Tractable Orders for Direct Access to Ranked Answers of Conjunctive Queries
Summary: Identifies when self-join-free CQs admit quasilinear preprocessing plus O(log n) direct access to the k-th answer: provides a decidable characterization for lexicographic orderings and shows sum-of-weights orders are tractable only in trivial cases. For the selection variant (single-position), gives a quasilinear algorithm for a subclass of full CQs using Frederickson–Johnson selection on sorted matrices and proves matching hardness for the rest. (summarized by gpt-5-mini on Feb 09 2026)
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Authors
- 1. Nofar Carmeli (Technion)
- 2. Nikolaos Tziavelis (Northeastern University)
- 3. Wolfgang Gatterbauer (Northeastern University)
- 4. Benny Kimelfeld (Technion)
- 5. Mirek Riedewald (Northeastern University)
BibTeX Citation
@inproceedings{carmeli_pods21,
address = {New York, NY, USA},
series = {{PODS} '21},
title = {{Tractable Orders for Direct Access to Ranked Answers of Conjunctive Queries}},
url = {https://dl.acm.org/doi/10.1145/3452021.3458331},
doi = {10.1145/3452021.3458331},
booktitle = {Proceedings of the {ACM} {SIGMOD} Symposium on {Principles} of {Database} {Systems}},
publisher = {Association for Computing Machinery},
author = {Carmeli, Nofar and Tziavelis, Nikolaos and Gatterbauer, Wolfgang and Kimelfeld, Benny and Riedewald, Mirek},
year = {2021}
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Citations counted here include only citations to other VLDB/SIGMOD/CIDR/PODS papers in this database.
| Rank | Cited Paper | Year | Venue | Pagerank |
|---|---|---|---|---|
| 814 | Hypertree Decompositions: Questions and Answers | 2016 | PODS | 0.00013841737 |
| 2,745 | Optimal Algorithms for Ranked Enumeration of Answers to Full Conjunctive Queries | 2020 | VLDB | 8.1747954e-05 |
| 2,777 | Answering (Unions of) Conjunctive Queries using Random Access and Random-Order Enumeration | 2020 | PODS | 8.1352657e-05 |
| 3,991 | The Complexity of Resilience and Responsibility for Self-Join-Free Conjunctive Queries | 2016 | VLDB | 6.9695922e-05 |
| 5,225 | Approximate Lifted Inference with Probabilistic Databases | 2015 | VLDB | 6.310093e-05 |
| 5,601 | Optimal Join Algorithms Meet Top-k | 2020 | SIGMOD | 6.1540123e-05 |
| 5,905 | A Dichotomy in the Complexity of Deletion Propagation with Functional Dependencies | 2012 | PODS | 6.0461963e-05 |
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