Database Research Group Events

• Ashraf will talk about trendy topics in social networks based on the paper: Structural Trend Analysis For Online Social Networks Ceren Budak, Divyakant Agrawal, Amr El Abbadi.
• Gunes will talk about database cracking based on the paper "Merging What's Cracked, Cracking What's Merged: Adaptive Indexing in Main-Memory Column-Stores" by Stratos Idreos (CWI), Stefan Manegold (CWI), Harumi Kuno (HP Labs), Goetz Graefe (HP Labs).
• Khuzaima will talk about something.
• Dave will talk about a scheme for optimistic concurrency control allowing highly-parallel updates to tree-structured indexes: Optimistic Concurrency Control by Melding Trees Philip A. Bernstein (Microsoft Research), Colin W. Reid (Microsoft), Ming Wu (Microsoft Research), Xinhao Yuan (Tsinghua University)
• Patrick will talk about something.
• Ken will talk about something so secret that nobody else at VLDB heard about it.
• Ning will talk about graph databases.

In the first part of this talk, we will address the problem of high false positive error rate of signature files by introducing COCA Filters, a new variation of Bloom Filters which exploits the co-occurrence probability of words in documents to reduce the false positive error. We will show that by using this technique we can reduce the false positive error by up to 21 times, for the same index size.

In the second part of the talk, we will address the long query execution time of signature files by proposing a scalable approach that utilizes the massive computational power of Graphics Processing Units (GPUs) to accelerate the query execution. The impressive speed-up and the scalability of our proposed method will be shown experimentally. The scalability of this approach allows us to reach the desirable speed-up by increasing the number of GPUs.

The first part of the talk is based on a paper entitled "COCA Filters: Co-Occurrence Aware Bloom Filters", a joint work with Kamran Tirdad, Ian Munro and Alejandro Lopez-Ortiz. This Paper won the best student paper award in SPIRE 2011.

I will first look at Hadoop MapReduce queries. These queries are written using arbitrary Java code, which makes them difficult to anaylse and optimise. By analyzing certain queries With symbolic execution, we can extract input restrictions from them, significantly improving their performance.

Secondly, I will look at database queries in Java 8. When Java 8 is released next year, it will finally include limited support for functional programming. I will show how this functional support can be combined with symbolic execution to allow programmers to finally write database queries in a functional-style, like in Microsoft's LINQ.

I will be discussing a paper which describes different cloud pricing models and analyzes their sensitivity to workload type and distribution, and proposes a pricing model that reduces these sensitivities. "Resource and Virtualization Costs up in the Cloud: Models and Design Choices." Daniel Gmach, Jerry Rolia, Ludmila Cherkasova (HP Labs). In Proc. 2011 IEEE/IFIP 41st Conf. on Dependable Systems & Networks, Hong Kong, p395-402.