Publications de Christoph Koch

High-dimensional Data Cubes

Christoph Koch, Sachin Basil John, Peter Lindner

We introduce an approach to supporting high-dimensional data cubes at interactive query speeds and moderate storage cost. Our approach is based on binary(-domain) data cubes that are judiciously partially materialized; the missing information can be quickl ...

Association for Computing Machinery (ACM)2025

Using Process Calculus for Optimizing Data and Computation Sharing in Complex Stateful Parallel Computations

Christoph Koch

We propose novel techniques that exploit data and computation sharing to improve the performance of complex stateful parallel computations, like agent-based simulations. Parallel computations are translated into behavioral equations, a novel formalism laye ...

Association for Computing Machinery (ACM)2025

Generalizing Bulk-Synchronous Parallel Processing for Data Science: From Data to Threads and Agent-Based Simulations

Christoph Koch, Val Tannen, Zilu Tian, Peter Lindner

We generalize the bulk-synchronous parallel (BSP) processing model to make it better support agent-based simulations. Such simulations frequently exhibit hierarchical structure in their communication patterns which can be exploited to improve performance. ...

2023

Aggregation and Exploration of High-Dimensional Data Using the Sudokube Data Cube Engine

Christoph Koch, Sachin Basil John, Peter Lindner, Zhekai Jiang

We present Sudokube, a novel system that supports interactive speed querying on high-dimensional data using partially materialized data cubes. Given a storage budget, it judiciously chooses what projections to precompute and materialize during cube constru ...

Association for Computing Machinery2023

ROBUSTNESS AGAINST READ COMMITTED FOR TRANSACTION TEMPLATES WITH FUNCTIONAL CONSTRAINTS

Christoph Koch

Vandevoort, B. Ketsman, C. Koch, and F. Neven.The popular isolation level Multiversion Read Committed (RC) trades some of the strong guarantees of serializability for increased transaction throughput. Sometimes, transaction workloads can be safely executed ...

2023

When is it safe to run a transactional workload under Read Committed?

Christoph Koch, Bas Ketsman

The popular isolation level multiversion Read Committed (RC) exchanges some of the strong guarantees of serializability for increased transaction throughput. Nevertheless, transaction workloads can sometimes be executed under RC while still guaranteeing se ...

ASSOC COMPUTING MACHINERY2023

Deciding Robustness for Lower SQL Isolation Levels

Christoph Koch, Bas Ketsman

While serializability always guarantees application correctness, lower isolation levels can be chosen to improve transaction throughput at the risk of introducing certain anomalies. A set of transactions is robust against a given isolation level if every p ...

ASSOC COMPUTING MACHINERY2022

Robustness Against Read Committed: A Free Transactional Lunch

Christoph Koch, Bas Ketsman

Transaction processing is a central part of most database applications. While serializability remains the gold standard for desirable transactional semantics, many database systems offer improved transaction throughput at the expense of introducing potenti ...

ASSOC COMPUTING MACHINERY2022

Concurrency control for database theorists

Christoph Koch, Bas Ketsman

The aim of this paper is to serve as a lightweight introduction to concurrency control for database theorists through a uniform presentation of the work on robustness against Multiversion Read Committed and Snapshot Isolation. ...

ASSOC COMPUTING MACHINERY2022

High-dimensional Data Cubes

Christoph Koch, Sachin Basil John

This paper introduces an approach to supporting high-dimensional data cubes at interactive query speeds and moderate storage cost. The approach is based on binary(-domain) data cubes that are judiciously partially materialized; the missing information can ...

2022

High-dimensional Data Cubes

Christoph Koch, Sachin Basil John

This paper introduces an approach to supporting high-dimensional data cubes at interactive query speeds and moderate storage cost. The approach is based on binary(-domain) data cubes that are judiciously partially materialized; the missing information can ...

ASSOC COMPUTING MACHINERY2022

Robustness against Read Committed for Transaction Templates

Christoph Koch, Bas Ketsman

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 ...

ASSOC COMPUTING MACHINERY2021

Unidirectional Kondo scattering in layered NbS2

Helmuth Berger, László Forró, Oleg Yazyev, Christoph Koch, Edoardo Martino, Quansheng Wu, Shengnan Zhang, Philip Johannes Walter Moll, Matthias Carsten Putzke, Konstantin Semeniuk

Crystalline defects can modify quantum interactions in solids, causing unintuitive, even favourable, properties such as quantum Hall effect or superconducting vortex pinning. Here we present another example of this notion-an unexpected unidirectional Kondo ...

NATURE PORTFOLIO2021

Data transformer apparatus

Babak Falsafi, Christoph Koch, Hussein Kassir, Mario Paulo Drumond Lages De Oliveira, Arash Pourhabibi Zarandi, Mark Johnathon Sutherland, Zilu Tian, Siddharth Gupta

Data transformer apparatus comprising at least a dispatcher module (D), a reader module (R), a converter module (C) and a writer module (W). The dispatcher module (D) is configured to: receive a data transformation request (DTR) including: a first informat ...

2021

Deciding Robustness for Lower SQL Isolation Levels

Christoph Koch, Bas Ketsman

While serializability always guarantees application correctness, lower isolation levels can be chosen to improve transaction throughput at the risk of introducing certain anomalies. A set of transactions is robust against a given isolation level if every p ...

ASSOC COMPUTING MACHINERY2020

Optimus Prime: Accelerating Data Transformation in Servers

Babak Falsafi, Christoph Koch, Hussein Kassir, Mario Paulo Drumond Lages De Oliveira, Arash Pourhabibi Zarandi, Mark Johnathon Sutherland, Zilu Tian, Siddharth Gupta

Modern online services are shifting away from monolithic applications to loosely-coupled microservices because of their improved scalability, reliability, programmability and development velocity. Microservices communicating over the datacenter network req ...

ACM2020

Compiler Generation for Performance-Oriented Embedded DSLs (Short Paper)

Vojin Jovanovic, Christoph Koch, Amir Shaikhha

In this paper, we present a framework for generating optimizing compilers for performance-oriented embedded DSLs (EDSLs). This framework provides facilities to automatically generate the boilerplate code required for building DSL compilers on top of the ex ...

ASSOC COMPUTING MACHINERY2019

Unifying Analytic and Statically-Typed Quasiquotes

Christoph Koch, Amir Shaikhha, Lionel Emile Vincent Parreaux

Metaprograms are programs that manipulate (generate, analyze and evaluate) other programs. These tasks are greatly facilitated by quasiquotation, a technique to construct and deconstruct program fragments using quoted code templates expressed in the syntax ...

2018

Building Efficient Query Engines in a High-Level Language

Christoph Koch, Amir Shaikhha

2018

Push versus pull-based loop fusion in query engines

Christoph Koch, Amir Shaikhha, Mohammad Dashti Rahmat Abadi

2018