LM-Tree: A Hybrid Learned Index for Similarity Search in Metric Spaces

Summary: Hybrid learned M-Tree for metric-space similarity search: each node adaptively chooses pivots and a lightweight model to boost pruning, avoiding the weak single-pivot vs costly multi-pivot tradeoff. Efficient maintenance supports updates via pivot/model re-optimization, splits, and merges with low overhead. (summarized by gpt-5-mini on Apr 11 2026)

Paper ID: 7682
Venue: SIGMOD
Year: 2026
Pagerank: 5.093636e-05
Overall Rank: 10,469 | 28.18%
DOI: 10.1145/3786665

Incoming Non-self Citations Over Time

No non-self incoming citations found for this paper in this database.

Authors

1. Yaqi Wang (Northeastern University)
2. Bin Wang (Northeastern University)
3. Rui Zhu (Shenyang Aerospace University)
4. Wenli Sun (Northeastern University)
5. Xiaochun Yang (Northeastern University)

BibTeX Citation

@inproceedings{wang_sigmod26,
        title = {{LM-Tree: A Hybrid Learned Index for Similarity Search in Metric Spaces}},
        author = {Wang, Yaqi and Wang, Bin and Zhu, Rui and Sun, Wenli and Yang, Xiaochun},
        series = {{SIGMOD} '26},
        booktitle = {Proceedings of the {ACM} {SIGMOD} International Conference on Management of Data},
        publisher = {Association for Computing Machinery},
        doi = {10.1145/3786665},
        url = {https://dl.acm.org/doi/10.1145/3786665},
        year = {2026}
}

Incoming Citations (Sorted by Pagerank)

Showing 0 of 0 citing papers.

Rank	Citing Paper	Year	Venue	Pagerank

Outgoing Citations (Sorted by Pagerank)

Showing 17 of 17 cited papers.

Citations counted here include only citations to other VLDB/SIGMOD/CIDR/PODS papers in this database.

Rank	Cited Paper	Year	Venue	Pagerank
43	The Case for Learned Index Structures	2018	SIGMOD	0.00046060254
56	M-tree: An Efficient Access Method for Similarity Search in Metric Spaces	1997	VLDB	0.00040719947
253	A Class of Data Structures for Associative Searching	1984	PODS	0.00023200431
447	ALEX: An Updatable Adaptive Learned Index	2020	SIGMOD	0.00018322593
592	Distance-Based Indexing For High-Dimensional Metric Spaces	1997	SIGMOD	0.00016029789
784	Near Neighbor Search in Large Metric Spaces	1995	VLDB	0.00014069958
790	FITing-Tree: A Data-aware Index Structure	2019	SIGMOD	0.0001401445
873	Learning Multi-dimensional Indexes	2020	SIGMOD	0.00013481915
1,135	Qd-tree: Learning Data Layouts for Big Data Analytics	2020	SIGMOD	0.00012032847
1,174	Tsunami: A Learned Multi-dimensional Index for Correlated Data and Skewed Workloads	2021	VLDB	0.00011817414
1,418	LISA: A Learned Index Structure for Spatial Data	2020	SIGMOD	0.00010835539
1,840	Effectively Learning Spatial Indices	2020	VLDB	9.6404567e-05
3,729	CARMI: A Cache-Aware Learned Index with a Cost-based Construction Algorithm	2022	VLDB	7.1683974e-05
4,627	Pivot-based Metric Indexing	2017	VLDB	6.5963674e-05
4,751	The RLR-Tree: A Reinforcement Learning Based R-Tree for Spatial Data	2023	SIGMOD	6.5241784e-05
8,048	WISK: A Workload-aware Learned Index for Spatial Keyword Queries	2023	SIGMOD	5.5003171e-05
9,739	Waffle: In-memory Grid Index for Moving Objects with Reinforcement Learning-based Configuration Tuning System	2022	VLDB	5.227679e-05

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#	Overall Rank	Paper	Year	Venue
1	6,906	Efficient Similarity Join and Search on Multi-Attribute Data	2015	SIGMOD
2	7,708	Similarity Search on Bregman Divergence: Towards Non-Metric Indexing	2009	VLDB
3	592	Distance-Based Indexing For High-Dimensional Metric Spaces	1997	SIGMOD
4	6,832	A Scalable Index for Top-k Subtree Similarity Queries	2019	SIGMOD
5	11,702	LES3: Learning-based Exact Set Similarity Search	2021	VLDB
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7	7,376	LiteHST: A Tree Embedding based Method for Similarity Search	2023	SIGMOD
8	9,334	Adaptive Indexing in High-Dimensional Metric Spaces	2023	VLDB
9	56	M-tree: An Efficient Access Method for Similarity Search in Metric Spaces	1997	VLDB
10	4,627	Pivot-based Metric Indexing	2017	VLDB