http://dl.gi.de/handle/20.500.12116/36363 2026-07-21T16:06:23Z 2026-07-21T16:06:23Z Sattler, Kai-Uwe Kemper, Alfons Härder, Theo http://dl.gi.de/handle/20.500.12116/36407 2021-05-04T09:43:00Z 2020-01-01T00:00:00Z

Editorial Sattler, Kai-Uwe; Kemper, Alfons; Härder, Theo

2020-01-01T00:00:00Z http://dl.gi.de/handle/20.500.12116/36409 2021-05-04T09:43:00Z 2020-01-01T00:00:00Z

Dissertationen

2020-01-01T00:00:00Z Glombiewski, Nikolaus Götze, Philipp Körber, Michael Morgen, Andreas Seeger, Bernhard http://dl.gi.de/handle/20.500.12116/36410 2021-05-04T09:43:00Z 2020-01-01T00:00:00Z

Designing an Event Store for a Modern Three-layer Storage Hierarchy Glombiewski, Nikolaus; Götze, Philipp; Körber, Michael; Morgen, Andreas; Seeger, Bernhard Event stores face the difficult challenge of continuously ingesting massive temporal data streams while satisfying demanding query and recovery requirements. Many of today’s systems deal with multiple hardware-based trade-offs. For instance, long-term storage solutions balance keeping data in cheap secondary media (SSDs, HDDs) and performance-oriented main-memory caches. As an alternative, in-memory systems focus on performance, while sacrificing monetary costs, and, to some degree, recovery guarantees. The advent of persistent memory (PMem) led to a multitude of novel research proposals aiming to alleviate those trade-offs in various fields. So far, however, there is no proposal for a PMem-powered specialized event store. Based on ChronicleDB, we will present several complementary approaches for a three-layer architecture featuring main memory, PMem, and secondary storage. We enhance some of ChronicleDB’s components with PMem for better insertion and query performance as well as better recovery guarantees. At the same time, the three-layer architecture aims to keep the overall dollar cost of a system low. The limitations and opportunities of a PMem-enhanced event store serve as important groundwork for comprehensive system design exploiting a modern storage hierarchy.

2020-01-01T00:00:00Z Tetzel, Frank Lehner, Wolfgang Kasperovics, Romans http://dl.gi.de/handle/20.500.12116/36413 2021-05-04T09:43:00Z 2020-01-01T00:00:00Z

Efficient Compilation of Regular Path Queries Tetzel, Frank; Lehner, Wolfgang; Kasperovics, Romans Ad hoc code generation is a state-of-the-art processing paradigm for database execution engines. It minimizes resource consumption by generating specialized code, tailored and streamlined for the single query at hand. In this work, we apply ad hoc code generation to regular path queries (RPQs), an advanced query type in declarative graph query languages. We investigate code generation from multiple angles. We propose COAT, an embedded domain specific language (EDSL) in C++ to improve accessibility of code generation by simplifying the interaction with compiler APIs. Furthermore, we analyze and compare two back ends for COAT providing the just-in-time (JIT) compilation functionality: LLVM, a compiler framework popularly used in databases for code generation, and AsmJit, a JIT assembler with very low compilation latency. We evaluate various compilation techniques for RPQs on different synthetic graph workloads.

2020-01-01T00:00:00Z