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DOI: 10.4230/LIPIcs.ICDT.2017.4

GYM: A Multiround Distributed Join Algorithm

Authors: Foto N. Afrati, Manas R. Joglekar, Christopher M. Re, Semih Salihoglu, and Jeffrey D. Ullman

Published in: LIPIcs, Volume 68, 20th International Conference on Database Theory (ICDT 2017)

Abstract

Multiround algorithms are now commonly used in distributed data processing systems, yet the extent to which algorithms can benefit from running more rounds is not well understood. This paper answers this question for several rounds for the problem of computing the equijoin of n relations. Given any query Q with width w, intersection width iw, input size IN, output size OUT, and a cluster of machines with M=\Omega(IN \frac{1}{\epsilon}) memory available per machine, where \epsilon > 1 and w \ge 1 are constants, we show that: 1. Q can be computed in O(n) rounds with O(n(INw + OUT)2/M) communication cost with high probability. Q can be computed in O(log(n)) rounds with O(n(INmax(w, 3iw) + OUT)2/M) communication cost with high probability. Intersection width is a new notion we introduce for queries and generalized hypertree decompositions (GHDs) of queries that captures how connected the adjacent components of the GHDs are. We achieve our first result by introducing a distributed and generalized version of Yannakakis's algorithm, called GYM. GYM takes as input any GHD of Q with width w and depth d, and computes Q in O(d + log(n)) rounds and O(n (INw + OUT)2/M) communication cost. We achieve our second result by showing how to construct GHDs of Q with width max(w, 3iw) and depth O(log(n)). We describe another technique to construct GHDs with longer widths and lower depths, demonstrating other tradeoffs one can make between communication and the number of rounds.

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Foto N. Afrati, Manas R. Joglekar, Christopher M. Re, Semih Salihoglu, and Jeffrey D. Ullman. GYM: A Multiround Distributed Join Algorithm. In 20th International Conference on Database Theory (ICDT 2017). Leibniz International Proceedings in Informatics (LIPIcs), Volume 68, pp. 4:1-4:18, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2017)

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@InProceedings{afrati_et_al:LIPIcs.ICDT.2017.4,
  author =	{Afrati, Foto N. and Joglekar, Manas R. and Re, Christopher M. and Salihoglu, Semih and Ullman, Jeffrey D.},
  title =	{{GYM: A Multiround Distributed Join Algorithm}},
  booktitle =	{20th International Conference on Database Theory (ICDT 2017)},
  pages =	{4:1--4:18},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-024-8},
  ISSN =	{1868-8969},
  year =	{2017},
  volume =	{68},
  editor =	{Benedikt, Michael and Orsi, Giorgio},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ICDT.2017.4},
  URN =		{urn:nbn:de:0030-drops-70462},
  doi =		{10.4230/LIPIcs.ICDT.2017.4},
  annote =	{Keywords: Joins, Yannakakis, Bulk Synchronous Processing, GHDs}
}

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DOI: 10.4230/LIPIcs.ICDT.2016.1

The ICDT 2016 Test of Time Award Announcement

Authors: Foto N. Afrati, Claire David, and Georg Gottlob

Published in: LIPIcs, Volume 48, 19th International Conference on Database Theory (ICDT 2016)

Abstract

We describe the 2016 ICDT Test of Time Award which is awarded to Chandra Chekuri and Anand Rajaraman for their 1997 ICDT paper on "Conjunctive Query Containment Revisited".

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Foto N. Afrati, Claire David, and Georg Gottlob. The ICDT 2016 Test of Time Award Announcement. In 19th International Conference on Database Theory (ICDT 2016). Leibniz International Proceedings in Informatics (LIPIcs), Volume 48, pp. 1:1-1:2, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2016)

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@InProceedings{afrati_et_al:LIPIcs.ICDT.2016.1,
  author =	{Afrati, Foto N. and David, Claire and Gottlob, Georg},
  title =	{{The ICDT 2016 Test of Time Award Announcement}},
  booktitle =	{19th International Conference on Database Theory (ICDT 2016)},
  pages =	{1:1--1:2},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-002-6},
  ISSN =	{1868-8969},
  year =	{2016},
  volume =	{48},
  editor =	{Martens, Wim and Zeume, Thomas},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ICDT.2016.1},
  URN =		{urn:nbn:de:0030-drops-57938},
  doi =		{10.4230/LIPIcs.ICDT.2016.1},
  annote =	{Keywords: conjunctive query, treewidth, NP-hardness, rewriting}
}

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GYM: A Multiround Distributed Join Algorithm

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The ICDT 2016 Test of Time Award Announcement

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