The prospect of achieving computational speedups by exploiting quantum phenomena makes the use processing units (QPUs) attractive for many algorithmic database problems. Query optimisation, which concerns problems that typically need to explore large search spaces, seems like an ideal match algorithms. We present first implementation join ordering, one most investigated and fundamental query optimisation problems, based on a reformulation quadratic binary unconstrained empirically...

JSON Schema is the de-facto standard schema language for data. The went through many minor revisions, but most recent versions of language, starting from Draft 2019-09, added two novel features, dynamic references and annotation-dependent validation, that change evaluation model. Modern name used to indicate all which are characterized by these new while Classical previous versions. These “modern” features make quite difficult understand have generated discussions about correct...

NoSQL data stores are commonly schema-less, providing no means for globally defining or managing the schema. While this offers great flexibility in early stages of application development, developers soon can experience heavy burden dealing with increasingly heterogeneous data. This paper targets schema evolution stores, complex task adapting and changing implicit structure stored. We discuss recommendations developer community on handling changes, introduce a simple, declarative language....

Data accumulating in data lakes can become inaccessible the long run when its semantics are not available. The heterogeneity of formats and sheer volumes collections prohibit cleaning unifying manually. Thus, tools for automated lake analysis great interest. In this paper, we target particular problem reconstructing schema evolution history from lakes. Knowing how is structured, structure has evolved over time, enables programmatic access to lake. By deriving a sequence versions, rather than...

This paper explores scalable implementation strategies for carrying out lazy schema evolution in NoSQL data stores. For decades, has been an evergreen database research. Yet new challenges arise the context of cloud-hosted backends: With all reads and writes charged by provider, migrating entire instance eagerly into a can be prohibitively expensive. Thus, migration may more cost-efficient, as legacy entities are only migrated case they actually accessed application. Related work shown that...

Various fields of science face a reproducibility crisis. For quantum software engineering as an emerging field, it is therefore imminent to focus on proper from the start. Yet provision reproduction packages almost universally lacking. Actionable advice how build such rare, particularly unfortunate in field with many contributions researchers backgrounds outside computer science. In this article, we argue rectify deficiency by proposing 1-2-3 approach for experiments: Using meta-generation...

Traditionally, when the code of a database management system (DBMS) needs to be updated, is restarted and clients suffer downtime, or provider instantiates hot-standby instances rolls over workload. We investigate third option, live patching DBMS binary. For certain changes, allows modify application in memory, without restart. The memory state all client connections can maintained. Although has been explored operating systems research community, it remains blind spot research. In this...

Building scalable web applications on top of NoSQL data stores is becoming common practice. Many these can easily be accessed programmatically, and do not enforce a schema. Software engineers design the model go, flexibility that crucial in agile software development. The typical tasks database schema management are now handled within application code, usually involving object mapper libraries. However, today's Integrated Development Environments (IDEs) lack proper tool support when it comes...

In recent years, various vendors have made quantum software frameworks available. Yet with vendor-specific frameworks, code portability seems at risk, especially in a field where hardware and libraries not yet reached consolidated state, even foundational aspects of the technologies are still flux. Accordingly, development vendor-independent programming languages is often suggested. This follows established architectural pattern introducing additional levels abstraction into stacks, thereby...

Effective buffer management is crucial for efficient in-memory and streaming XQuery processing. We propose a scheme which combines static dynamic analysis to keep main memory consumption low. Our approach relies on technique that we call active garbage collection actively purges buffers at runtime based the current status of query evaluation. have built prototype system practical fragment employs our scheme. The experimental results demonstrate significant impact combined reducing running time.

Building applications for processing data lakes is a software engineering challenge. We present Darwin, middleware that operate on variational data. This concerns with heterogeneous structure, usually stored within schema-flexible NoSQL database. Darwin assists application developers in essential and schema curation tasks: Upon request, extracts description, discovers the history of versions, proposes mappings between these versions. Users may interactively choose which are most realistic....

We demonstrate MigCast, a tool-based advisor for exploring data migration strategies in the context of developing NoSQL-backed applications. Users MigCast can consider their options evolving model along with legacy already persisted cloud-hosted production database. They explore alternative actions as financial costs are predicted respective to cloud provider chosen. Thereby they better equipped assess potential consequences imminent decisions. To this end, maintains an internal cost model,...

Providers of high-availability data stores need to roll out software updates without causing noticeable downtimes. For distributed like Redis Cluster, the state-of-the-art is a rolling update, where nodes are restarted in sequence. This requires preserving, restoring, and resynchronizing database state, which can significantly prolong for larger memory states, thus delay critical security fixes. In this article, we propose applying directly restarting any nodes. We present first fully...

We propose a new technique for the efficient search and navigation in XML documents streams. This takes string matching algorithms designed keyword flat strings into second dimension, to navigate tree structured data. consider important data management task of prefiltering (also called projection) as an application our approach. Different from existing schemes, we usually process only fractions input get by with very economical consumption both main memory processing time. Our experiments...

Machine learning (ML) based decision making is becoming commonplace. For persons affected by ML-based decisions, a certain level of transparency regarding the properties underlying ML model can be fundamental. In this vision paper, we propose to issue consumer labels for trained and published models. These primarily target machine lay persons, such as operators an system, executors subjects themselves. Provided that comprehensively capture characteristics model, consumers are enabled...

The design of the NoSQL schema has a direct impact on scalability web applications. Especially for developers with little experience in stores, risks inherent poor can be incalculable. Worse yet, issues will only manifest once application been deployed, and growing user base causes highly concurrent writes. In this paper, we present model checking approach to reveal bottlenecks schemas. Our draws formal methods from tree automata theory perform conservative static analysis both expected...

We consider the task of building Big Data software systems, offered as software-as-a-service. These applications are commonly backed by NoSQL data stores that address proverbial Vs processing: can handle large volumes and many systems do not enforce a global schema, to account for structural variety in data. Thus, engineers design model on go, flexibility is particularly crucial agile development. However, yet veracity changes when it comes structure persisted Yet this an inevitable...