http://dl.gi.de/handle/20.500.12116/21088 Fri, 24 Jul 2026 11:05:17 GMT 2026-07-24T11:05:17Z http://dl.gi.de:80/bitstream/id/ea79b25d-b19c-4b1c-ad62-bd1f3a59a825/ http://dl.gi.de/handle/20.500.12116/21088 http://dl.gi.de/handle/20.500.12116/2453 Privacy preserving record linkage with ppjoin Sehili, Ziad; Kolb, Lars; Borgs, Christian; Schnell, Rainer; Rahm, Erhard Seidl, Thomas; Ritter, Norbert; Schöning, Harald; Sattler, Kai-Uwe; Härder, Theo; Friedrich, Steffen; Wingerath, Wolfram Privacy-preserving record linkage (PPRL) becomes increasingly important to match and integrate records with sensitive data. PPRL not only has to preserve the anonymity of the persons or entities involved but should also be highly efficient and scalable to large datasets. We therefore investigate how to adapt PPJoin, one of the fastest approaches for regular record linkage, to PPRL resulting in a new approach called P4Join. The use of bit vectors for PPRL also allows us to devise a parallel execution of P4Join on GPUs. We evaluate the new approaches and compare their efficiency with a PPRL approach based on multibit trees. Thu, 01 Jan 2015 00:00:00 GMT http://dl.gi.de/handle/20.500.12116/2453 2015-01-01T00:00:00Z http://dl.gi.de/handle/20.500.12116/2454 D2Pt: Privacy-Aware Multiparty Data Publication Nielsen, Jan Hendrik; Janusz, Daniel; Taeschner, Jochen; Freytag, Johann-Christoph Seidl, Thomas; Ritter, Norbert; Schöning, Harald; Sattler, Kai-Uwe; Härder, Theo; Friedrich, Steffen; Wingerath, Wolfram Today, publication of medical data faces high legal barriers. On the one hand, publishing medical data is important for medical research. On the other hand, it is neccessary to protect peoples' privacy by ensuring that the relationship between individuals and their related medical data remains unknown to third parties. Various data anonymization techniques remove as little identifying information as possible to maintain a high data utility while satisfying the strict demands of privacy laws. Current research in this area proposes a multitude of concepts for data anonymization. The concept of k-anonymity allows data publication by hiding identifying information without losing its semantics. Based on k-anonymity, the concept of t-closeness incorporates semantic relationships between personal data values, therefore increasing the strength of the anonymization. However, these concepts are restricted to a centralized data source. In this paper, we extend existing data privacy mechanisms to enable joint data publication among multiple participating institutions. In particular, we adapt the concept of t-closeness for distributed data anonymization. We introduce Distributed two-Party t-closeness (D2Pt), a protocol that utilizes cryptographic algorithms to avoid a central component when anonymizing data adhering the t-closeness property. That is, without a trusted third party, we achieve a data privacy based on the notion of t-closeness. Thu, 01 Jan 2015 00:00:00 GMT http://dl.gi.de/handle/20.500.12116/2454 2015-01-01T00:00:00Z http://dl.gi.de/handle/20.500.12116/2452 Towards Automated Polyglot Persistence Schaarschmidt, Michael; Gessert, Felix; Ritter, Norbert Seidl, Thomas; Ritter, Norbert; Schöning, Harald; Sattler, Kai-Uwe; Härder, Theo; Friedrich, Steffen; Wingerath, Wolfram In this paper, we present an innovative solution for providing automated polyglot persistence based on service level agreements defined over functional and non-functional requirements of database systems. Complex applications require polyglot persistence to deal with a wide range of database related needs. Until now, the overhead and the required know-how to manage multiple database systems prevents many applications from employing efficient polyglot persistence solutions. Instead, developers are often forced to implement one-size-fits-all solutions that do not scale well and cannot easily be upgraded. Therefore, we introduce the concept for a Polyglot Persistence Mediator (PPM), which allows for runtime decisions on routing data to different backends according to schema-based annotations. This enables applications to either employ polyglot persistence right from the beginning or employ new systems at any point with minimal overhead. We have implemented and evaluated the concept of automated polyglot persistence for a REST-based Database-as-a-Service setting. Evaluations were performed on various EC2 setups, showing a scalable writeperformance increase of 50-100\% for a typical polyglot persistence scenario as well as drastically reduced latencies for reads and queries. Thu, 01 Jan 2015 00:00:00 GMT http://dl.gi.de/handle/20.500.12116/2452 2015-01-01T00:00:00Z http://dl.gi.de/handle/20.500.12116/2451 The cache sketch: revisiting expiration-based caching in the age of cloud data management Gessert, Felix; Schaarschmidt, Michael; Wingerath, Wolfram; Friedrich, Steffen; Ritter, Norbert Seidl, Thomas; Ritter, Norbert; Schöning, Harald; Sattler, Kai-Uwe; Härder, Theo; Friedrich, Steffen; Wingerath, Wolfram The expiration-based caching model of the web is generally considered irreconcilable with the dynamic workloads of cloud database services, where expiration dates are not known in advance. In this paper, we present the Cache Sketch data structure which makes expiration-based caching of database records feasible with rich tunable consistency guarantees. The Cache Sketch enables database services to leverage the large existing caching infrastructure of content delivery networks, browser caches and web caches to provide low latency and high scalability. The Cache Sketch employs Bloom filters to create compact representations of potentially stale records to transfer the task of cache coherence to clients. Furthermore, it also minimizes the number of invalidations the service has to perform on caches that support them (e.g., CDNs). With different age-control policies the Cache Sketch achieves very high cache hit ratios with arbitrarily low stale read probabilities. We present the Constrained Adaptive TTL Es- timator to provide cache expiration dates that optimize the performance of the Cache Sketch and invalidations. To quantify the performance gains and to derive workloadoptimal Cache Sketch parameters, we introduce the YCSB Monte-Carlo Caching Simulator (YMCA), a generic framework for simulating the performance and consistency characteristics of any caching and replication topology. We also provide empirical evidence for the efficiency of the Cache Sketch construction and the real-world latency reductions of database workloads under CDN-caching. Thu, 01 Jan 2015 00:00:00 GMT http://dl.gi.de/handle/20.500.12116/2451 2015-01-01T00:00:00Z