We study the problem of answering conjunctive queries with free access patterns under updates. A free access pattern is a partition of the free variables of the query into input and output. The query returns tuples over the output variables given a tuple of values over the input variables. We introduce a fully dynamic evaluation approach for such queries. We also give a syntactic characterisation of those queries that admit constant time per single-tuple update and whose output tuples can be enumerated with constant delay given an input tuple. Finally, we chart the complexity trade-off between the preprocessing time, update time and enumeration delay for such queries. For a class of queries, our approach achieves optimal, albeit non-constant, update time and delay. Their optimality is predicated on the Online Matrix-Vector Multiplication conjecture. Our results recover prior work on the dynamic evaluation of conjunctive queries without access patterns.
@InProceedings{kara_et_al:LIPIcs.ICDT.2023.17, author = {Kara, Ahmet and Nikolic, Milos and Olteanu, Dan and Zhang, Haozhe}, title = {{Conjunctive Queries with Free Access Patterns Under Updates}}, booktitle = {26th International Conference on Database Theory (ICDT 2023)}, pages = {17:1--17:20}, series = {Leibniz International Proceedings in Informatics (LIPIcs)}, ISBN = {978-3-95977-270-9}, ISSN = {1868-8969}, year = {2023}, volume = {255}, editor = {Geerts, Floris and Vandevoort, Brecht}, publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik}, address = {Dagstuhl, Germany}, URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ICDT.2023.17}, URN = {urn:nbn:de:0030-drops-177599}, doi = {10.4230/LIPIcs.ICDT.2023.17}, annote = {Keywords: fully dynamic algorithm, enumeration delay, complexity trade-off, dichotomy} }
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