Ground states in the Many Interacting Worlds approach

Recently the Many-Interacting-Worlds (MIW) approach to a quantum theory without wave functions was proposed. This approach leads quite naturally to numerical integrators of the Schr\"odinger equation. It has been suggested that such integrators may feature advantages over fixed-grid methods for higher numbers of degrees of freedom. However, as yet, little is known about concrete MIW models for more than one spatial dimension and/or more than one particle. In this work we develop the MIW approach further to treat arbitrary degrees of freedom, and provide a systematic study of a corresponding numerical implementation for computing one-particle ground and excited states in one dimension, and ground states in two spatial dimensions. With this step towards the treatment of higher degrees of freedom we hope to stimulate their further study.Comment: 16 pages, 8 figure

Online horizontal partitioning of heterogeneous data

In an increasing number of use cases, databases face the challenge of managing heterogeneous data. Heterogeneous data is characterized by a quickly evolving variety of entities without a common set of attributes. These entities do not show enough regularity to be captured in a traditional database schema. A common solution is to centralize the diverse entities in a universal table. Usually, this leads to a very sparse table. Although today’s techniques allow efficient storage of sparse universal tables, query efficiency is still a problem. Queries that address only a subset of attributes have to read the whole universal table includingmany irrelevant entities. Asolution is to use a partitioning of the table, which allows pruning partitions of irrelevant entities before they are touched. Creating and maintaining such a partitioning manually is very laborious or even infeasible, due to the enormous complexity. Thus an autonomous solution is desirable. In this article, we define the Online Partitioning Problem for heterogeneous data. We sketch how an optimal solution for this problem can be determined based on hypergraph partitioning. Although it leads to the optimal partitioning, the hypergraph approach is inappropriate for an implementation in a database system. We present Cinderella, an autonomous online algorithm for horizontal partitioning of heterogeneous entities in universal tables. Cinderella is designed to keep its overhead low by operating online; it incrementally assigns entities to partition while they are touched anyway duringmodifications. This enables a reasonable physical database design at runtime instead of static modeling

CoDEL - A Relationally Complete Language for Database Evolution

Software developers adapt to the fast-moving nature of software systems with agile development techniques. However, database developers lack the tools and concepts to keep pace. Data, already existing in a running product, needs to be evolved accordingly, usually by manually written SQL scripts. A promising approach in database research is to use a declarative database evolution language, which couples both schema and data evolution into intuitive operations. Existing database evolution languages focus on usability but did not aim for completeness. However, this is an inevitable prerequisite for reasonable database evolution to avoid complex and error-prone workarounds. We argue that relational completeness is the feasible expressiveness for a database evolution language. Building upon an existing language, we introduce CoDEL. We define its semantic using relational algebra, propose a syntax, and show its relational completeness

InVerDa - co-existing Schema Versions Made Foolproof

In modern software landscapes multiple applications usually share one database as their single point of truth. All these applications will evolve over time by their very nature. Often former versions need to stay available, so database developers find themselves maintaining co-existing schema version of multiple applications in multiple versions. This is highly error-prone and accounts for significant costs in software projects, as developers realize the translation of data accesses between schema versions with hand-written delta code. In this demo, we showcase INVERDA, a tool for integrated, robust, and easy to use database versioning. We rethink the way of specifying the evolution to new schema versions. Using the richer semantics of a descriptive database evolution language, we generate all required artifacts automatically and make database versioning foolproof

Listen to the customer: Model-driven database design

In modern IT landscapes, databases are subject to a major role change. Especially in Service-Oriented Architectures, databases are more and more frequently dedicated to a single application. Therefore, it is even more important to reflect the application requirements in their design. Software developers and application experts formulate application requirements in software models. Hence, we obviously need to bridge the gap to the software world and directly derive a database design from the software models used in application development and maintenance. We introduce this concept as model-driven database design. In this paper, we present the architecture principles of a model-driven database design tool and details on the enumeration and evaluation of logical database designs