As part of research by members of the Department of Computer Science at the University of Georgia, we have developed a Java-based Transaction Manager that fits into the multi-layered design of MMODB, a main-memory database system. We have sought to maximize the benefits of the Java programming language and to implement transaction principles that are suitable for in-memory databases. In this pa...

The memory system is a fundamental performance and energy bottleneck in almost all computing systems. Recent system design, application, and technology trends that require more capacity, bandwidth, efficiency, and predictability out of the memory system make it an even more important system bottleneck. At the same time, DRAM technology is experiencing difficult technology scaling challenges tha...

Truong, T. 2016. Main-Memory Query Processing Utilizing External Indexes. Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology 1352. 45 pp. Uppsala: Acta Universitatis Upsaliensis. ISBN 978-91-554-9509-1. Many applications require storage and indexing of new kinds of data in main-memory, e.g. color histograms, textures, shape features, gene sequenc...

Existing datacube precomputation schemes materialize selected datacube tuples on disk, choosing the most beneficial cuboids (i.e., combinations of dimensions) to materialize given a space limit. However, in the context of a data-warehouse receiving frequent “append” updates to the database, the cost of keeping these disk-resident cuboids up-to-date can be high. In this paper, we propose a main ...

We present the PPOST-architecture (Persistent Parallel Object Store) for main-memory database systems on parallel computers, that is suited for applications with challenging performance requirements. The architecture takes full advantage of parallelism, large main memories and fast switching networks. An important property of this architecture is its excellent scaling behavior.

We present the first algorithm that performs the LZ78 compression of a text of length n over alphabet [1..σ], whose output is z integers, using only O(z lg σ) bits of main memory. The algorithm reads the input text from disk in a single pass, and writes the compressed output to disk. The text can also be decompressed within the same main memory usage, which is unprecedented too. The algorithm i...

In this paper we use the trace driven simulation to study the performance of the main memory. We discuss the eeect of using interleaved memory with fast page mode or precharge mode to improve the memory performance. A method that combines both fast page mode and precharge mode is deened. This method proves to give the best memory performance for memory banks having low or high order address int...

In this paper, the performance and characteristics of the execution of various join-trees on a parallel DBMS are studied. The results of this study, are a step into the direction of the design of a query optimization strategy that is t for parallel execution of complex queries. Among others, synchronization issues are identiied to limit the performance gain from parallelism. A new hash-join alg...

Locking is widely used as a concurrency control mechanism in database systems. As more OLTP databases are stored mostly or entirely in memory, transactional throughput is less and less limited by disk IO, and lock managers increasingly become performance bottlenecks. In this paper, we introduce very lightweight locking (VLL), an alternative approach to pessimistic concurrency control for main-m...

The main memory system is a critical component of modern computer systems. Dynamic Random Access Memory (DRAM) based memory designs dominate the industry due to mature device technology and low cost. These designs, however, face several challenges moving forward. These challenges arise due to legacy DRAM device design choices, advances in Central Processing Unit (CPU) design, and the demand for...