Concept

Conjunctive query

Related publications (16)

Parallel-Correctness and Containment for Conjunctive Queries with Union and Negation

Single-round multiway join algorithms first reshuffle data over many servers and then evaluate the query at hand in a parallel and communication-free way. A key question is whether a given distribution policy for the reshuffle is adequate for computing a g ...

ASSOC COMPUTING MACHINERY2019

RAQ: Relationship-Aware Graph Querying in Large Networks

Akhil Arora, Arnab Bhattacharya

The phenomenal growth of graph data from a wide variety of real-world applications has rendered graph querying to be a problem of paramount importance. Traditional techniques use structural as well as node similarities to find matches of a given query grap ...

ASSOC COMPUTING MACHINERY2019

Interactive Visual Exploration of Spatio-Temporal Urban Data Sets using Urbane

Anastasia Ailamaki, Eleni Tzirita Zacharatou, Haoqiong Bian

The recent explosion in the number and size of spatio-temporal data sets from urban environments and social sensors creates new opportunities for data-driven approaches to understand and improve cities. Visual analytics systems like Urbane aim to empower d ...

2018

Parallelizing Query Optimization on Shared-Nothing Architectures

Christoph Koch, Immanuel Trummer

Data processing systems offer an ever increasing degree of parallelism on the levels of cores, CPUs, and processing nodes. Query optimization must exploit high degrees of parallelism in order not to gradually become the bottleneck of query evaluation. We s ...

Assoc Computing Machinery2016

Efficient Incremental Data Analysis

Milos Nikolic

Many data-intensive applications require real-time analytics over streaming data. In a growing number of domains -- sensor network monitoring, social web applications, clickstream analysis, high-frequency algorithmic trading, and fraud detections to name a ...

EPFL2016

Fast Queries Over Heterogeneous Data Through Engine Customization

Anastasia Ailamaki, Ioannis Alagiannis, Manolis Karpathiotakis

Industry and academia are continuously becoming more data-driven and data-intensive, relying on the analysis of a wide variety of heterogeneous datasets to gain insights. The different data models and formats pose a significant challenge on performing anal ...

Assoc Computing Machinery2016

A Query Model to Capture Event Pattern Matching in RDF Stream Processing Query Languages

Jean Paul Calbimonte Perez

The current state of the art in RDF Stream Processing (RSP) proposes several models and implementations to combine Semantic Web technologies with Data Stream Management System (DSMS) operators like windows. Meanwhile, only a few solutions combine Semantic ...

Springer Int Publishing Ag2016

Smooth Scan: Statistics-Oblivious Access Paths

Anastasia Ailamaki, Renata Borovica-Gajic

Query optimizers depend heavily on statistics representing column distributions to create efficient query plans. In many cases, though, statistics are outdated or non-existent, and the process of refreshing statistics is very expensive, especially for ad-h ...

2015

Synthesizing Java Expressions from Free-Form Queries

Viktor Kuncak, Tihomir Gvero

We present a new code assistance tool for integrated development environments. Our system accepts as input free-form queries containing a mixture of English and Java, and produces Java code expressions that take the query into account and respect syntax, t ...

Assoc Computing Machinery2015

Solid-State Storage and Work Sharing for Efficient Scaleup Data Analytics

Manoussos Gavriil Athanassoulis

Today, managing, storing and analyzing data continuously in order to gain additional insight is becoming commonplace. Data analytics engines have been traditionally optimized for read-only queries assuming that the main data reside on mechanical disks. The ...

EPFL2014

Efficient Processing of Ranking Queries in Novel Applications

Parisa Haghani

Ranking queries, which return only a subset of results matching a user query, have been studied extensively in the past decade due to their importance in a wide range of applications. In this thesis, we study ranking queries in novel environments and setti ...

EPFL2010

Generalized Hypertree Decompositions: NP-hardness and Tractable Variants

Zoltán Miklós

The generalized hypertree width GHW(H) of a hypergraph H is a measure of its cyclicity. Classes of conjunctive queries or constraint satisfaction problems whose associated hypergraphs have bounded GHW are known to be solvable in polynomial time. However, i ...

2009

A Scalable, Predictable Join Operator for Highly Concurrent Data Warehouses

George Candea

Conventional data warehouses employ the query-at-a-time model, which maps each query to a distinct physical plan. When several queries execute concurrently, this model introduces contention, because the physical plans—unaware of each other—compete for acce ...

2009

Contextualized and personalized location-based services

Shijun Yu

Advances in the technologies of smart mobile devices and tiny sensors together with the increase in the number of web resources open up a plethora of new mobile information services where people can acquire and disseminate information at any place and any ...

EPFL2008

Sharing of probabilistically correlated data in peer-to-peer networks

Roman Schmidt

The impact of Peer-to-Peer (P2P) networks on the Internet landscape is undisputed. It has led to a series of new applications, e.g., as part of the so-called Web 2.0. The shift from the classical client-server based paradigm of the Internet, with a clear d ...

EPFL2008

Distributed Cache Table: Efficient Query-Driven Processing of Multi-Term Queries in P2P Networks

Karl Aberer, Gleb Skobeltsyn

The state-of-the-art techniques for processing multi-term queries in P2P environments are query flooding and inverted list intersection. However, it has been shown that due to scalability reasons both methods fail to support full-text search in large scale ...

2006