Liuba Shrira - Academia.edu (original) (raw)

Papers by Liuba Shrira

Research paper thumbnail of Mobilebuddy: consistent client-to-client exchange in disconnected collaborative groups

The thesis presents MobileBuddy, a novel data caching system that improves availability and perfo... more The thesis presents MobileBuddy, a novel data caching system that improves availability and performance for collaborative applications while maintaining data consistency in a disconnected environment or over a Wide Area Network. MobileBuddy supports mobile exchange—a novel capability for disconnected client-to-client data and reservation transfer. Mobile exchange makes mobile computing more useful because it allows users to accomplish collaborative work that would be impossible in other systems. Collaborators disconnected from servers can acquire missing or more recent data, and can obtain reservations that guarantee independent transaction validation. The thesis describes the new techniques we developed to implement mobile exchange. The technique for data and reservation transfer combines support for coarse-grained data transfer with fine-grained validation, in a way that avoids the problem of false sharing. The technique for supporting type-specific reservations is more flexible a...

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Research paper thumbnail of RID: Deduplicating Snapshot Computations

Proceedings of the 2020 ACM SIGMOD International Conference on Management of Data, 2020

One can audit SQL applications by running SQL programs over sequences of persistent snapshots, bu... more One can audit SQL applications by running SQL programs over sequences of persistent snapshots, but care is needed to avoid wasteful duplicate computation. This paper describes the design, implementation, and performance of RID, the first language-independent optimization framework that eliminates duplicate computations in SQL programs running over low-level snapshots by exploiting snapshot metadata efficiently.

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Research paper thumbnail of Leader in the Prese : q . ce of Faults : a Ring as a Special Case

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Research paper thumbnail of Cross-chain deals and adversarial commerce

Proceedings of the VLDB Endowment, 2019

Modern distributed data management systems face a new challenge: how can autonomous, mutually-dis... more Modern distributed data management systems face a new challenge: how can autonomous, mutually-distrusting parties cooperate safely and effectively? Addressing this challenge brings up questions familiar from classical distributed systems: how to combine multiple steps into a single atomic action, how to recover from failures, and how to synchronize concurrent access to data. Nevertheless, each of these issues requires rethinking when participants are autonomous and potentially adversarial. We propose the notion of a cross-chain deal , a new way to structure complex distributed computations that manage assets in an adversarial setting. Deals are inspired by classical atomic transactions, but are necessarily different, in important ways, to accommodate the decentralized and untrusting nature of the exchange. We describe novel safety and liveness properties, along with two alternative protocols for implementing cross-chain deals in a system of independent blockchain ledgers. One protoc...

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Research paper thumbnail of Ownership types for object encapsulation

Proceedings of the 30th ACM SIGPLAN-SIGACT symposium on Principles of programming languages - POPL '03, 2003

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Research paper thumbnail of BuddyCache

Proceedings of the 17th ACM SIGPLAN conference on Object-oriented programming, systems, languages, and applications - OOPSLA '02, 2002

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Research paper thumbnail of The Impact of Timestamp Granularity in Optimistic Concurrency Control

ArXiv, 2018

Optimistic concurrency control (OCC) can exploit the strengths of parallel hardware to provide ex... more Optimistic concurrency control (OCC) can exploit the strengths of parallel hardware to provide excellent performance for uncontended transactions, and is popular in high-performance in-memory databases and transactional systems. But at high contention levels, OCC is susceptible to frequent aborts, leading to wasted work and degraded performance. Contention managers, mixed optimistic/pessimistic concurrency control algorithms, and novel optimistic-inspired concurrency control algorithms, such as TicToc, aim to address this problem, but these mechanisms introduce sometimes-high overheads of their own. We show that in real-world benchmarks, traditional OCC can outperform these alternative mechanisms by simply adding fine-grained version timestamps (using different timestamps for disjoint components of each record). With fine-grained timestamps, OCC gets 1.14x TicToc's throughput in TPC-C at 128 cores (previous work reported TicToc having 1.8x higher throughput than OCC at 80 hypert...

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Research paper thumbnail of From Internet to ActiveNet

providing an opportunity to explore alternatives. Researchers at Bellcore, BBN, CMU, Columbia,Joh... more providing an opportunity to explore alternatives. Researchers at Bellcore, BBN, CMU, Columbia,John Hopkins, U. Arizona, UCLA, U. Penn and U. Washington have agreed to work towards thisgoal and other organizations, in both industry and academia, have expressed interest inparticipating.Our work is motivated by user "pull", as well as technology "push". The "pull" comes from thead hoc collection of firewalls, Web

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Research paper thumbnail of How to scale transactional storage systems

Applications of the future will need to support large numbers of clients and will require scalabl... more Applications of the future will need to support large numbers of clients and will require scalable storage systems that allow state to be shared reliably. Recent research in distributed file systems provides technology that increases the scalability of storage systems. But file systems only support sharing with weak consistency guarantees and can not support applications that require transactional consistency. The challenge is how to provide scalable storage systems that support transactional applications.We are developing technology for scalable transactional storage systems. Our approach combines scalable caching and coherence techniques developed in serverless file systems and DSM systems, with recovery techniques developed in traditional databases. This position paper describes the design rationale for split caching, a new scalable memory management technique for network-based transactional object storage systems, and fragment reconstruction, a new coherence protocol that suppor...

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Research paper thumbnail of A Modular and Efficient Past State System for Berkeley DB

Applications often need to analyze past states to predict trends and support audits. Adding effic... more Applications often need to analyze past states to predict trends and support audits. Adding efficient and nondisruptive support for consistent past-state analysis requires after-the-fact modification of the data store, a significant challenge for today's systems. This paper describes Retro, a new system for supporting consistent past state analysis in Berkeley DB. The key novelty of Retro is an efficient yet simple and robust implementation method, imposing 4% worst-case overhead. Unlike prior approaches, Retro protocols, backed by a formal specification, extend standard transaction protocols in a modular way, requiring minimal data store modification (about 250 lines of BDB code).

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Research paper thumbnail of Distributed Object Man-agement in Thor

Thor is a new object-oriented database management system (OODBMS),intended to be used in heteroge... more Thor is a new object-oriented database management system (OODBMS),intended to be used in heterogeneous distributed systems to allow programswritten in different programming languages to share objects in aconvenient manner. Thor objects are persistent in spite of failures, arehighly likely to be accessible whenever they are needed, and can be structuredto reflect the kinds of information of interest to users. Thor

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Research paper thumbnail of Time travel in the virtualized past: Cheap fares and first class seats

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Research paper thumbnail of Hq replication: Properties and optimizations

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Research paper thumbnail of Trust but Check: Mutable Objects in Untrusted Cooperative Caches

Pos, 1998

Cooperative caching is known to be an effective tech- nique for improving the performance of larg... more Cooperative caching is known to be an effective tech- nique for improving the performance of large scale dis- tributed storage systems (5, 6, 7, 11, 1). Nevertheless, current cooperative caching techniques work only in en- vironments when machines trust one other, a requirement that is likely to become more and more difficult to satisfy. We describe a novel technique for

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Research paper thumbnail of Type-aware transactions for faster concurrent code

Proceedings of the Eleventh European Conference on Computer Systems - EuroSys '16, 2016

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Research paper thumbnail of Lazy modular upgrades in persistent object stores

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Research paper thumbnail of Thresher: An Efficient Storage Manager for Copy-on-write Snapshots

Proceedings of the Annual Conference on Usenix 06 Annual Technical Conference, 2006

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Research paper thumbnail of Device and Method for Enabling Long-Lived Snapshots

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Research paper thumbnail of Methodological construction of reliable distributed algorithms

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Research paper thumbnail of Hybrid Caching for Scalable Object Systems (Think Globally, Act Locally)

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Research paper thumbnail of Mobilebuddy: consistent client-to-client exchange in disconnected collaborative groups

The thesis presents MobileBuddy, a novel data caching system that improves availability and perfo... more The thesis presents MobileBuddy, a novel data caching system that improves availability and performance for collaborative applications while maintaining data consistency in a disconnected environment or over a Wide Area Network. MobileBuddy supports mobile exchange—a novel capability for disconnected client-to-client data and reservation transfer. Mobile exchange makes mobile computing more useful because it allows users to accomplish collaborative work that would be impossible in other systems. Collaborators disconnected from servers can acquire missing or more recent data, and can obtain reservations that guarantee independent transaction validation. The thesis describes the new techniques we developed to implement mobile exchange. The technique for data and reservation transfer combines support for coarse-grained data transfer with fine-grained validation, in a way that avoids the problem of false sharing. The technique for supporting type-specific reservations is more flexible a...

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Research paper thumbnail of RID: Deduplicating Snapshot Computations

Proceedings of the 2020 ACM SIGMOD International Conference on Management of Data, 2020

One can audit SQL applications by running SQL programs over sequences of persistent snapshots, bu... more One can audit SQL applications by running SQL programs over sequences of persistent snapshots, but care is needed to avoid wasteful duplicate computation. This paper describes the design, implementation, and performance of RID, the first language-independent optimization framework that eliminates duplicate computations in SQL programs running over low-level snapshots by exploiting snapshot metadata efficiently.

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Research paper thumbnail of Leader in the Prese : q . ce of Faults : a Ring as a Special Case

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Cross-chain deals and adversarial commerce

Proceedings of the VLDB Endowment, 2019

Modern distributed data management systems face a new challenge: how can autonomous, mutually-dis... more Modern distributed data management systems face a new challenge: how can autonomous, mutually-distrusting parties cooperate safely and effectively? Addressing this challenge brings up questions familiar from classical distributed systems: how to combine multiple steps into a single atomic action, how to recover from failures, and how to synchronize concurrent access to data. Nevertheless, each of these issues requires rethinking when participants are autonomous and potentially adversarial. We propose the notion of a cross-chain deal , a new way to structure complex distributed computations that manage assets in an adversarial setting. Deals are inspired by classical atomic transactions, but are necessarily different, in important ways, to accommodate the decentralized and untrusting nature of the exchange. We describe novel safety and liveness properties, along with two alternative protocols for implementing cross-chain deals in a system of independent blockchain ledgers. One protoc...

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Research paper thumbnail of Ownership types for object encapsulation

Proceedings of the 30th ACM SIGPLAN-SIGACT symposium on Principles of programming languages - POPL '03, 2003

Bookmarks Related papers MentionsView impact

Research paper thumbnail of BuddyCache

Proceedings of the 17th ACM SIGPLAN conference on Object-oriented programming, systems, languages, and applications - OOPSLA '02, 2002

Bookmarks Related papers MentionsView impact

Research paper thumbnail of The Impact of Timestamp Granularity in Optimistic Concurrency Control

ArXiv, 2018

Optimistic concurrency control (OCC) can exploit the strengths of parallel hardware to provide ex... more Optimistic concurrency control (OCC) can exploit the strengths of parallel hardware to provide excellent performance for uncontended transactions, and is popular in high-performance in-memory databases and transactional systems. But at high contention levels, OCC is susceptible to frequent aborts, leading to wasted work and degraded performance. Contention managers, mixed optimistic/pessimistic concurrency control algorithms, and novel optimistic-inspired concurrency control algorithms, such as TicToc, aim to address this problem, but these mechanisms introduce sometimes-high overheads of their own. We show that in real-world benchmarks, traditional OCC can outperform these alternative mechanisms by simply adding fine-grained version timestamps (using different timestamps for disjoint components of each record). With fine-grained timestamps, OCC gets 1.14x TicToc's throughput in TPC-C at 128 cores (previous work reported TicToc having 1.8x higher throughput than OCC at 80 hypert...

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Research paper thumbnail of From Internet to ActiveNet

providing an opportunity to explore alternatives. Researchers at Bellcore, BBN, CMU, Columbia,Joh... more providing an opportunity to explore alternatives. Researchers at Bellcore, BBN, CMU, Columbia,John Hopkins, U. Arizona, UCLA, U. Penn and U. Washington have agreed to work towards thisgoal and other organizations, in both industry and academia, have expressed interest inparticipating.Our work is motivated by user "pull", as well as technology "push". The "pull" comes from thead hoc collection of firewalls, Web

Bookmarks Related papers MentionsView impact

Research paper thumbnail of How to scale transactional storage systems

Applications of the future will need to support large numbers of clients and will require scalabl... more Applications of the future will need to support large numbers of clients and will require scalable storage systems that allow state to be shared reliably. Recent research in distributed file systems provides technology that increases the scalability of storage systems. But file systems only support sharing with weak consistency guarantees and can not support applications that require transactional consistency. The challenge is how to provide scalable storage systems that support transactional applications.We are developing technology for scalable transactional storage systems. Our approach combines scalable caching and coherence techniques developed in serverless file systems and DSM systems, with recovery techniques developed in traditional databases. This position paper describes the design rationale for split caching, a new scalable memory management technique for network-based transactional object storage systems, and fragment reconstruction, a new coherence protocol that suppor...

Bookmarks Related papers MentionsView impact

Research paper thumbnail of A Modular and Efficient Past State System for Berkeley DB

Applications often need to analyze past states to predict trends and support audits. Adding effic... more Applications often need to analyze past states to predict trends and support audits. Adding efficient and nondisruptive support for consistent past-state analysis requires after-the-fact modification of the data store, a significant challenge for today's systems. This paper describes Retro, a new system for supporting consistent past state analysis in Berkeley DB. The key novelty of Retro is an efficient yet simple and robust implementation method, imposing 4% worst-case overhead. Unlike prior approaches, Retro protocols, backed by a formal specification, extend standard transaction protocols in a modular way, requiring minimal data store modification (about 250 lines of BDB code).

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Research paper thumbnail of Distributed Object Man-agement in Thor

Thor is a new object-oriented database management system (OODBMS),intended to be used in heteroge... more Thor is a new object-oriented database management system (OODBMS),intended to be used in heterogeneous distributed systems to allow programswritten in different programming languages to share objects in aconvenient manner. Thor objects are persistent in spite of failures, arehighly likely to be accessible whenever they are needed, and can be structuredto reflect the kinds of information of interest to users. Thor

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Research paper thumbnail of Time travel in the virtualized past: Cheap fares and first class seats

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Hq replication: Properties and optimizations

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Trust but Check: Mutable Objects in Untrusted Cooperative Caches

Pos, 1998

Cooperative caching is known to be an effective tech- nique for improving the performance of larg... more Cooperative caching is known to be an effective tech- nique for improving the performance of large scale dis- tributed storage systems (5, 6, 7, 11, 1). Nevertheless, current cooperative caching techniques work only in en- vironments when machines trust one other, a requirement that is likely to become more and more difficult to satisfy. We describe a novel technique for

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Type-aware transactions for faster concurrent code

Proceedings of the Eleventh European Conference on Computer Systems - EuroSys '16, 2016

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Research paper thumbnail of Lazy modular upgrades in persistent object stores

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Thresher: An Efficient Storage Manager for Copy-on-write Snapshots

Proceedings of the Annual Conference on Usenix 06 Annual Technical Conference, 2006

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Device and Method for Enabling Long-Lived Snapshots

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Methodological construction of reliable distributed algorithms

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Hybrid Caching for Scalable Object Systems (Think Globally, Act Locally)

Bookmarks Related papers MentionsView impact