Links' Seminars and Public Events | ![]() ![]() |
Fri, September 30, 2016 all day | arrivée de Jose Lozano |
Thu, September 29, 2016 2:00 pm 4:00 pm | Seminar Links by Aurélien Lemay "Lille-Salle B21" |
Tue, September 27, 2016 all day | Ircica fetes ces 10 ans Lille |
Fri, September 9, 2016 2:00 pm 4:00 pm | Momar Sakho "Lille-Salle B21" |
Wed, September 7, 2016 11:00 am 12:00 pm | jason demagoj |
Wed, August 31, 2016 10:00 am 1:00 pm | Links Seminar by Domagoj Vrgoč: "Querying Graph with Data" "Lille-Salle B21" |
Thu, July 28, 2016 all day | Visit of Serge Abiteboul and Victor Vianu |
Mon, July 11, 2016 to Tue, July 12, 2016 all day | Aggreg meeting Marseille |
Mon, June 27, 2016 all day | Colis ANR project: general meeting Inria Paris, Salle 119 "Ada Lovelace" |
Fri, June 24, 2016 2:00 pm 4:00 pm | Fatima Belkouch: on the hypercube algorithm for conjunctive queries Abstract: We consider the problem of computing a conjunctive query on a large database in a parallel setting with p servers. Unlike traditional query processing, the complexity is no longer dominated by the number of disk accesses. Typically, a query is evaluated by a sufficiently large number of servers such that the entire data can be kept in the main memory of these servers. The dominant cost becomes that of communicating data and synchronizing among the servers. I will present some interesting results in [1, 2, 3, 4] dealing with the communication complexity of massively parallel computation of a query. The computation is performed in "rounds". First, I will present the Massively Parallel Communication (MPC) model to analyze the tradeoff between the number of rounds and the amount of communication required in a massively parallel computing environment. Then I will present the HyperCube (HC) algorithm that computes a full conjunctive query q in one round. I will discuss the communication complexity [2]. The main result is the optimal load O(m/p1/τ ) where τ is the fractional vertex cover of the hypergraph of q and m the input data size. References [1] Parallel Evaluation of Conjunctive Queries. Paris Koutris, Dan Suciu PODS2011 [2] Communication Steps for Parallel Query Processing. Paul Beame, Paris Koutris, Dan Suciu PODS2013 [3] Skew in Parallel Query Processing. Paul Beame, Paris Koutris Dan Suciu PODS'2014 [4] Worst-Case Optimal Algorithms for Parallel Query Processing. Paris Koutris, Paul Beame, Dan Suciu ICDT2016 "Lille-Salle B11" |