Recent work on semi-structured data has revitalized the interest in path queries, i.e., queries that ask for all pairs of objects in the database that are connected by a path conforming to a certain specification, in particular to a regular expression. Also, in semi-structured data, as well as in da
Regular Path Queries with Constraints
β Scribed by Serge Abiteboul; Victor Vianu
- Publisher
- Elsevier Science
- Year
- 1999
- Tongue
- English
- Weight
- 310 KB
- Volume
- 58
- Category
- Article
- ISSN
- 0022-0000
No coin nor oath required. For personal study only.
β¦ Synopsis
The evaluation of path expression queries on semistructured data in a distributed asynchronous environment is considered. The focus is on the use of local information expressed in the form of path constraints in the optimization of path expression queries. In particular, decidability and complexity results on the implication problem for path constraints are established.
π SIMILAR VOLUMES
Rewriting queries using views is a powerful technique that has applications in query optimization, data integration, data warehousing, etc. Query rewriting in relational databases is by now rather well investigated. However, in the framework of semistructured data the problem of rewriting has receiv
## Abstract XML documents combine features from classical IR systems allowing free text, with explicit structures as in databases. Many query languages have been specially designed for IR applications on XML documents. This work concentrates on a special type of language for which the problem of pr
RDF is a knowledge representation language dedicated to the annotation of resources within the framework of the semantic web. Among the query languages for RDF, SPARQL allows querying RDF through graph patterns, i.e., RDF graphs involving variables. Other languages, inspired by the work in databases
We study a new version of the shortest path problem. Let G Γ (V, E) be a directed graph. Each arc e β E has two numbers attached to it: a transit time b(e, u) and a cost c(e, u), which are functions of the departure time u at the beginning vertex of the arc. Moreover, postponement of departure (i.e.