Hai Lan

Hai Lan


Research Focus & Metrics

Academic Career Length

21Years (2006-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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13 June 2023 in Proceedings of the ACM on Management of Data
Verified
Journal Article
Open access
HLHai Lan
Hai Lan
ZBZhifeng Bao
Zhifeng Bao
JCJ. Shane Culpepper
J. Shane Culpepper
RBRenata Borovica-Gajic
Renata Borovica-Gajic
Although many updatable learned indexes have been proposed in recent years, whether they can outperform traditional approaches on disk remains unknown. In this study, we revisit and implement four state-of-the-art updatable learned indexes on disk, and compare them against the B+-tree under a wide range of settings. Through our evaluation, we make some key observations: 1) Overall, the B+-tree performs well across a range of workload types and datasets. 2) A learned index could outperform B+-tree or other learned indexes on disk for a specific workload. For example, PGM achieves the best performance in write-only workloads while LIPP significantly outperforms others in lookup-only workloads. We further conduct a detailed performance analysis to reveal the strengths and weaknesses of these learned indexes on disk. Moreover, we summarize the observed common shortcomings in five categories and propose four design principles to guide future design of on-disk, updatable learned indexes: (1) reducing the index's tree height, (2) better data structures to lower operation overheads, (3) improving the efficiency of scan operations, and (4) more efficient storage layout.

1 June 2006
Verified
Conference Paper
Closed access
HLHong-Da Liu
Hong-Da Liu
ZMZhong-Li Ma
Zhong-Li Ma
SHENG LIUSHENG LIU
SHENG LIU
HLHai Lan
Hai Lan
This paper introduces a kind of immune genetic algorithm which regards objective function as antigen, solution as antibody and updates the population using evolutionary strategy. After economic emission load dispatch which belongs to multi-objective constrained optimization problems is discussed, main processes of immune genetic algorithm to solve this matter is given. Through tests a power system model with five coal-burning generating units, feasibility and validity of this algorithm is proved. And by comparing with genetic algorithm and Hopfield neural network, optimization and quick constringency of this algorithm to solve similar problems are proved

19 January 2026 in The VLDB Journal
Verified
Journal Article
Open access
PDF file
FLFeng Luo
Feng Luo
HLHai Lan
Hai Lan
Hui LuoHui Luo
Hui Luo
ZBZhifeng Bao
Zhifeng Bao
JCJ. Shane Culpepper
J. Shane Culpepper
XWXiaoli Wang
Xiaoli Wang
Missing values in tabular data lakes can severely impact data analysis and diminish the performance in downstream applications. We highlight that a robust imputation strategy should properly take three aspects of variety into consideration: source of imputed value, the types of tables involved, and the data types of the missing value. Existing imputation methods rely on estimation-based approaches (using a model trained on data from the same table to estimate missing values) or search-based approaches (retrieving values from other tables). Unfortunately, none of these approaches effectively incorporate all three aspects of variety. To address this gap, we propose , a novel framework that uses a C ombination of E stimation-based and S earch-based methods for missing value I mputation in D ata lakes. contains three core modules: (1) the , which efficiently discovers candidate values from tables by exploiting the contextual information; (2) the , which introduces an influence function and a sampling-based exploration strategy to yield accurate estimated values; (3) the , which determines the most suitable method based on table-level and column-level statistics. Extensive experiments conducted on three data lakes demonstrate that effectively and efficiently addresses the missing value problem.

18 May 2026 in Proceedings of the ACM on Management of Data
Verified
Journal Article
Open access
HLHai Lan
Hai Lan
TWTingting Wang
Tingting Wang
ZBZhifeng Bao
Zhifeng Bao
Guoliang LiGuoliang Li
Guoliang Li
DJDaomin Ji
Daomin Ji
GHGang Hua
Gang Hua
Managing the rapidly growing scholarly corpus poses significant challenges in representation, reasoning, and efficient analysis. An ideal system should unify structured knowledge management, agentic planning, and interpretable execution to support diverse scholarly queries – from retrieval to knowledge discovery and generation – at scale. Unfortunately, existing RAG and document analytics systems fail to achieve all query types simultaneously. To this end, we propose AgenticScholar, an agentic scholarly data management system that integrates a structure-aware knowledge representation layer, an LLM-centric hybrid query planning layer, and a unified execution layer with composable operators. AgenticScholar autonomously translates natural language queries into executable DAG plans, enabling end-to-end reasoning over multi-modal scholarly data. Extensive experiments demonstrate that AgenticScholar significantly outperforms existing systems in effectiveness, efficiency, and interpretability, offering a practical foundation for future research on agentic scholarly data management.

7 November 2023
Verified
Book Chapter
Closed access
PDF file
HLHai Lan
Hai Lan
YZYuanjia Zhang
Yuanjia Zhang
YDYu Dong
Yu Dong
DHDongxu Huang
Dongxu Huang
LTLiu Tang
Liu Tang
JZJian Zhang
Jian Zhang

11 December 2025 in arXiv
Verified
Preprint
Open access
PDF file
GLGuanli Liu
Guanli Liu
RBRenata Borovica-Gajic
Renata Borovica-Gajic
HLHai Lan
Hai Lan
ZBZhifeng Bao
Zhifeng Bao
Reinforcement learning has recently been used to enhance index structures, giving rise to reinforcement learning-enhanced spatial indices (RLESIs) that aim to improve query efficiency during index construction. However, their practical benefits remain unclear due to the lack of unified implementations and comprehensive evaluations, especially in disk-based settings. We present the first modular and extensible benchmark for RLESIs. Built on top of an existing spatial index library, our framework decouples index training from building, supports parameter tuning, and enables consistent comparison with traditional, advanced, and learned spatial indices. We evaluate 12 representative spatial indices across six datasets and diverse workloads, including point, range, kNN, spatial join, and mixed read/write queries. Using latency, I/O, and index statistics as metrics, we find that while RLESIs can reduce query latency with tuning, they consistently underperform learned spatial indices and advanced variants in both query efficiency and index build cost. These findings highlight that although RLESIs offer promising architectural compatibility, their high tuning costs and limited generalization hinder practical adoption.