License: Creative Commons Attribution 4.0 International license (CC BY 4.0)
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DOI: 10.4230/LIPIcs.ICDT.2021.19
URN: urn:nbn:de:0030-drops-137277
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Casel, Katrin ; Schmid, Markus L.

Fine-Grained Complexity of Regular Path Queries

LIPIcs-ICDT-2021-19.pdf (0.9 MB)


A regular path query (RPQ) is a regular expression q that returns all node pairs (u, v) from a graph database that are connected by an arbitrary path labelled with a word from L(q). The obvious algorithmic approach to RPQ evaluation (called PG-approach), i. e., constructing the product graph between an NFA for q and the graph database, is appealing due to its simplicity and also leads to efficient algorithms. However, it is unclear whether the PG-approach is optimal. We address this question by thoroughly investigating which upper complexity bounds can be achieved by the PG-approach, and we complement these with conditional lower bounds (in the sense of the fine-grained complexity framework). A special focus is put on enumeration and delay bounds, as well as the data complexity perspective. A main insight is that we can achieve optimal (or near optimal) algorithms with the PG-approach, but the delay for enumeration is rather high (linear in the database). We explore three successful approaches towards enumeration with sub-linear delay: super-linear preprocessing, approximations of the solution sets, and restricted classes of RPQs.

BibTeX - Entry

  author =	{Casel, Katrin and Schmid, Markus L.},
  title =	{{Fine-Grained Complexity of Regular Path Queries}},
  booktitle =	{24th International Conference on Database Theory (ICDT 2021)},
  pages =	{19:1--19:20},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-179-5},
  ISSN =	{1868-8969},
  year =	{2021},
  volume =	{186},
  editor =	{Yi, Ke and Wei, Zhewei},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{},
  URN =		{urn:nbn:de:0030-drops-137277},
  doi =		{10.4230/LIPIcs.ICDT.2021.19},
  annote =	{Keywords: Graph Databases, Regular Path Queries, Enumeration, Fine-Grained Complexity}

Keywords: Graph Databases, Regular Path Queries, Enumeration, Fine-Grained Complexity
Collection: 24th International Conference on Database Theory (ICDT 2021)
Issue Date: 2021
Date of publication: 11.03.2021

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