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AMW
2011
13 years 2 months ago
Subqueries in SPARQL
Subqueries are a poweful feature which allows to enforce reuse, composition, rewriting and optimization in a query language. In this paper we perform a comprehensive study of the i...
Renzo Angles, Claudio Gutierrez
MTA
2007
141views more  MTA 2007»
13 years 10 months ago
Flexible integration of multimedia sub-queries with qualitative preferences
Complex multimedia queries, aiming to retrieve from large databases those objects that best match the query specification, are usually processed by splitting them into a set of m ...
Ilaria Bartolini, Paolo Ciaccia, Vincent Oria, M. ...
VLDB
2005
ACM
122views Database» more  VLDB 2005»
14 years 4 months ago
Optimizing Nested Queries with Parameter Sort Orders
Nested iteration is an important technique for query evaluation. It is the default way of executing nested subqueries in SQL. Although decorrelation often results in cheaper non-n...
Ravindra Guravannavar, H. S. Ramanujam, S. Sudarsh...
SIGMOD
2000
ACM
161views Database» more  SIGMOD 2000»
14 years 3 months ago
Answering Complex SQL Queries Using Automatic Summary Tables
We investigate the problem of using materialized views to answer SQL queries. We focus on modern decision-support queries, which involve joins, arithmetic operations and other (po...
Markos Zaharioudakis, Roberta Cochrane, George Lap...
SSDBM
2007
IEEE
121views Database» more  SSDBM 2007»
14 years 5 months ago
Cost-based Optimization of Complex Scientific Queries
High energy physics scientists analyze large amounts of data looking for interesting events when particles collide. These analyses are easily expressed using complex queries that ...
Ruslan Fomkin, Tore Risch