Query Processing under GLAV Mappings for Relational and Graph Databases. Calvanese, D., Giacomo, De, G., Lenzerini, M., & Vardi, M. Y. PVLDB, 6(2):61-72, 2012. Paper Link abstract bibtex Schema mappings establish a correspondence between data stored in two databases, called source and target respectively. Query processing under schema mappings has been investigated extensively in the two cases where each target atom is mapped to a query over the source (called GAV, global-as-view), and where each source atom is mapped to a query over the target (called LAV, local-as-view). The general case, called GLAV, in which queries over the source are mapped to queries over the target, has attracted a lot of attention recently, especially for data exchange. However, query processing for GLAV mappings has been considered only for the basic service of query answering, and mainly in the context of conjunctive queries (CQs) in relational databases. In this paper we study query processing for GLAV mappings in a wider sense, considering not only query answering, but also query rewriting, perfectness (the property of a rewriting to compute exactly the certain answers), and query containment relative to a mapping. We deal both with the relational case, and with graph databases, where the basic querying mechanism is that of regular path queries. Query answering in GLAV can be smoothly reduced to a combination of the LAV and GAV cases, and for CQs this reduction can be exploited also for the remaining query processing tasks. In contrast, as we show, GLAV query processing for graph databases is non-trivial and requires new insights and techniques. We obtain upper bounds for answering, rewriting, and perfectness, and show decidability of relative containment.
@article{ journals/pvldb/CalvaneseGLV12,
abstract = {Schema mappings establish a correspondence between data stored in two databases, called source and target respectively.
Query processing under schema mappings has been investigated extensively in the two cases where each target
atom is mapped to a query over the source (called GAV,
global-as-view), and where each source atom is mapped to
a query over the target (called LAV, local-as-view). The
general case, called GLAV, in which queries over the source
are mapped to queries over the target, has attracted a lot
of attention recently, especially for data exchange. However, query processing for GLAV mappings has been considered only for the basic
service of query answering, and
mainly in the context of conjunctive queries (CQs) in relational databases. In this paper we study query processing
for GLAV mappings in a wider sense, considering not only
query answering, but also query rewriting, perfectness (the
property of a rewriting to compute exactly the certain answers), and query containment relative to a mapping. We
deal both with the relational case, and with graph databases,
where the basic querying mechanism is that of regular path
queries. Query answering in GLAV can be smoothly reduced
to a combination of the LAV and GAV cases, and for CQs
this reduction can be exploited also for the remaining query
processing tasks. In contrast, as we show, GLAV query processing for graph databases is non-trivial and requires new
insights and techniques. We obtain upper bounds for answering, rewriting, and perfectness, and show decidability
of relative containment.},
added-at = {2014-06-02T12:19:53.000+0200},
audience = {academic},
author = {Calvanese, Diego and Giacomo, Giuseppe De and Lenzerini, Maurizio and Vardi, Moshe Y.},
biburl = {http://www.bibsonomy.org/bibtex/23b78ae3e9e447ac8e9f27d215fb1333e/savo.fabio},
ee = {http://www.vldb.org/pvldb/vol6/p61-calvanese.pdf},
interhash = {68bf115699be6cfcd2059cb5fc3dd13c},
intrahash = {3b78ae3e9e447ac8e9f27d215fb1333e},
journal = {PVLDB},
keywords = {optique-project},
number = {2},
pages = {61-72},
partneroptique = {UNIROMA1, FUB},
title = {Query Processing under GLAV Mappings for Relational and Graph Databases.},
url = {http://dblp.uni-trier.de/db/journals/pvldb/pvldb6.html#CalvaneseGLV12},
volume = {6},
wpoptique = {WP4},
year = {2012},
yearoptique = {Y1}
}
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The\r\ngeneral case, called GLAV, in which queries over the source\r\nare mapped to queries over the target, has attracted a lot\r\nof attention recently, especially for data exchange. However, query processing for GLAV mappings has been considered only for the basic \r\nservice of query answering, and\r\nmainly in the context of conjunctive queries (CQs) in relational databases. In this paper we study query processing\r\nfor GLAV mappings in a wider sense, considering not only\r\nquery answering, but also query rewriting, perfectness (the\r\nproperty of a rewriting to compute exactly the certain answers), and query containment relative to a mapping. We\r\ndeal both with the relational case, and with graph databases,\r\nwhere the basic querying mechanism is that of regular path\r\nqueries. Query answering in GLAV can be smoothly reduced\r\nto a combination of the LAV and GAV cases, and for CQs\r\nthis reduction can be exploited also for the remaining query\r\nprocessing tasks. 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We deal both with the relational case, and with graph databases, where the basic querying mechanism is that of regular path queries. Query answering in GLAV can be smoothly reduced to a combination of the LAV and GAV cases, and for CQs this reduction can be exploited also for the remaining query processing tasks. In contrast, as we show, GLAV query processing for graph databases is non-trivial and requires new insights and techniques. We obtain upper bounds for answering, rewriting, and perfectness, and show decidability of relative containment."},"bibtype":"article","biburl":"http://www.bibsonomy.org/bib/search/optique-project?bibtex.entriesPerPage=10000","downloads":0,"keywords":["optique-project"],"search_terms":["query","processing","under","glav","mappings","relational","graph","databases","calvanese","giacomo","de","lenzerini","vardi"],"title":"Query Processing under GLAV Mappings for Relational and Graph Databases.","year":2012,"dataSources":["tYYCZGwzkJatkJPTa"]}