Revisiting answering tree pattern queries using views
Author(s)
Wang, Junhu
Yu, Jeffrey Xu
Griffith University Author(s)
Year published
2012
Metadata
Show full item recordAbstract
We revisit the problem of answering tree pattern queries using views.We first show that, for queries and views
that do not have nodes labeled with the wildcard *, there is an approach which does not require us to find any
rewritings explicitly, yet which produces the same answers as the maximal contained rewriting. Then, using
the new approach, we give simple conditions and a corresponding algorithm for identifying redundant view
answers, which are view answers that can be ignored when evaluating the maximal contained rewriting.We
also consider redundant view answers in the case where there are multiple views, the relationship ...
View more >We revisit the problem of answering tree pattern queries using views.We first show that, for queries and views that do not have nodes labeled with the wildcard *, there is an approach which does not require us to find any rewritings explicitly, yet which produces the same answers as the maximal contained rewriting. Then, using the new approach, we give simple conditions and a corresponding algorithm for identifying redundant view answers, which are view answers that can be ignored when evaluating the maximal contained rewriting.We also consider redundant view answers in the case where there are multiple views, the relationship between redundant views and redundant view answers, and discuss how to combine the removal of redundant view answers and redundant rewritings. We show that the aforesaid results can be extended to a number of other special cases. Finally, for arbitrary queries and views in P{/,//,∗,[]}, we provide a method to find the maximal contained rewriting and show how to answer the query using views without explicitly finding the rewritings.
View less >
View more >We revisit the problem of answering tree pattern queries using views.We first show that, for queries and views that do not have nodes labeled with the wildcard *, there is an approach which does not require us to find any rewritings explicitly, yet which produces the same answers as the maximal contained rewriting. Then, using the new approach, we give simple conditions and a corresponding algorithm for identifying redundant view answers, which are view answers that can be ignored when evaluating the maximal contained rewriting.We also consider redundant view answers in the case where there are multiple views, the relationship between redundant views and redundant view answers, and discuss how to combine the removal of redundant view answers and redundant rewritings. We show that the aforesaid results can be extended to a number of other special cases. Finally, for arbitrary queries and views in P{/,//,∗,[]}, we provide a method to find the maximal contained rewriting and show how to answer the query using views without explicitly finding the rewritings.
View less >
Journal Title
ACM Transactions on Database Systems
Volume
37
Issue
3
Subject
Data management and data science
Information systems
Database systems