Viktor Leis
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View article: Moving on From Group Commit: Autonomous Commit Enables High Throughput and Low Latency on NVMe SSDs
Moving on From Group Commit: Autonomous Commit Enables High Throughput and Low Latency on NVMe SSDs Open
Achieving both high throughput and low commit latency has long been a difficult challenge for Database Management Systems (DBMSs). As we show in this paper, existing commit processing protocols fail to fully leverage modern NVMe SSDs to de…
View article: Oltp in the cloud: architectures, tradeoffs, and cost
Oltp in the cloud: architectures, tradeoffs, and cost Open
What is the best architecture for cloud OLTP systems? How costly is it to run a specific workload? Which and how many hardware instances should be provisioned? To answer such questions systematically, we develop an analytical model framewo…
View article: Managing Very Large Datasets on Directly Attached NVMe Arrays
Managing Very Large Datasets on Directly Attached NVMe Arrays Open
High-performance solid-state drives based on flash memory have replaced hard disks as the primary storage medium. Modern servers can host ten or more NVMe SSDs, and the aggregate bandwidth is approaching main memory bandwidth. In response …
View article: Succinct range filters
Succinct range filters Open
We present the Succinct Range Filter (SuRF), a fast and compact data structure for approximate membership tests. Unlike traditional Bloom filters, SuRF supports both single-key lookups and common range queries, such as range counts. SuRF i…
View article: RDMA Communciation Patterns
RDMA Communciation Patterns Open
Remote Direct Memory Access (RDMA) is a networking protocol that provides high bandwidth and low latency accesses to a remote node’s main memory. Although there has been much work around RDMA, such as building libraries on top of RDMA or e…
View article: Building blocks for persistent memory
Building blocks for persistent memory Open
I/O latency and throughput are two of the major performance bottlenecks for disk-based database systems. Persistent memory (PMem) technologies, like Intel’s Optane DC persistent memory modules, promise to bridge the gap between NAND-based …
View article: Succinct Range Filters
Succinct Range Filters Open
We present the Succinct Range Filter (SuRF), a fast and compact data structure for approximate membership tests. Unlike traditional Bloom filters, SuRF supports both single-key lookups and common range queries: open-range queries, closed-r…
View article: Rethinking Logging, Checkpoints, and Recovery for High-Performance Storage Engines
Rethinking Logging, Checkpoints, and Recovery for High-Performance Storage Engines Open
For decades, ARIES has been the standard for logging and recovery in database systems. ARIES offers important features like support for arbitrary workloads, fuzzy checkpoints, and transparent index recovery. Nevertheless, many modern in-me…
View article: Tree-Encoded Bitmaps
Tree-Encoded Bitmaps Open
We propose a novel method to represent compressed bitmaps. Similarly to existing bitmap compression schemes, we exploit the compression potential of bitmaps populated with consecutive identical bits, i.e., 0-runs and 1-runs. But in contras…
View article: Efficient Query Processing with Optimistically Compressed Hash Tables & Strings in the USSR
Efficient Query Processing with Optimistically Compressed Hash Tables & Strings in the USSR Open
Modern query engines rely heavily on hash tables for query processing. Overall query performance and memory footprint is often determined by how hash tables and the tuples within them are represented. In this work, we propose three complem…
View article: Low-Latency Communication for Fast DBMS Using RDMA and Shared Memory
Low-Latency Communication for Fast DBMS Using RDMA and Shared Memory Open
While hardware and software improvements greatly accelerated modern database systems' internal operations, the decades-old stream-based Socket API for external communication is still unchanged. We show experimentally, that for modern high-…
View article: Persistent Memory I/O Primitives
Persistent Memory I/O Primitives Open
I/O latency and throughput is one of the major performance bottlenecks for disk-based database systems. Upcoming persistent memory (PMem) technologies, like Intel's Optane DC Persistent Memory Modules, promise to bridge the gap between NAN…
View article: Estimating Cardinalities with Deep Sketches
Estimating Cardinalities with Deep Sketches Open
We introduce Deep Sketches, which are compact models of databases that allow us to estimate the result sizes of SQL queries. Deep Sketches are powered by a new deep learning approach to cardinality estimation that can capture correlations …
View article: 4.-8. März 2019
4.-8. März 2019 Open
The Hyper database system was started as an academic project at Technical University Munich. In 2016, the commercial spin-off of the academic Hyper database system was acquired by Tableau, a leader in the analytics and business intelligenc…
View article: Learned Cardinalities: Estimating Correlated Joins with Deep Learning
Learned Cardinalities: Estimating Correlated Joins with Deep Learning Open
We describe a new deep learning approach to cardinality estimation. MSCN is a multi-set convolutional network, tailored to representing relational query plans, that employs set semantics to capture query features and true cardinalities. MS…
View article: Learned Cardinalities: Estimating Correlated Joins with Deep Learning
Learned Cardinalities: Estimating Correlated Joins with Deep Learning Open
We describe a new deep learning approach to cardinality estimation. MSCN is a multi-set convolutional network, tailored to representing relational query plans, that employs set semantics to capture query features and true cardinalities. MS…
View article: Everything you always wanted to know about compiled and vectorized queries but were afraid to ask
Everything you always wanted to know about compiled and vectorized queries but were afraid to ask Open
The query engines of most modern database systems are either based on vectorization or data-centric code generation. These two state-of-the-art query processing paradigms are fundamentally different in terms of system structure and query e…
View article: SuRF
SuRF Open
We present the Succinct Range Filter (SuRF), a fast and compact data structure for approximate membership tests. Unlike traditional Bloom filters, SuRF supports both single-key lookups and common range queries: open-range queries, closed-r…
View article: Adaptive Execution of Compiled Queries
Adaptive Execution of Compiled Queries Open
Compiling queries to machine code is arguably the most efficient way for executing queries. One often overlooked problem with compilation, however, is the time it takes to generate machine code. Even with fast compilation frameworks like L…
View article: Query Processing and Optimization in Modern Database Systems
Query Processing and Optimization in Modern Database Systems Open
This thesis focuses on the challenges for database systems posed by modern hardware. We present a concurrent transaction processing system and show how to synchronize data structures efficiently. We further design a parallel query engine f…