Filters








782 Hits in 6.7 sec

On Acyclic Conjunctive Queries and Constant Delay Enumeration [chapter]

Guillaume Bagan, Arnaud Durand, Etienne Grandjean
Lecture Notes in Computer Science  
We then introduce a large subclass of acyclic formulas called CCQ = and prove that the tuples of a CCQ = query can be enumerated with a linear time precomputation and a constant delay between consecutive  ...  CCQ = or it cannot be enumerated with linear precomputation and constant delay.  ...  conjunctive query (with or without disequalities) which is simple 3 either is free-connex acyclic or cannot be enumerated with linear precomputation and constant delay.  ... 
doi:10.1007/978-3-540-74915-8_18 fatcat:fhnld2yxxzdh3pi3qlllopljru

Constant Delay Enumeration for Conjunctive Queries

Luc Segoufin
2015 SIGMOD record  
We focus on the case where the enumeration is performed with a constant delay between any two consecutive solutions, after a linear time preprocessing. This cannot be always achieved.  ...  It requires restricting either the class of queries or the class of databases. We consider conjunctive queries and describe several scenarios when this is possible.  ...  For acyclic conjunctive queries linear delay enumeration can be obtained with no restriction on the databases. Theorem 6. [5] .  ... 
doi:10.1145/2783888.2783894 fatcat:vpya5xdg4vgzhfzockebesoqdy

Conjunctive queries with self-joins, towards a fine-grained complexity analysis [article]

Nofar Carmeli, Luc Segoufin
2022 arXiv   pre-print
Moreover, free-connex acyclic queries can be enumerated with constant delay. In the presence of self-joins, the situation is not that clear.  ...  The complexity of evaluating conjunctive queries without self-joins is well understood: Acyclicity is the boundary for being able to test whether there is a solution in linear time, and free-connexity  ...  Acknowledgements We acknowledge numerous discussions with Louis Jachiet and thank him for his valuable input.  ... 
arXiv:2206.04988v1 fatcat:bbgvwww2dnfsrfisnnmvm73efe

A glimpse on constant delay enumeration (Invited Talk)

Luc Segoufin, Marc Herbstritt
2014 Symposium on Theoretical Aspects of Computer Science  
We focus on the case where the enumeration is performed with a constant delay between any two consecutive solutions, after a linear time preprocessing. This cannot be always achieved.  ...  We survey some of the recent results about enumerating the answers to queries over a database.  ...  For acyclic conjunctive queries linear delay enumeration can be obtained with no restriction on the structures. ◮ Theorem 13. [4] .  ... 
doi:10.4230/lipics.stacs.2014.13 dblp:conf/stacs/Segoufin14 fatcat:yi6xqnceejdzxaof667rw6q2r4

Enumerating with constant delay the answers to a query

Luc Segoufin
2013 Proceedings of the 16th International Conference on Database Theory - ICDT '13  
We survey recent results about enumerating with constant delay the answers to a query over a database.  ...  one by one with constant time between any consecutive outputs.  ...  Acknowledgment: We are grateful to Cristina Sirangelo, Arnaud Durand, Wojtek Kazana and Yann Strozecki for their valuable comments on earlier version of this paper.  ... 
doi:10.1145/2448496.2448498 dblp:conf/icdt/Segoufin13 fatcat:knkcl5pm2vebjfc5o6erez3yuu

First-Order Queries over One Unary Function [chapter]

Arnaud Durand, Frédéric Olive
2006 Lecture Notes in Computer Science  
linear in the size of the structure followed by an enumeration of all solutions (i.e. the tuples that satisfy the formula) with a constant delay (i.e. depending on the formula size only) between each solution  ...  Finally, we investigate the special case of conjunctive queries over quasiunary structures and show that their combined complexity is not prohibitive, even from a dynamical (enumeration) point of view.  ...  We denote by Constant-Delay the class of query problems which are enumerable with constant delay.  ... 
doi:10.1007/11874683_22 fatcat:pmwb5lv75reinppoc455yxl3pe

Enumeration in Data Management (Dagstuhl Seminar 19211)

Endre Boros, Benny Kimelfeld, Reinhard Pichler, Nicole Schweikardt, Michael Wagner
2019 Dagstuhl Reports  
This report documents the program and the outcomes of Dagstuhl Seminar 19211 "Enumeration in Data Management".  ...  In addition, we aimed to build and disseminate a toolkit for data-centric enumeration problems, including algorithmic techniques, proof techniques, and important indicator problems.  ...  A Circuit-Based Approach to Efficient Enumeration: Enumerating MSO Query Results on Trees and Words Constant-Delay Enumeration applied to Dynamic Query Processing: The Dynamic Yannakakis Algorithm Stijn  ... 
doi:10.4230/dagrep.9.5.89 dblp:journals/dagstuhl-reports/BorosKPS19 fatcat:gfir76niqfhmno2hpj563cwwqe

Constant Delay Enumeration with FPT-Preprocessing for Conjunctive Queries of Bounded Submodular Width

Christoph Berkholz, Nicole Schweikardt, Michael Wagner
2019 International Symposium on Mathematical Foundations of Computer Science  
time we can build a data structure that allows to enumerate, without repetition and with constant delay, all tuples of the query result.  ...  ACM 2013) introduced the notion of submodular width of a conjunctive query (CQ) and showed that for any class Φ of Boolean CQs of bounded submodular width, the model-checking problem for Φ on the class  ...  complexity of conjunctive queries and have shown that every class of conjunctive queries of bounded free-connex submodular width admits constant delay enumeration with FPT-preprocessing.  ... 
doi:10.4230/lipics.mfcs.2019.58 dblp:conf/mfcs/BerkholzS19 fatcat:mymzb4fe7zapla6aa7wwn3726a

Conjunctive queries with inequalities under updates

Muhammad Idris, Martín Ugarte, Stijn Vansummeren, Hannes Voigt, Wolfgang Lehner
2018 Proceedings of the VLDB Endowment  
enumerate the full query output, as well as the changes produced under single updates.  ...  PVLDB Reference Format: Muhammad Idris, Martin Ugarte, Stijn Vansummeren, Hannes Voigt and Wolfgang Lehner. Conjunctive Queries with Inequalities Under Updates. PVLDB, 11(7): 733-745, 2018.  ...  optimal for two classes of queries (q-hierarchical and free-connex acyclic conjunctive queries).  ... 
doi:10.14778/3192965.3192966 fatcat:lnbqt2y6hfcbdflcbs37q4ynde

Efficient Enumeration for Conjunctive Queries over X-underbar Structures [chapter]

Guillaume Bagan, Arnaud Durand, Emmanuel Filiot, Olivier Gauwin
2010 Lecture Notes in Computer Science  
Then, we consider acyclic conjunctive queries and show that such queries admit an enumeration algorithm with delay O(|Q| · |D|) and a preprocessing in O(|Q| · |S|) where D is the domain of S.  ...  We propose efficient enumeration procedures for acyclic and general conjunctive queries whose delay is exponential in ℓ but polynomial (even quasi-linear) in |Q| and |S|.  ...  Enumeration of acyclic conjunctive queries has been studied in [4] .  ... 
doi:10.1007/978-3-642-15205-4_10 fatcat:jpeof6wlezfhjebsbfqoswdbaq

Efficiently Enumerating Answers to Ontology-Mediated Queries

Carsten Lutz, Marcin Przybylko
2022 Proceedings of the 41st ACM SIGMOD-SIGACT-SIGAI Symposium on Principles of Database Systems  
Our main result is that enumeration of the traditional complete answers and of both kinds of partial answers is possible with linear-time preprocessing and constant delay for OMQs that are both acyclic  ...  We study the enumeration of answers to ontology-mediated queries (OMQs) where the ontology is a set of guarded TGDs or formulated in the description logic ELI and the query is a conjunctive query (CQ).  ...  This model is standard in the context of constant delay enumeration, see [4, 10, 20, 35] and the long version for more details. Modes of Query Evaluation.  ... 
doi:10.1145/3517804.3524166 fatcat:5bzuh5zoxzcwjcliqtkk6fvkmi

Enumeration Algorithms for Conjunctive Queries with Projection [article]

Shaleen Deep, Xiao Hu, Paraschos Koutris
2021 arXiv   pre-print
We investigate the enumeration of query results for an important subset of CQs with projections, namely star and path queries.  ...  We also present new results involving tradeoff between preprocessing time and delay guarantees for enumeration of path queries that contain projections.  ...  Acyclicity itself is necessary for having constant delay enumeration: A conjunctive query admits constant delay enumeration after linear-time preprocessing if and only if it is free-connex acyclic [BB13  ... 
arXiv:2101.03712v3 fatcat:gbdhv5djxjcaxexqazwsifxr7u

Enumerating Answers to Ontology-Mediated Queries: Partial Answers and Efficiency (Extended Abstract)

Carsten Lutz, Marcin Przybylko
2021 International Workshop on Description Logics  
Note that there is no restriction on how the running time of the preprocessing or how the delay depends on the OMQ Q.  ...  This corresponds to data complexity in singletesting where Q is fixed and thus of constant size. An excellent recent survey of the work on answer enumeration in database theory is [5] .  ...  This abstract reports about the forthcoming article [14] where we consider guarded TGDs G and the description logic ELI as the ontology language and conjunctive queries (CQs) as the query language.  ... 
dblp:conf/dlog/LutzP21 fatcat:7zbyvdpspjfofmzub5imiywxwi

The Dynamic Yannakakis Algorithm

Muhammad Idris, Martin Ugarte, Stijn Vansummeren
2017 Proceedings of the 2017 ACM International Conference on Management of Data - SIGMOD '17  
Instead of the materialization of results, we require a data structure that allows: (1) linear time maintenance under updates, (2) constant-delay enumeration of the output, (3) constant-time lookups in  ...  Moreover, we identify a sub-class of queries for which Dyn features constant-time update per tuple and show that this class is maximal.  ...  In this paper, therefore, we are concerned with designing a practical algorithm for dynamic query evaluation based on constant-delay enumeration.  ... 
doi:10.1145/3035918.3064027 dblp:conf/sigmod/IdrisUV17 fatcat:m266vplaj5ezzgy6nyzam7a6pa

Trade-offs in Static and Dynamic Evaluation of Hierarchical Queries

Ahmet Kara, Milos Nikolic, Dan Olteanu, Haozhe Zhang
2020 Proceedings of the 39th ACM SIGMOD-SIGACT-SIGAI Symposium on Principles of Database Systems  
), acyclic conjunctive queries that are not free-connex cannot be enumerated with constant delay after linear preprocessing time [9] .  ...  For the strict subclass of free-connex acyclic queries called q-hierarchical, maintenance can be achieved with linear-time preprocessing and constant-time update and enumeration delay [11, 26] .  ...  Acyclicity itself is necessary for having constant delay enumeration: A conjunctive query admits constant delay enumeration after linear-time preprocessing if and only if it is free-connex acyclic [15  ... 
doi:10.1145/3375395.3387646 dblp:conf/pods/0002NOZ20 fatcat:rkthvcehl5d2rnbg62hwgtbnta
« Previous Showing results 1 — 15 out of 782 results