frame rate of pre-encoded video clips is described. an off-line encoder creates a high quality bitstream encoded at 30 fps, as well as separate files containing motion vectors for the same clip at lower frame rates. an on-line encoder decodes the bitstream (if necessary) and re-encodes it at lower frame-rates in real-time using the pre-computed, stored motion information. dynamic frame rate control, used in conjunction with dynamic bit- rate control, allows clients to solve the rate mismatch between the bandwidth available to them and the bit-rate of the pre-encoded bitsream. it also provides a means for implementing fast forward control for video streaming without increasing bandwidth consumption.  sassan pejhan ti-hao chiang ya-qin zhang
database-friendly random projections  a classic result of johnson and lindenstrauss asserts that any set of _n_ points in _d_-dimensional euclidean space can be embedded into _k_-dimensional euclidean space where _k_ is logarithmic in _n_ and independent of _d_ so that all pairwise distances are maintained within an arbitrarily small factor. all known constructions of such embeddings involve projecting the _n_ points onto a random _k_-dimensional hyperplane. we give a novel construction of the embedding, suitable for database applications, which amounts to computing a simple aggregate over _k_ random attribute partitions.  dimitris achlioptas
liveboard: a large interactive display supporting group meetings, presentations, and remote collaboration  this paper describes the liveboard, a large interactive display system. with nearly one million pixels and an accurate, multi-state, cordless pen, the liveboard provides a basis for research on user interfaces for group meetings, presentations and remote collaboration. we describe the underlying hardware and software of the liveboard, along with several software applications that have been developed. in describing the system, we point out the design rationale that was used to make various choices. we present the results of an informal survey of liveboard users, and describe some of the improvements that have been made in response to user feedback. we conclude with several general observations about the use of large public interactive displays.  scott elrod richard bruce rich gold david goldberg frank halasz william janssen david lee kim mccall elin pedersen ken pier john tang brent welch
options in physical database design  a cornerstone of modern database systems is physical data independence, i.e., the separation of a type and its associated operations from its physical representation in memory and on storage media. users manipulate and query data at the logical level; the dbms translates these logical operations to operations on files, indices, records, and disks. the efficiency of these physical operations depends very much on the choice of data representations.  choosing a physical representation for a logical database is called physical database design. the number of possible choices in physical database design is very large; moreover, they very often interact with each other. we attempt to list and classify these choices and to explore their interactions. the purpose of this paper is to provide an overview of possible options to the dbms developer and some guidance to the dbms administrator and user.  while much of our discussion will draw on the relational data model, physical database design is of even more importance for object-oriented and extensible systems. the reasons are simple: first, the number of logical data types and their operations is larger, requiring and permitting more choices for their representation. second, the state of the art in query optimization for these systems is much less developed than for relational systems, making careful physical database design even more imperative for object-oriented database systems.  goetz graefe
database model for web-based cooperative applications  in this paper we propose a model of a database that could become a kernel of cooperative database applications. first, we propose a new data model cdm (collaborative data model) that is oriented for the specificity of multiuser environments, in particular: cooperation scenarios, cooperation techniques and cooperation management. second, we propose to apply to databases supporting collaboration so called multiuser transactions. multiuser transactions are flat transactions in which, in comparison to classical acid transactions, the isolation property is relaxed.  waldemar wieczerzycki
efficient and flexible methods for transient versioning of records to avoid locking by read-only transactions  we present efficient and flexible methods which permit read-only transactions that do not mind reading a possibly slightly old, but still consistent, version of the data base to execute without acquiring locks. this approach avoids the undesirable interferences between such queries and the typically shorter update transactions that cause unnecessary and costly delays. indexed access by such queries is also supported, unlike by the earlier methods. old versions of records are maintained only in a transient fashion. our methods are characterized by their flexibility (number of versions maintained and the timing of version switches, supporting partial rollbacks, and different recovery and buffering methods) and their efficiency (logging, garbage collection, version selection, and incremental, record-level versioning). distributed data base environments are also supported, including commit protocols with the read-only optimization. we also describe efficient methods for garbage collecting unneeded older versions.  c. mohan hamid pirahesh raymond lorie
fast-start: quick fault recovery in oracle  availability requirements for database systems are more stringent than ever before with the widespread use of databases as the foundation for ebusiness. this paper highlights _fast-start_ _fault recovery_, an important availability feature in oracle, designed to expedite recovery from unplanned outages. fast- start allows the administrator to configure a running system to impose predictable bounds on the time required for crash recovery. for instance, fast-start allows fine-grained control over the duration of the roll-forward phase of crash recovery by adaptively varying the rate of checkpointing with minimal impact on online performance. persistent transaction locking in oracle allows normal online processing to be resumed while the rollback phase of recovery is still in progress, and fast-start allows quick and transparent rollback of changes made by uncommitted transactions prior to a crash.  tirthankar lahiri amit ganesh ron weiss ashok joshi
a transaction-based approach to relational database specification  an operational approach to database specification is proposed and investigated. valid database states are described as the states resulting from the application of admissible transactions, specified by a transactional schema. the approach is similar in spirit to the modeling of behavior by methods and encapsulation in object- oriented systems. the transactions considered are line programs consisting of insertions, deletions, and modifications, using simple selection conditions. the results concern basic properties of transactional schemas, as well as the connection with traditional constraint schemas. in particular, the expressive power of transactional schemas is characterized. although it is shown that transaction- based specification and constraint-based specification are incomparable, constraints of practical interest that have corresponding transactional schemas are identified. the preservation of constraints by transactions is also studied.  serge abiteboul victor vianu
retrieval performance versus disc space utilization on worm optical discs  steady progress in the development of optical disc technology over the past decade has brought it to the point where it is beginning to compete directly with magnetic disc technology. worm optical discs in particular, which permanently register information on the disc surface, have significant advantages over magnetic technology for applications that are mainly archival in nature but require the ability to do frequent on-line insertions.  in this paper, we propose a class of access methods that use rewritable storage for the temporary buffering of insertions to data sets stored on worm optical discs and we examine the relationship between the retrieval performance from worm optical discs and the utilization of disc storage space when one of these organizations is employed. we describe the performance trade off as one of fast sequential retrieval of the contents of a block versus wasted space owing to data replication. a model of a specific instance of such an organization (a buffered hash file scheme) is described that allows for the specification of retrieval performance objectives. alternative strategies for managing data replication that allow trade offs between higher consumption rates and better average retrieval performance are also described. we then provide an expected value analysis of the amount of disc space that must be consumed on a worm disc to meet specified performance limits. the analysis is general enough to allow easy extension to other types of buffered files systems for worm optical discs.  stavros christodoulakis daniel alexander ford
sagas  long lived transactions (llts) hold on to database resources for relatively long periods of time, significantly delaying the termination of shorter and more common transactions. to alleviate these problems we propose the notion of a saga. a llt is a saga if it can be written as a sequence of transactions that can be interleaved with other transactions. the database management system guarantees that either all the transactions in a saga are successfully completed or compensating transactions are run to amend a partial execution. both the concept of saga and its implementation are relatively simple, but they have the potential to improve performance significantly. we analyze the various implementation issues related to sagas, including how they can be run on an existing system that does not directly support them. we also discuss techniques for database and llt design that make it feasible to break up llts into sagas.  hector garcia-molina kenneth salem
the distributed information search component (disco) and the world wide web  the distributed information search component (disco) is a prototype heterogeneous distributed database that accesses underlying data sources. the disco prototype currently focuses on three central research problems in the context of these systems. first, since the capabilities of each data source is different, transforming queries into subqueries on data source is difficult. we call this problem the weak data source problem. second, since each data source performs operations in a generally unique way, the cost for performing an operation may vary radically from one wrapper to another. we call this problem the radical cost problem. finally, existing systems behave rudely when attempting to access an unavailable data source. we call this problem the ungraceful failure problem.  disco copes with these problems. for the weak data source problem, the database implementor defines precisely the capabilities of each data source. for the radical cost problem, the database implementor (optionally) defines cost information for some of the operations of a data source. the mediator uses this cost information to improve its cost model. to deal with ungraceful failures, queries return partial answers. a partial answer contains the part of the final answer to the query that was produced by the available data sources. the current working prototype of disco contains implementations of these solutions and operations over a collection of wrappers that access information both in files and on the world wide web.  anthony tomasic remy amouroux philippe bonnet olga kapitskaia hubert naacke louiqa raschid
corr: a computing research repository  this paper describes the decisions by which teh association for computing machinery integrated good features from the los alamos e-print (physics) archive and from cornell university's networked computer science technical reference library to form their own open, permanent, online "computing research repository" (corr). submitted papers are not refereed and anyone can browse and extract corr material for free, so corr's eventual success could revolutionize computer science publishing. but several serious challenges remain: some journals forbid online preprints, teh corr user interface is cumbersome, submissions are only self-indexed, (no professional library staff manages teh archive) and long-term funding is uncertain.  joseph y. halpern
representation in virtual space: visual convention in the graphical user interface  the graphical user interface (gui) typically provides a multi-windowed environment within a flat workspace or "desktop." simultaneously, however, controls for executing commands within this interface are increasingly being rendered three- dimensionally. this paper explores ways in which the space of the gui desktop might be literally and figuratively deepened through the incorporation of visual devices that have emerged during the history of art--- specifically, perspective and light effects. by enriching the visual vocabulary of the gui, greater semantic complexity becomes sustainable.  loretta staples
symmetric bimanual interaction  we present experimental work that explores the factors governing symmetric bimanual interaction in a two-handed task that requires the user to track a pair of targets, one target with each hand. a symmetric bimanual task is a two-handed task in which each hand is assigned an identical role. in this context, we explore three main experimental factors. we vary the _distance_ between the pair of targets to track: as the targets become further apart, visual diversion increases, forcing the user to divide attention between the two targets. we also vary the demands of the task by using both a slow and a fast _tracking speed_. finally, we explore _visual integration_ of sub-tasks: in one condition, the two targets to track are connected by a line segment which visually links the targets, while in the other condition there is no connecting line. our results indicate that all three experimental factors affect the degree of parallelism, which we quantify using a new metric of bimanual parallelism. however, differences in tracking error between the two hands are affected only by the visual integration factor.  ravin balakrishnan ken hinckley
a suitable relational model for temporal databases (abstract only)  the relational approach has been applied very literally to temporal databases. for example, the salary and dept of an employee do not necessarily change at the same time, resulting in a split of information into two tables: name salary start end and name dept start end, where start and end are instants of time, treated as special attributes. a unit of information, such as salary of an employee, is further split into several tuples. normal forms, dependencies and other nice concepts of relational databases remain inapplicable to the temporal case. we propose that a tuple, the fundamental molecular unit of information, be viewed as a function from a union of finitely many intervals of time into domains of attributes. this eliminates the problems stated above. it gives rise to elegant relational algebra, tuple calculus and other query languages and brings temporal databases within the classical framework. it is hoped that this model will draw the attention of researchers to temporal databases.  shashi gadia
instrumental interaction: an interaction model for designing post-wimp user interfaces  this article introduces a new interaction model called instrumental interaction that extends and generalizes the principles of direct manipulation. it covers existing interaction styles, including traditional wimp interfaces, as well as new interaction styles such as two-handed input and augmented reality. it defines a design space for new interaction techniques and a set of properties for comparing them. instrumental interaction describes graphical user interfaces in terms of _domain objects_ and _interaction instruments_. interaction between users and domain objects is mediated by interaction instruments, similar to the tools and instruments we use in the real world to interact with physical objects. the article presents the model, applies it to describe and compare a number of interaction techniques, and shows how it was used to create a new interface for searching and replacing text.  michel beaudouin-lafon
optimum probability estimation based on expectations  probability estimation is important for the application of probabilistic models as well as for any evaluation in ir. we discuss the interdependencies between parameter estimation and other properties of probabilistic models. then we define an optimum estimate which can be applied to various typical estimation problems in ir. a method for the computation of this estimate is described which uses expectations from empirical distributions. some experiments show the applicability of our method, whereas comparable approaches are partially based on false assumptions or yield estimates with systematic errors.  n. fuhr h. huther
a comparison of relational database management systems unify and idb  one of the most important qualities of a database management system running on a small system is its ability to provide data independence. a relational database management system provides data independence through its use of tables for data storage. use of a standard operating system means that a database management system can be run on a wide variety of systems, allowing data to be transported not only between small systems but between small and large systems.  assuming that a database management system provides data independence, what other features are needed? a comparison of the features provided by two such database management systems and how easy they are to use would be helpful in answering this question. this paper presents a comparison of unify and intel database management system (idb). both are relational, multi-user systems that run under the unix operating system.  lindsay mcdermid
human-computer interaction research at georgia institute of technology  hci research at georgia tech is found in three cooperating groups: the engineering psychology and experimental psychology programs in the school of psychology, the center for human-machine systems research in the school of industrial and systems engineering, and the interdisciplinary graphics, visualization and usability (gvu) center. we cooperate via cross-listed courses, having students in one area take a minor in another area, collaborative research projects, serving on ph. d. committees, joint colloquia and brown bag lunches, and joint appointments. the gvu center (housed in the college of computing) and cognitive science program (sponsored by psychology, industrial and systems engineering, and the college of computing) involves a number of the same faculty, further enhancing our collaborations.  james d. foley christine m. mitchell neff walker
crash recovery in client-server exodus  in this paper, we address the correctness and performance issues that arise when implementing logging and crash recovery in a page-server environment. the issues result from two characteristics of page-server systems: 1) the fact that data is modified and cached in client database buffers that are not accessible by the server, and 2) the performance and cost trade-offs that are inherent in a client-server environment. we describe a recovery system that we have implemented for the client-server version of the exodus storage manager. the implementation supports efficient buffer management policies, allows flexibility in the interaction between clients and the server, and reduces the server load by generating log records at clients. we also present a preliminary performance analysis of the implementation.  michael j. franklin michael j. zwilling c. k. tan michael j. carey david j. dewitt
`prabha' - a distributed concurrency control algorithm  we propose a non-preemptive, deadlock free concurrency control mechanism for distributed database systems. the algorithm uses a combination of transaction blocking and roll-back to achieve serialization. unlike other locking mechanisms presented in the past, the algorithm proposed here uses dynamic attributes of transactions to resolve conflicts to achieve serialization. we argue that using the dynamic attributes of transactions economizes memory use and reduces conflict resolution time.  albert burger vijay kumar
multigranularity locking in multiple job classes transaction processing system  the conditions of when to apply fine and coarse granularity to different kinds of transaction are well understood. however, it is not very clear how multiple job classes using different lock granularities affect each other. this study aims at exploring the impact of multigranularity locking on the performance of multiple job classes transaction processing system which is common in multiuser database system. there are two key findings in the study. firstly, lock granularity adopted by identical job classes should not differ from each other by a factor of more than 20; otherwise, serious data contention may result. secondly, short job class transactions are generally benefited when its level of granularity is similar to that of the long job class since this will reduce the additional lock overhead and data contention which are induced by multigranularity locking.  shan-hoi ng sheung- lun hung
a temporally oriented data model  the research into time and data models has so far focused on the identification of extensions to the classical relational model that would provide it with "adequate" semantic capacity to deal with time. the temporally oriented data model (todm) presented in this paper is a result of a different approach, namely, it directly operationalizes the pervasive three-dimensional metaphor for time. one of the main results is thus the development of the notion of the data cube: a three-dimensional and inherently temporal data construct where time, objects, and attributes are the primary dimensions of stored data. todm's cube adds historical depth to the tabular notions of data and provides a framework for storing and retrieving data within their temporal context. the basic operations in the model allow the formation of new cubic views from existing ones, or viewing data as one moves up and down in time within cubes.  this paper introduces todm, a consistent set of temporally oriented data constructs, operations, and constraints, and then presents tosql, a corresponding end-user's sql-like query syntax. the model is a restricted but consistent superset of the relational model, and the query syntax incorporates temporal notions in a manner that likewise avoids penalizing users who are interested solely in the current view of data (rather than in a temporal perspective). the naturalness of the spatial reference to time and the added semantic capacity of todm come with a price---the definitions of the cubic constructs and basic operations are relatively cumbersome. as rudimentary as it is, todm nonetheless provides a comprehensive basis for formulating an external data model for a temporally oriented database.  gad ariav