Enumerating with constant delay the answers to a query

@inproceedings{Segoufin2013EnumeratingWC,
  title={Enumerating with constant delay the answers to a query},
  author={Luc Segoufin},
  booktitle={International Conference on Database Theory},
  year={2013},
  url={https://api.semanticscholar.org/CorpusID:16412681}
}
The case when enumeration can be achieved with a preprocessing running in time linear in the size of the database, followed by an enumeration process outputting the answers one by one with constant time between any consecutive outputs is focused on.
View on ACM
hal.inria.fr
60 Citations
Highly Influential Citations
9
Background Citations
28
Methods Citations
16

60 Citations

Constant Delay Enumeration for Conjunctive Queries

This work focuses on the case where the enumeration is performed with a constant delay between any two consecutive solutions, after a linear time preprocessing, about enumerating the answers to queries over a database.

A glimpse on constant delay enumeration

Several scenarios when the enumeration of the answers to queries over a database is performed with a constant delay between any two consecutive solutions, after a linear time preprocessing are described.

A glimpse on constant delay enumeration (Invited Talk)

This work focuses on the case where the enumeration is performed with a constant delay between any two consecutive solutions, after a linear time preprocessing, where this cannot be always achieved.

Answering Conjunctive Queries under Updates

A new notion of q-hierarchical conjunctive queries is exhibited and it is shown that these can be maintained efficiently in the following sense: during a linear time pre-processing phase, a data structure is built that enables constant delay enumeration of the query results; and when the database is updated, the data structure can be updated and restart the enumeration phase within constant time.

Query evaluation with constant delay

This thesis is concentrated around the problem of query evaluation and proposes a particular solution to this problem: a scenario where in stead of just computing, the authors are interested in enumerating q(D) with constant delay.

MSO queries on trees: enumerating answers under updates

The algorithms and complexity results in the paper are presented in terms of node-selecting automata representing the MSO queries, and an algorithm that uses an O(n) preprocessing phase and enumerates answers with O(log n) delay between them is exhibited.

Ranked Enumeration of Conjunctive Query Results

The notions of {\em decomposable} and {\em compatible} (w.r.t. a query decomposition) ranking functions are introduced, which allow for partial aggregation of tuple scores in order to efficiently enumerate the output.

On the Complexity of Enumerating the Answers to Well-Designed Pattern Trees

This work embarkes on a systematic study of the complexity of the enumeration problem of wdPTs and identifies several tractable and intractable cases of this problem both from a classical complexity point of view and from a parameterized complexity points of view.

General Space-Time Tradeoffs via Relational Queries

The key insight in this work is to exploit the formalism of relational algebra by casting the problems as answering join queries over a relational database by proposing a unified framework that captures several widely studied algorithmic problems.

MSO Queries on Trees: Enumerating Answers under Updates Using Forest Algebras

An exemplary application of the framework for maintaining forest algebra representations that are of logarithmic height for unranked trees to the problem of efficiently enumerating answers to MSO-definable queries over trees which are subject to local updates is provided.
...

47 References

Tractable Counting of the Answers to Conjunctive Queries

Enumeration Complexity of Logical Query Problems with Second-order Variables

By considering the number of alternations in the quantifier prefixes of formulas, it is shown that query problems defined by first order formulas with free first order and second order variables either admit a constant delay or a polynomial delay enumeration algorithm or are hard to enumerate.

Enumeration of first-order queries on classes of structures with bounded expansion

It is shown that answers to first-order queries can be enumerated with constant delay after a linear time preprocessing and that counting the number of answers to a query can be done in time linear in the size of the database.

First-order query evaluation on structures of bounded degree

A different proof of this result based on Gaifman's locality theorem for first-order logic is given, showing that the constants obtained yield a total evaluation time that is triply exponential in the size of the input formula, matching the complexity of the best known evaluation algorithms.

On Acyclic Conjunctive Queries and Constant Delay Enumeration

The enumeration complexity of the natural extension of acyclic conjunctive queries with disequalities is studied and it is shown that for each query of free-connex treewidth bounded by some constant k, enumeration of results can be done with O(|M|k+1) precomputation steps and constant delay.

Enumeration of monadic second-order queries on trees

A different proof of this result based on the deterministic factorization forest decomposition theorem of Colcombet [2007], which shows that the enumeration problem of Monadic Second-Order queries with first-order free variables over trees is in CONSTANT-DELAYlin.

On the complexity of database queries (extended abstract)

It is shown that, if the query size (or the number of variables in the query) is considered as a parameter, then the relational calculus and its fragments are classified at appropriate levels of the so-called W hierarchy of Downey and Fellows.

Linear delay enumeration and monadic second-order logic

Efficient Enumeration for Conjunctive Queries over X-underbar Structures

It is shown that query evaluation is NP-hard and, unless P = NP, these queries do not admit enumeration algorithms with a combined polynomial time delay, but it is also shown that hardness relies only on the number l of variables that appear in inequalities.

On Polynomials Defined by Acyclic Conjunctive Queries and Weighted Counting Problems

It is proved that summing the weights of solutions of quantifier-free $\ACQ$ queries can be done in polynomial time, and a new parameter for quantified queries is introduced that permits to isolate large island of tractability.