You are here

Events

Monday, November 19, 2018 — 10:30 AM EST

A. Erdem Sarıyüce, University at Buffalo

Abstract: Finding dense substructures in a network is a fundamental graph mining operation, with applications in bioinformatics, social networks, and visualization to name a few. Yet most standard formulations of this problem (like clique, quasi-clique, densest at-least-k subgraph) are NP-hard. Furthermore, the goal is rarely to find the “true optimum” but to identify many (if not all) dense substructures, understand their distribution in the graph, and ideally determine relationships among them. In this talk, I will talk about a framework that we designed to find dense regions of the graph with hierarchical relations.

Wednesday, November 21, 2018 — 12:15 PM EST

Hemant Saxena, PhD candidate
David R. Cheriton School of Computer Science

We address the problem of discovering dependencies from distributed big data.  Existing (non-distributed) algorithms focus on minimizing computation by pruning the search space of possible dependencies.  However, distributed algorithms must also optimize data communication costs, especially in current shared-nothing settings.  To do this, we define a set of primitives for dependency discovery, which corresponds to data processing steps separated by communication barriers, and we present efficient implementations that optimize both computation and communication costs.  Using real data, we show that algorithms built using our primitives are significantly faster and more communication-efficient than straightforward distributed implementations.

Wednesday, November 28, 2018 — 12:15 PM EST

Jaemyung Kim, PhD candidate
David R. Cheriton School of Computer Science

Transaction durability guarantees the ability to recover committed transactions from failures. However, making every transaction durable impacts transaction processing performance. Some ad-hoc durability mechanisms (e.g., delayed durability) improve performance, but they risk transactions losing their effects due to failures. The current one-size-fits-all transaction durability model does not solve this problem. We propose a new generalized transaction durability model to trade-off performance and durability and argue that transactions should also provide flexible durability like they provide multiple isolation levels. We evaluate the performance of a modified PostgreSQL that supports the new durability model using a micro-benchmark to show the durability/performance trade-offs.

Monday, December 10, 2018 — 10:30 AM EST

Panos K. Chrysanthis, University of Pittsburgh

Abstract: Online analytics, in most advanced scientific, business, and defense applications, rely heavily on the efficient execution of large numbers of Aggregate Continuous Queries (ACQs). ACQs continuously aggregate streaming data and periodically produce results such as max or average over a given window of the latest data.  It was shown that in processing ACQs it is beneficial to use incremental evaluation, which involves storing and reusing calculations performed over the unchanged parts of the window, rather than performing the re-evaluation of the entire window after each update.

Monday, January 14, 2019 — 10:48 AM EST

Speaker: Verena Kantere, University of Ottawa

S M T W T F S
28
29
30
31
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
1
  1. 2019 (1)
    1. January (1)
  2. 2018 (24)
    1. December (1)
    2. November (4)
    3. October (3)
    4. September (2)
    5. July (3)
    6. June (1)
    7. May (3)
    8. April (3)
    9. March (3)
    10. January (1)
  3. 2017 (15)
    1. December (1)
    2. November (1)
    3. October (1)
    4. September (3)
    5. August (1)
    6. July (1)
    7. May (1)
    8. April (1)
    9. March (2)
    10. February (1)
    11. January (2)
  4. 2016 (25)
  5. 2015 (19)
  6. 2014 (34)

Public talks of interest to the Data Systems Group are posted here, and are also mailed to the dsg-faculty, dsg-grads, dsg-friends mailing lists. Subscribe to one of these mailing lists to receive e-mail notification of upcoming events. Everyone is welcome to attend.