Transaction Chopping for Parallel Snapshot Isolation

Cerone, Andrea; Gotsman, Alexey; Yang, Hongseok

doi:10.1007/978-3-662-48653-5_26

“…Transaction chopping splits transactions into smaller pieces to obtain performance benefits and is correct if, for every serializable execution of the chopping, there exists an equivalent serializable execution of the original transactions [42]. Cerone et al [14,15] studied chopping under various isolation levels. Transaction chopping has no direct relationship with robustness testing against RC.…”

Section: Related Workmentioning

confidence: 99%

Robustness against read committed for transaction templates

Vandevoort

¹

,

Ketsman

²

,

Neven

³

2021

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The isolation level Multiversion Read Committed (RC), offered by many database systems, is known to trade consistency for increased transaction throughput. Sometimes, transaction workloads can be safely executed under RC obtaining the perfect isolation of serializability at the lower cost of RC. To identify such cases, we introduce an expressive model of transaction programs to better reason about the serializability of transactional workloads. We develop tractable algorithms to decide whether any possible schedule of a workload executed under RC is serializable (referred to as the robustness problem). Our approach yields robust subsets that are larger than those identified by previous methods. We provide experimental evidence that workloads that are robust against RC can be evaluated faster under RC compared to stronger isolation levels. We discuss techniques for making workloads robust against RC by promoting selective read operations to updates. Depending on the scenario, the performance improvements can be considerable. Robustness testing and safely executing transactions under the lower isolation level RC can therefore provide a direct way to increase transaction throughput without changing DBMS internals.

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“…Shasha et al [44] provide a graph based characterization for this correctness problem. This problem has been studied for different isolation levels such as SI [14] and parallel snapshot isolation [15] as well. However, in this case a correct chopping does not guarantee serializability.…”

Section: Other Approachesmentioning

confidence: 99%

Robustness against Read Committed for Transaction Templates

Vandevoort¹,

Ketsman²,

Koch³

et al. 2021

Preprint

0

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The isolation level Multiversion Read Committed (RC), offered by many database systems, is known to trade consistency for increased transaction throughput. Sometimes, transaction workloads can be safely executed under RC obtaining the perfect isolation of serializability at the lower cost of RC. To identify such cases, we introduce an expressive model of transaction programs to better reason about the serializability of transactional workloads. We develop tractable algorithms to decide whether any possible schedule of a workload executed under RC is serializable (referred to as the robustness problem). Our approach yields robust subsets that are larger than those identified by previous methods. We provide experimental evidence that workloads that are robust against RC can be evaluated faster under RC compared to stronger isolation levels. We discuss techniques for making workloads robust against RC by promoting selective read operations to updates. Depending on the scenario, the performance improvements can be considerable. Robustness testing and safely executing transactions under the lower isolation level RC can therefore provide a direct way to increase transaction throughput without changing DBMS internals.

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“…In order to formally characterise the weak behaviour and anomalies admitted by PSI, Cerone and Gotsman [14,15] formulated a declarative PSI specification. (In fact, they provide two equivalent specifications: one using dependency graphs proposed by Adya et al [5,7]; and the other using abstract executions.)…”

Section: A Declarative Specification Of Psi Stms In Ramentioning

confidence: 99%

“…It is straightforward to verify that our definition coincides with the dependency graph specification in [15]. As with [14,15], throughout this section, we take PSI execution graphs to be those in which E = T ⊆ (R ∪ W) \ U. That is, the PSI model handles transactional code only, consisting solely of read and write events (excluding updates).…”

Section: A Declarative Specification Of Psi Stms In Ramentioning

confidence: 99%

“…Although Cerone et al [15] proved their declarative PSI specification equivalent to an implementation strategy of PSI in a distributed system with replicated storage over causal consistency, their implementation is not suitable for reasoning about shared-memory programs. In particular, it cannot help the programmers determine how transactional and non-transactional accesses may interact.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

On Parallel Snapshot Isolation and Release/Acquire Consistency

Raad

¹

,

Lahav

²

,

Vafeiadis

³

2018

Programming Languages and Systems

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Abstract. Parallel snapshot isolation (PSI) is a standard transactional consistency model used in databases and distributed systems. We argue that PSI is also a useful formal model for software transactional memory (STM) as it has certain advantages over other consistency models. However, the formal PSI definition is given declaratively by acyclicity axioms, which most programmers find hard to understand and reason about.To address this, we develop a simple lock-based reference implementation for PSI built on top of the release-acquire memory model, a wellbehaved subset of the C/C++11 memory model. We prove that our implementation is sound and complete against its higher-level declarative specification.We further consider an extension of PSI allowing transactional and non-transactional code to interact, and provide a sound and complete reference implementation for the more general setting. Supporting this interaction is necessary for adopting a transactional model in programming languages.

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Transaction Chopping for Parallel Snapshot Isolation

Cited by 15 publications

References 25 publications

Robustness against read committed for transaction templates

Robustness against read committed for transaction templates

Robustness against Read Committed for Transaction Templates

On Parallel Snapshot Isolation and Release/Acquire Consistency

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