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DOI: 10.4230/LIPIcs.ICDT.2023.7

Constant-Delay Enumeration for SLP-Compressed Documents

Authors: Martín Muñoz and Cristian Riveros

Published in: LIPIcs, Volume 255, 26th International Conference on Database Theory (ICDT 2023)

Abstract

We study the problem of enumerating results from a query over a compressed document. The model we use for compression are straight-line programs (SLPs), which are defined by a context-free grammar that produces a single string. For our queries we use a model called Annotated Automata, an extension of regular automata that allows annotations on letters. This model extends the notion of Regular Spanners as it allows arbitrarily long outputs. Our main result is an algorithm which evaluates such a query by enumerating all results with output-linear delay after a preprocessing phase which takes linear time on the size of the SLP, and cubic time over the size of the automaton. This is an improvement over Schmid and Schweikardt’s result [Markus L. Schmid and Nicole Schweikardt, 2021], which, with the same preprocessing time, enumerates with a delay which is logarithmic on the size of the uncompressed document. We achieve this through a persistent data structure named Enumerable Compact Sets with Shifts which guarantees output-linear delay under certain restrictions. These results imply constant-delay enumeration algorithms in the context of regular spanners. Further, we use an extension of annotated automata which utilizes succinctly encoded annotations to save an exponential factor from previous results that dealt with constant-delay enumeration over vset automata. Lastly, we extend our results in the same fashion Schmid and Schweikardt did [Markus L. Schmid and Nicole Schweikardt, 2022] to allow complex document editing while maintaining the constant-delay guarantee.

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Martín Muñoz and Cristian Riveros. Constant-Delay Enumeration for SLP-Compressed Documents. In 26th International Conference on Database Theory (ICDT 2023). Leibniz International Proceedings in Informatics (LIPIcs), Volume 255, pp. 7:1-7:17, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2023)

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@InProceedings{munoz_et_al:LIPIcs.ICDT.2023.7,
  author =	{Mu\~{n}oz, Mart{\'\i}n and Riveros, Cristian},
  title =	{{Constant-Delay Enumeration for SLP-Compressed Documents}},
  booktitle =	{26th International Conference on Database Theory (ICDT 2023)},
  pages =	{7:1--7:17},
  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.2023.7},
  URN =		{urn:nbn:de:0030-drops-177495},
  doi =		{10.4230/LIPIcs.ICDT.2023.7},
  annote =	{Keywords: SLP compression, query evaluation, enumeration algorithms}
}

Document

DOI: 10.4230/LIPIcs.ICDT.2022.19

Streaming Enumeration on Nested Documents

Authors: Martín Muñoz and Cristian Riveros

Published in: LIPIcs, Volume 220, 25th International Conference on Database Theory (ICDT 2022)

Abstract

Some of the most relevant document schemas used online, such as XML and JSON, have a nested format. In the last decade, the task of extracting data from nested documents over streams has become especially relevant. We focus on the streaming evaluation of queries with outputs of varied sizes over nested documents. We model queries of this kind as Visibly Pushdown Transducers (VPT), a computational model that extends visibly pushdown automata with outputs and has the same expressive power as MSO over nested documents. Since processing a document through a VPT can generate a massive number of results, we are interested in reading the input in a streaming fashion and enumerating the outputs one after another as efficiently as possible, namely, with constant-delay. This paper presents an algorithm that enumerates these elements with constant-delay after processing the document stream in a single pass. Furthermore, we show that this algorithm is worst-case optimal in terms of update-time per symbol and memory usage.

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Martín Muñoz and Cristian Riveros. Streaming Enumeration on Nested Documents. In 25th International Conference on Database Theory (ICDT 2022). Leibniz International Proceedings in Informatics (LIPIcs), Volume 220, pp. 19:1-19:18, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)

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@InProceedings{munoz_et_al:LIPIcs.ICDT.2022.19,
  author =	{Mu\~{n}oz, Mart{\'\i}n and Riveros, Cristian},
  title =	{{Streaming Enumeration on Nested Documents}},
  booktitle =	{25th International Conference on Database Theory (ICDT 2022)},
  pages =	{19:1--19:18},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-223-5},
  ISSN =	{1868-8969},
  year =	{2022},
  volume =	{220},
  editor =	{Olteanu, Dan and Vortmeier, Nils},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ICDT.2022.19},
  URN =		{urn:nbn:de:0030-drops-158935},
  doi =		{10.4230/LIPIcs.ICDT.2022.19},
  annote =	{Keywords: Streaming, nested documents, query evaluation, enumeration algorithms}
}

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Constant-Delay Enumeration for SLP-Compressed Documents

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Streaming Enumeration on Nested Documents

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