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: h0d4ed76c499ebca0
Venue: SIGMOD
Year: 2026
Pagerank: 4.9793485e-05
Overall Rank: 10,656 | 28.36%
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
40	The Case for Learned Index Structures	2018	SIGMOD	0.00046284649
56	M-tree: An Efficient Access Method for Similarity Search in Metric Spaces	1997	VLDB	0.00040370171
264	A Class of Data Structures for Associative Searching	1984	PODS	0.00022757762
430	ALEX: An Updatable Adaptive Learned Index	2020	SIGMOD	0.00018409112
597	Distance-Based Indexing For High-Dimensional Metric Spaces	1997	SIGMOD	0.00015766567
779	FITing-Tree: A Data-aware Index Structure	2019	SIGMOD	0.00014030069
802	Near Neighbor Search in Large Metric Spaces	1995	VLDB	0.00013847746
868	Learning Multi-dimensional Indexes	2020	SIGMOD	0.00013354403
1,132	Qd-tree: Learning Data Layouts for Big Data Analytics	2020	SIGMOD	0.00011898257
1,191	Tsunami: A Learned Multi-dimensional Index for Correlated Data and Skewed Workloads	2021	VLDB	0.00011590153
1,446	LISA: A Learned Index Structure for Spatial Data	2020	SIGMOD	0.00010629222
1,878	Effectively Learning Spatial Indices	2020	VLDB	9.4451309e-05
3,803	CARMI: A Cache-Aware Learned Index with a Cost-based Construction Algorithm	2022	VLDB	7.0127652e-05
4,639	Pivot-based Metric Indexing	2017	VLDB	6.4903275e-05
4,850	The RLR-Tree: A Reinforcement Learning Based R-Tree for Spatial Data	2023	SIGMOD	6.3808017e-05
8,196	WISK: A Workload-aware Learned Index for Spatial Keyword Queries	2023	SIGMOD	5.3794981e-05
9,919	Waffle: In-memory Grid Index for Moving Objects with Reinforcement Learning-based Configuration Tuning System	2022	VLDB	5.1103839e-05

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#	Overall Rank	Paper	Year	Venue
1	7,030	Efficient Similarity Join and Search on Multi-Attribute Data	2015	SIGMOD
2	7,856	Similarity Search on Bregman Divergence: Towards Non-Metric Indexing	2009	VLDB
3	597	Distance-Based Indexing For High-Dimensional Metric Spaces	1997	SIGMOD
4	6,973	A Scalable Index for Top-k Subtree Similarity Queries	2019	SIGMOD
5	9,741	LES3: Learning-based Exact Set Similarity Search	2021	VLDB
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7	7,395	LiteHST: A Tree Embedding based Method for Similarity Search	2023	SIGMOD
8	9,400	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	4,639	Pivot-based Metric Indexing	2017	VLDB