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Shaofeng Cai

dblp:228/6099 · DBLP profile ↗
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29ranked-venue papers
3as first author
23since 2021 · last 2026
0000-0001-8605-076XORCID · verified

Domains — the database's venue-derived domains; a paper can count in several

Databases, data management, data science and information retrieval · 18 · 2 first-author · 13 since 2021Artificial intelligence and machine learning · 8 · 7 since 2021Graphics, computer vision, multimedia, augmented reality and games · 4 · 1 first-author · 4 since 2021Applied, interdisciplinary, general and emerging computing · 1 · 1 since 2021

Expertise — from the expertise taxonomy: the topics of the expert's papers under the CCF categories. A weight counts papers with recency: 1 for a paper about the topic, 0.3 when the topic is its context, halved every five years.

Databases, data mining, and information retrieval
11 papers
Data mining · 37% Machine learning and data management · 20% Data stream processing · 14%
Artificial intelligence
15 papers
Deep learning architectures and training · 31% Time series and sequential data · 20% Trustworthy machine learning · 19%
Interdisciplinary, comprehensive, and emerging computing
5 papers
Medical and health informatics · 75% Smart cities and intelligent transportation · 22% Computational finance and economics · 3%
Network and information security
2 papers
Network security · 60% Privacy and data protection · 40%
Computer networks
1 paper
Cellular and mobile networks · 50% Edge and fog computing · 25% Network management and operations · 25%

Topics — the 30 heaviest of 54, each with the papers that count most for it

TopicWeightPapersLastEvidence papers
Data stream processing › evolving data › concept drift
concept drift adaptation
2.532026
Catching Every Ripple: Enhanced Anomaly Awareness via Dynamic Concept Adaptation · IEEE Trans. Pattern Anal. Mach. Intell. 2026
In-Context Adaptation to Concept Drift for Learned Database Operations · ICML 2025
METER: A Dynamic Concept Adaptation Framework for Online Anomaly Detection · Proc. VLDB Endow. 2023
Data mining
anomaly detection
2.432026
Catching Every Ripple: Enhanced Anomaly Awareness via Dynamic Concept Adaptation · IEEE Trans. Pattern Anal. Mach. Intell. 2026
VecAug: Unveiling Camouflaged Frauds with Cohort Augmentation for Enhanced Detection · KDD 2024
METER: A Dynamic Concept Adaptation Framework for Online Anomaly Detection · Proc. VLDB Endow. 2023
Machine learning › Deep learning architectures and training
regularization
2.042023
Regularized Pairwise Relationship based Analytics for Structured Data · Proc. ACM Manag. Data 2023
Improving Data Analytics with Fast and Adaptive Regularization · IEEE Trans. Knowl. Data Eng. 2021
Adaptive Knowledge Driven Regularization for Deep Neural Networks · AAAI 2021
Machine learning and data management
learned database components
1.932025
In-Context Adaptation to Concept Drift for Learned Database Operations · ICML 2025
Database Native Model Selection: Harnessing Deep Neural Networks in Database Systems · Proc. VLDB Endow. 2024
NeurDB: an AI-powered autonomous data system · Sci. China Inf. Sci. 2024
Data mining › anomaly detection
streaming anomaly detection
1.722026
Catching Every Ripple: Enhanced Anomaly Awareness via Dynamic Concept Adaptation · IEEE Trans. Pattern Anal. Mach. Intell. 2026
METER: A Dynamic Concept Adaptation Framework for Online Anomaly Detection · Proc. VLDB Endow. 2023
Machine learning › Deep learning architectures and training › regularization
adaptive regularization
1.332021
Improving Data Analytics with Fast and Adaptive Regularization · IEEE Trans. Knowl. Data Eng. 2021
Adaptive Knowledge Driven Regularization for Deep Neural Networks · AAAI 2021
Adaptive Lightweight Regularization Tool for Complex Analytics · ICDE 2018
Medical and health informatics
clinical data analysis
1.232022
DyHealth: Making Neural Networks Dynamic for Effective Healthcare Analytics · Proc. VLDB Endow. 2022
TRACER: A Framework for Facilitating Accurate and Interpretable Analytics for High Stakes Applications · SIGMOD Conference 2020
Improving Data Analytics with Fast and Adaptive Regularization · IEEE Trans. Knowl. Data Eng. 2021
Machine learning › Efficient and distributed learning › automated machine learning
neural architecture search
1.022022
NASI: Label- and Data-agnostic Neural Architecture Search at Initialization · ICLR 2022
Understanding Architectures Learnt by Cell-based Neural Architecture Search · ICLR 2020
Machine learning › Trustworthy machine learning
interpretability
0.922021
ARM-Net: Adaptive Relation Modeling Network for Structured Data · SIGMOD Conference 2021
TRACER: A Framework for Facilitating Accurate and Interpretable Analytics for High Stakes Applications · SIGMOD Conference 2020
Machine learning › Trustworthy machine learning
neural network interpretability
0.912025
Investigating Pattern Neurons in Urban Time Series Forecasting · ICLR 2025
Medical and health informatics
electronic health records
0.912025
NeuralCohort: Cohort-aware Neural Representation Learning for Healthcare Analytics · ICML 2025
Indexing and storage engines › vector index
approximate nearest neighbor index
0.912025
HAKES: Scalable Vector Database for Embedding Search Service · Proc. VLDB Endow. 2025
Query processing and optimization
cardinality estimation
0.912025
In-Context Adaptation to Concept Drift for Learned Database Operations · ICML 2025
Indexing and storage engines
vector database
0.912025
HAKES: Scalable Vector Database for Embedding Search Service · Proc. VLDB Endow. 2025
Indexing and storage engines
vector index
0.912025
HAKES: Scalable Vector Database for Embedding Search Service · Proc. VLDB Endow. 2025
Machine learning › Time series and sequential data › anomaly detection
anomaly segmentation
0.812024
Do LLMs Understand Visual Anomalies? Uncovering LLM's Capabilities in Zero-shot Anomaly Detection · ACM Multimedia 2024
Computer vision › Vision and language › vision-language model › prompt learning
vision-language model prompting
0.812024
Do LLMs Understand Visual Anomalies? Uncovering LLM's Capabilities in Zero-shot Anomaly Detection · ACM Multimedia 2024
Machine learning › Time series and sequential data › anomaly detection
visual anomaly detection
0.812024
Do LLMs Understand Visual Anomalies? Uncovering LLM's Capabilities in Zero-shot Anomaly Detection · ACM Multimedia 2024
Machine learning › Time series and sequential data › anomaly detection
zero-shot anomaly detection
0.812024
Do LLMs Understand Visual Anomalies? Uncovering LLM's Capabilities in Zero-shot Anomaly Detection · ACM Multimedia 2024
Data mining › feature engineering
automated feature engineering
0.812024
CtxPipe: Context-aware Data Preparation Pipeline Construction for Machine Learning · Proc. ACM Manag. Data 2024
Machine learning and data management
data management for machine learning
0.812024
Database Native Model Selection: Harnessing Deep Neural Networks in Database Systems · Proc. VLDB Endow. 2024
Data integration and cleaning
data preprocessing
0.812024
CtxPipe: Context-aware Data Preparation Pipeline Construction for Machine Learning · Proc. ACM Manag. Data 2024
Data mining
feature engineering
0.812024
CtxPipe: Context-aware Data Preparation Pipeline Construction for Machine Learning · Proc. ACM Manag. Data 2024
Data mining › anomaly detection
fraud detection
0.812024
VecAug: Unveiling Camouflaged Frauds with Cohort Augmentation for Enhanced Detection · KDD 2024
Machine learning and data management
in-database machine learning
0.812024
Powering In-Database Dynamic Model Slicing for Structured Data Analytics · Proc. VLDB Endow. 2024
Data mining
model selection
0.812024
Database Native Model Selection: Harnessing Deep Neural Networks in Database Systems · Proc. VLDB Endow. 2024
Data mining
representation learning
0.812024
VecAug: Unveiling Camouflaged Frauds with Cohort Augmentation for Enhanced Detection · KDD 2024
Database system architecture and tuning
self-managing database systems
0.812024
NeurDB: an AI-powered autonomous data system · Sci. China Inf. Sci. 2024
Data stream processing › evolving data
concept drift
0.712023
METER: A Dynamic Concept Adaptation Framework for Online Anomaly Detection · Proc. VLDB Endow. 2023
Network security › intrusion detection and prevention › intrusion detection
anomaly detection
0.712023
Robust and Transferable Log-based Anomaly Detection · Proc. ACM Manag. Data 2023

Methods — techniques the papers use, named apart from their topics

hypernetwork · 2.7variational inference · 2.0dynamic thresholding · 2.0attention mechanism · 1.8perturbation-based detection · 1.7fine-tuning · 1.7cohort contextualization · 1.7biscale cohort learning · 1.7stochastic gradient descent · 1.3deep neural network · 1.3neural architecture search · 1.0lightweight machine learning for index tuning · 0.9in-context adaptation · 0.9graph-based index · 0.9early termination · 0.9dynamic context memory · 0.9bayesian meta-training · 0.9environment invariant representation learning · 0.7
YearPublicationVenuePosition
2026 Catching Every Ripple: Enhanced Anomaly Awareness via Dynamic Concept Adaptation
abstract
Online anomaly detection (OAD) plays a pivotal role in real-time analytics and decision-making for evolving data streams. However, existing methods often rely on costly retraining and rigid decision boundaries, limiting their ability to adapt both effectively and efficiently to concept drift in dynamic environments. To address these challenges, we propose DyMETER, a dynamic concept adaptation framework for OAD that unifies on-the-fly parameter shifting and dynamic thresholding within a single online paradigm. DyMETER first learns a static detector on historical data to capture recurring central concepts, and then transitions to a dynamic mode to adapt to new concepts as drift occurs. Specifically, DyMETER employs a novel dynamic concept adaptation mechanism that leverages a hypernetwork to generate instance-aware parameter shifts for the static detector, thereby enabling efficient and effective adaptation without retraining or fine-tuning. To achieve robust and interpretable adaptation, DyMETER introduces a lightweight evolution controller to estimate instance-level concept uncertainty for adaptive updates. Further, DyMETER employs a dynamic threshold optimization module to adaptively recalibrate the decision boundary by maintaining a candidate window of uncertain samples, which ensures continuous alignment with evolving concepts. Extensive experiments demonstrate that DyMETER significantly outperforms existing OAD approaches across a wide spectrum of application scenarios.
Jiaqi Zhu 0002, Shaofeng Cai, Jie Chen 0003, Fang Deng, Beng Chin Ooi, Wenqiao Zhang
IEEE Trans. Pattern Anal. Mach. Intell.2
2026 NeurIDA: Dynamic Modeling for Effective In-Database Analytics
Lingze Zeng, Shaofeng Cai, Naili Xing, Jiaqi Zhu 0002, Gang Chen 0001, Peng Lu 0013, Jian Pei 0001, Beng Chin Ooi
Proc. VLDB Endow.2
2025 NeurDB: On the Design and Implementation of an AI-powered Autonomous Database
Zhanhao Zhao, Shaofeng Cai, Hexiang Pan, Siqi Xiang, Naili Xing, Gang Chen 0001, Beng Chin Ooi, Yanyan Shen, Yuncheng Wu, Meihui Zhang 0001
CIDR2
2025 Investigating Pattern Neurons in Urban Time Series Forecasting
abstract
Urban time series forecasting is crucial for smart city development and is key to sustainable urban management. Although urban time series models (UTSMs) are effective in general forecasting, they often overlook low-frequency events, such as holidays and extreme weather, leading to degraded performance in practical applications. In this paper, we first investigate how UTSMs handle these infrequent patterns from a neural perspective. Based on our findings, we propose $\textbf{P}$attern $\textbf{N}$euron guided $\textbf{Train}$ing ($\texttt{PN-Train}$), a novel training method that features (i) a $\textit{perturbation-based detector}$ to identify neurons responsible for low-frequency patterns in UTSMs, and (ii) a $\textit{fine-tuning mechanism}$ that enhances these neurons without compromising representation learning on high-frequency patterns. Empirical results demonstrate that $\texttt{PN-Train}$ considerably improves forecasting accuracy for low-frequency events while maintaining high performance for high-frequency events. The code is available at https://github.com/cwang-nus/PN-Train.
Chengxin Wang, Shaofeng Cai, Gary Tan
ICLR3
2025 In-Context Adaptation to Concept Drift for Learned Database Operations
abstract
Machine learning has demonstrated transformative potential for database operations, such as query optimization and in-database data analytics. However, dynamic database environments, characterized by frequent updates and evolving data distributions, introduce concept drift, which leads to performance degradation for learned models and limits their practical applicability. Addressing this challenge requires efficient frameworks capable of adapting to shifting concepts while minimizing the overhead of retraining or fine-tuning. In this paper, we propose FLAIR, an online adaptation framework that introduces a new paradigm called \textit{in-context adaptation} for learned database operations. FLAIR leverages the inherent property of data systems, i.e., immediate availability of execution results for predictions, to enable dynamic context construction. By formalizing adaptation as $f:(\mathbf{x} | \mathcal{C}_t) \to \mathbf{y}$, with $\mathcal{C}_t$ representing a dynamic context memory, FLAIR delivers predictions aligned with the current concept, eliminating the need for runtime parameter optimization. To achieve this, FLAIR integrates two key modules: a Task Featurization Module for encoding task-specific features into standardized representations, and a Dynamic Decision Engine, pre-trained via Bayesian meta-training, to adapt seamlessly using contextual information at runtime. Extensive experiments across key database tasks demonstrate that FLAIR outperforms state-of-the-art baselines, achieving up to $5.2\times$ faster adaptation and reducing error by 22.5\% for cardinality estimation.
Jiaqi Zhu 0002, Shaofeng Cai, Yanyan Shen, Gang Chen 0001, Fang Deng, Beng Chin Ooi
ICML2
2025 NeuralCohort: Cohort-aware Neural Representation Learning for Healthcare Analytics
abstract
Electronic health records (EHR) aggregate extensive data critical for advancing patient care and refining intervention strategies. EHR data is essential for epidemiological study, more commonly referred to as cohort study, where patients with shared characteristics or similar diseases are analyzed over time. Unfortunately, existing studies on cohort modeling are limited, struggling to derive fine-grained cohorts or effectively utilize cohort information, which hinders their ability to uncover intrinsic relationships between cohorts. To this end, we propose NeuralCohort, a cohort-aware neural representation learning method that precisely segments patients into finer-grained cohorts via an innovative cohort contextualization mechanism and captures both intra- and inter-cohort information using a Biscale Cohort Learning Module. Designed as a plug-in, NeuralCohort integrates seamlessly with existing backbone models, enhancing their cohort analysis capabilities by infusing deep cohort insights into the representation learning processes. The effectiveness and generalizability of NeuralCohort are validated across extensive real-world EHR datasets. Experimental results demonstrate that NeuralCohort consistently improves the performance of various backbone models, achieving up to an 8.1% increase in AUROC.
Changshuo Liu, Lingze Zeng, Kaiping Zheng, Shaofeng Cai, Beng Chin Ooi, James Wei Luen Yip
ICML4
2025 HAKES: Scalable Vector Database for Embedding Search Service
abstract
Modern deep learning models capture the semantics of complex data by transforming them into high-dimensional embedding vectors. Emerging applications, such as retrieval-augmented generation, use approximate nearest neighbor (ANN) search in the embedding vector space to find similar data. Existing vector databases provide indexes for efficient ANN searches, with graph-based indexes being the most popular due to their low latency and high recall in real-world high-dimensional datasets. However, these indexes are costly to build, suffer from significant contention under concurrent read-write workloads, and scale poorly to multiple servers. Our goal is to build a vector database that achieves high throughput and high recall under concurrent read-write workloads. To this end, we first propose an ANN index with an explicit two-stage design combining a fast filter stage with highly compressed vectors and a refine stage to ensure recall, and we devise a novel lightweight machine learning technique to fine-tune the index parameters. We introduce an early termination check to dynamically adapt the search process for each query. Next, we add support for writes while maintaining search performance by decoupling the management of the learned parameters. Finally, we design HAKES, a distributed vector database that serves the new index in a disaggregated architecture. We evaluate our index and system against 12 state-of-the-art indexes and three distributed vector databases, using high-dimensional embedding datasets generated by deep learning models. The experimental results show that our index outperforms index baselines in the high recall region and under concurrent read-write workloads. Furthermore, HAKES is scalable and achieves up to 16x higher throughputs than the baselines.
Guoyu Hu, Shaofeng Cai, Tien Tuan Anh Dinh, Zhongle Xie, Cong Yue, Gang Chen 0001, Beng Chin Ooi
Proc. VLDB Endow.2
2024 VecAug: Unveiling Camouflaged Frauds with Cohort Augmentation for Enhanced Detection
abstract
Fraud detection presents a challenging task characterized by ever-evolving fraud patterns and scarce labeled data. Existing methods predominantly rely on graph-based or sequence-based approaches. While graph-based approaches connect users through shared entities to capture structural information, they remain vulnerable to fraudsters who can disrupt or manipulate these connections. In contrast, sequence-based approaches analyze users' behavioral patterns, offering robustness against tampering but overlooking the interactions between similar users. Inspired by cohort analysis in retention and healthcare, this paper introduces VecAug, a novel cohort-augmented learning framework that addresses these challenges by enhancing the representation learning of target users with personalized cohort information. To this end, we first propose a vector burn-in technique for automatic cohort identification, which retrieves a task-specific cohort for each target user. Then, to fully exploit the cohort information, we introduce an attentive cohort aggregation technique for augmenting target user representations. To improve the robustness of such cohort augmentation, we also propose a novel label-aware cohort neighbor separation mechanism to distance negative cohort neighbors and calibrate the aggregated cohort information. By integrating this cohort information with target user representations, VecAug enhances the modeling capacity and generalization capabilities of the model to be augmented. Our framework is flexible and can be seamlessly integrated with existing fraud detection models. We deploy our framework on e-commerce platforms and evaluate it on three fraud detection datasets, and results show that VecAug improves the detection performance of base models by up to 2.48% in AUC and 22.5% in [email protected], outperforming state-of-the-art methods significantly.
Fei Xiao 0015, Shaofeng Cai, Gang Chen 0001, H. V. Jagadish, Beng Chin Ooi, Meihui Zhang 0001
KDD2
2024 Do LLMs Understand Visual Anomalies? Uncovering LLM's Capabilities in Zero-shot Anomaly Detection
abstract
Large vision-language models (LVLMs) are markedly proficient in deriving visual representations guided by natural language. Recent explorations have utilized LVLMs to tackle zero-shot visual anomaly detection (VAD) challenges by pairing images with textual descriptions indicative of normal and abnormal conditions, referred to as anomaly prompts. However, existing approaches depend on static anomaly prompts that are prone to cross-semantic ambiguity, and prioritize global image-level representations over crucial local pixel-level image-to-text alignment that is necessary for accurate anomaly localization. In this paper, we present ALFA, a training-free approach designed to address these challenges via a unified model. We propose a run-time prompt adaptation strategy, which first generates informative anomaly prompts to leverage the capabilities of a large language model (LLM). This strategy is enhanced by a contextual scoring mechanism for per-image anomaly prompt adaptation and cross-semantic ambiguity mitigation. We further introduce a novel fine-grained aligner to fuse local pixel-level semantics for precise anomaly localization, by projecting the image-text alignment from global to local semantic spaces. Extensive evaluations on the challenging MVTec and VisA datasets confirm ALFA's effectiveness in harnessing the language potential for zero-shot VAD, achieving significant PRO improvements of 12.1% on MVTec AD and 8.9% on VisA compared to state-of-the-art zero-shot VAD approaches.
Jiaqi Zhu 0002, Shaofeng Cai, Fang Deng, Beng Chin Ooi, Junran Wu
ACM Multimedia2
2024 NeurDB: an AI-powered autonomous data system
Beng Chin Ooi, Shaofeng Cai, Gang Chen 0001, Yanyan Shen, Kian-Lee Tan, Yuncheng Wu, Xiaokui Xiao, Naili Xing, Cong Yue, Lingze Zeng, Meihui Zhang 0001, Zhanhao Zhao
Sci. China Inf. Sci.2
2024 CtxPipe: Context-aware Data Preparation Pipeline Construction for Machine Learning
abstract
Machine learning models are only as good as their training data. Simple models trained on well-chosen features extracted from the raw data often outperform complex models trained directly on the raw data. Data preparation pipelines, which clean and derive features from the data, are therefore important for machine learning applications. However, constructing such pipelines is a resource-intensive process that involves deep human expertise. Our goal is to design an efficient framework for automatically finding high-quality data preparation pipelines. The main challenge is how to explore a large search space of pipeline components with the objective of computing features that maximize the performance of the downstream models. Existing solutions are limited in terms of feature quality, which results in low accuracies of the downstream models, while incurring significant runtime overhead. We present CtxPipe, a novel framework that addresses the limitations of previous works by leveraging contextual information to improve the pipeline construction process. Specifically, it uses pre-trained embedding models to capture the data semantics, which are then used to guide the selection of pipeline components. We implement CtxPipe with deep reinforcement learning and evaluate it against state-of-the-art automated pipeline construction solutions. Our comprehensive experiments demonstrate that CtxPipe outperforms all of the baselines in both model performance and runtime cost.
Shaofeng Cai, Tien Tuan Anh Dinh, Zhiyong Huang 0010, Beng Chin Ooi
Proc. ACM Manag. Data2
2024 Database Native Model Selection: Harnessing Deep Neural Networks in Database Systems
abstract
The growing demand for advanced analytics beyond statistical aggregation calls for database systems that support effective model selection of deep neural networks (DNNs). However, existing model selection strategies are based on either training-based algorithms that deliver high-performing models at the expense of high computational cost, or training-free algorithms that enhance computational efficiency with reduced effectiveness. These strategies often disregard computational cost and response time Service-Level Objectives (SLOs), which are of concern to average or budget-conscious machine learning users. In addition, they lack a well-designed integration of the model selection algorithms with DBMSs, which hinders efficient in-database model selection. This paper presents TRAILS, a resource-efficient and SLO-aware in-database model selection system. To leverage the strengths of both training-free and training-based model selection, we first characterize nine state-of-the-art training-free model evaluation metrics and propose a more effective one named JacFlow, and then, restructure the conventional model selection procedure into two phases: filtering and refinement. A novel coordinator is also introduced to strike a balance between the high efficiency of train-free algorithms and the high effectiveness of training-based algorithms, ensuring high-performing model selection while adhering to target SLOs. Moreover, we incorporate the proposed algorithm into PostgreSQL to develop TRAILS, thereby both enhancing resource efficiency and reducing model selection latency. This integration establishes a foundation for declarative model definition and selection within DBMSs. Empirical results demonstrate that our TRAILS reduces model selection time and computational expenses considerably by up to 24.38x and 29.32x respectively compared to existing model selection systems.
Naili Xing, Shaofeng Cai, Gang Chen 0001, Zhaojing Luo, Beng Chin Ooi, Jian Pei 0001
Proc. VLDB Endow.2
2024 Powering In-Database Dynamic Model Slicing for Structured Data Analytics
abstract
Relational database management systems (RDBMS) are widely used for the storage of structured data. To derive insights beyond statistical aggregation, we typically have to extract specific subdatasets from the database using conventional database operations, and then apply deep neural networks (DNN) training and inference on these subdatasets in a separate analytics system. The process can be prohibitively expensive, especially when there are various subdatasets extracted for different analytical purposes. This calls for efficient in-database support of advanced analytical methods. In this paper, we introduce LEADS, a novel SQL-aware dynamic model slicing technique to customize models for specified SQL queries. LEADS improves the predictive modeling of structured data via the mixture of experts (MoE) and maintains efficiency by a SQL-aware gating network. At the core of LEADS is the construction of a general model with multiple expert sub-models trained over the database. The MoE scales up the modeling capacity, enhances effectiveness, and preserves efficiency by activating necessary experts via the SQL-aware gating network during inference. To support in-database analytics, we build an inference extension that integrates LEADS onto PostgreSQL. Our extensive experiments on real-world datasets demonstrate that LEADS consistently outperforms the baseline models, and the in-database inference extension delivers a considerable reduction in inference latency compared to traditional solutions.
Lingze Zeng, Naili Xing, Shaofeng Cai, Gang Chen 0001, Beng Chin Ooi, Jian Pei 0001, Yuncheng Wu
Proc. VLDB Endow.3
2023 Robust and Transferable Log-based Anomaly Detection
abstract
Log messages provide a valuable source of runtime information for ensuring the safety and consistency of systems. Recently, many machine learning and deep learning methods have been proposed to automatically detect anomalous log messages, obviating the need for manual detection by experts. However, we find that in practice, the effectiveness of existing learning-based methods is severely affected by incomplete information and distribution shift. Specifically, each log message can actually be parsed into a fixed number of key information fields, while existing methods analyze log messages using only the log event information and ignore other useful information fields that can be critical to anomaly detection. Further, the distribution of real-world log messages changes continuously due to the dynamic nature of the runtime environment and thus, a detection model conventionally trained based on the unrealistic i.i.d. assumption may not provide the expected and consistent performance. In this paper, we present a robust and transferable anomaly detection framework RT-Log to address the above problems. To perform a comprehensive analysis of log messages, we introduce an adaptive relation modeling technique, which captures feature interactions among log information fields selectively and dynamically for effective and interpretable log representations. To establish its robustness and transferability, we propose a general environment generalization technique for learning the environment invariant representations that can generalize across different runtime environments. We evaluate the anomaly detection performance of RT-Log on large real-world datasets. Extensive experimental results demonstrate that RT-Log consistently outperforms state-of-the-art methods by a significant margin under different settings.
Peng Jia 0004, Shaofeng Cai, Beng Chin Ooi, Pinghui Wang, Yiyuan Xiong
Proc. ACM Manag. Data2
2023 Regularized Pairwise Relationship based Analytics for Structured Data
abstract
In line with the increasing machine learning model inference accuracy, deep learning (DL) models have been increasingly applied to structured data for a wide spectrum of real-world applications, including product recommendations, online advertisement, healthcare analytics and risk analysis. However, unlike unstructured data, structured data is high-dimensional and sparse and therefore engenders a large number of parameters in DL, making DL models more prone to overfitting. To alleviate the overfitting problem, various regularization methods have been designed to constrain the model parameters as a means to control the model complexity. Unfortunately, these methods are often restricted to regularizing the parameter values directly without considering the intrinsic correlations and dependencies between attribute fields of structured data which is however key to effective structured data modeling. In this paper, we re-examine DL for structured data from a new perspective of attribute interactions. In particular, we seek to explicitly model and regularize the pairwise relationships between attribute fields of structured data, in a field-adaptive manner, via a proposed attentive and interpretable framework called ATT-Reg. Specifically, in this framework, a set of attentive weight matrices are introduced to each attribute field for modeling obviously different relationships with its neighboring attribute fields. Further, we derive from the Bayesian viewpoint a novel Attentive Regularization method for imposing adaptive regularization strengths on different pairs of attribute fields, based on the informativeness of their relationship, which is calculated using both data-driven information and functional dependency (FD) knowledge. Such adaptive regularization facilitates each attribute field to learn discriminative and diversified representations for more effective predictive analytics. We also develop a feature attribution method for supporting more interpretable predictions We validate the effectiveness of our ATT-Reg on six real-world datasets. Extensive experimental results show that ATT-Reg achieves significant improvement over state-of-the-art graph models, attentive models as well as regularization methods and supports an excellent degree of interpretation.
Zhaojing Luo, Shaofeng Cai, Yatong Wang, Beng Chin Ooi
Proc. ACM Manag. Data2
2023 METER: A Dynamic Concept Adaptation Framework for Online Anomaly Detection
abstract
Real-time analytics and decision-making require online anomaly detection (OAD) to handle drifts in data streams efficiently and effectively. Unfortunately, existing approaches are often constrained by their limited detection capacity and slow adaptation to evolving data streams, inhibiting their efficacy and efficiency in handling concept drift , which is a major challenge in evolving data streams. In this paper, we introduce METER, a novel dynamic concept adaptation framework that introduces a new paradigm for OAD. METER addresses concept drift by first training a base detection model on historical data to capture recurring central concepts , and then learning to dynamically adapt to new concepts in data streams upon detecting concept drift. Particularly, METER employs a novel dynamic concept adaptation technique that leverages a hypernetwork to dynamically generate the parameter shift of the base detection model, providing a more effective and efficient solution than conventional retraining or fine-tuning approaches. Further, METER incorporates a lightweight drift detection controller, underpinned by evidential deep learning, to support robust and interpretable concept drift detection. We conduct an extensive experimental evaluation, and the results show that METER significantly outperforms existing OAD approaches in various application scenarios.
Jiaqi Zhu 0002, Shaofeng Cai, Fang Deng, Beng Chin Ooi, Wenqiao Zhang
Proc. VLDB Endow.2
2022 NASI: Label- and Data-agnostic Neural Architecture Search at Initialization
Yao Shu, Shaofeng Cai, Zhongxiang Dai, Beng Chin Ooi, Kian Hsiang Low
ICLR2
2022 DyHealth: Making Neural Networks Dynamic for Effective Healthcare Analytics
abstract
In National University Hospital (NUH) in Singapore, we conduct healthcare analytics that analyzes heterogeneous electronic medical records (EMR) to support effective clinical decision-making on a daily basis. Existing work mainly focuses on multimodality for extracting complementary information from different modalities, and/or interpretability for providing interpretable prediction results. However, real-world healthcare analytics has presented another major challenge, i.e., the available modalities evolve or change intermittently. Addressing this challenge requires deployed models to be adaptive to such dynamic modality changes. To meet the aforementioned requirement, we develop a modular, multimodal and interpretable framework DyHealth to enable dynamic healthcare analytics in clinical practice. Specifically, different modalities are processed within their respective data modules that adhere to the interface defined by DyHealth. The extracted information from different modalities is integrated subsequently in our proposed Multimodal Fusion Module in DyHealth. In order to better handle modality changes at runtime, we further propose exponential increasing/decreasing mechanisms to support modality "hot-plug". We also devise a novel modality-based attention mechanism for providing fine-grained interpretation results on a per-input basis. We conduct a pilot evaluation of DyHealth on the patients' EMR data from NUH, in which DyHealth achieves superior performance and therefore, is promising to roll out for hospital-wide deployment. We also validate DyHealth in two public EMR datasets. Experimental results confirm the effectiveness, flexibility, and extensibility of DyHealth in supporting multimodal and interpretable healthcare analytics.
Kaiping Zheng, Shaofeng Cai, Horng Ruey Chua, Melanie Herschel, Meihui Zhang 0001, Beng Chin Ooi
Proc. VLDB Endow.2
2021 Adaptive Knowledge Driven Regularization for Deep Neural Networks
abstract
In many real-world applications, the amount of data available for training is often limited, and thus inductive bias and auxiliary knowledge are much needed for regularizing model training. One popular regularization method is to impose prior distribution assumptions on model parameters, and many recent works also attempt to regularize training by integrating external knowledge into specific neurons. However, existing regularization methods did not take account of the interaction between connected neuron pairs, which is invaluable internal knowledge for adaptive regularization for better representation learning as training progresses. In this paper, we explicitly take into account the interaction between connected neurons, and propose an adaptive internal knowledge driven regularization method, CORR-Reg. The key idea of CORR-Reg is to give a higher significance weight to connections of more correlated neuron pairs. The significance weights adaptively identify more important input neurons for each neuron. Instead of regularizing connection model parameters with a static strength such as weight decay, CORR-Reg imposes weaker regularization strength on more significant connections. As a consequence, neurons attend to more informative input features and thus learn more diversified and discriminative representation. We derive CORR-Reg with Bayesian inference framework and propose a novel optimization algorithm with Lagrange multiplier method and Stochastic Gradient Descent. Extensive evaluations on diverse benchmark datasets and neural network structures show that CORR-Reg achieves significant improvement over state-of-the-art regularization methods.
Zhaojing Luo, Shaofeng Cai, Can Cui 0019, Beng Chin Ooi, Yang Yang 0002
AAAI2
2021 ARM-Net: Adaptive Relation Modeling Network for Structured Data
abstract
Relational databases are the de facto standard for storing and querying structured data, and extracting insights from structured data requires advanced analytics. Deep neural networks (DNNs) have achieved super-human prediction performance in particular data types, e.g., images. However, existing DNNs may not produce meaningful results when applied to structured data. The reason is that there are correlations and dependencies across combinations of attribute values in a table, and these do not follow simple additive patterns that can be easily mimicked by a DNN. The number of possible such cross features is combinatorial, making them computationally prohibitive to model. Furthermore, the deployment of learning models in real-world applications has also highlighted the need for interpretability, especially for high-stakes applications, which remains another issue of concern to DNNs. In this paper, we present ARM-Net, an adaptive relation modeling network tailored for structured data, and a lightweight framework ARMOR based on ARM-Net for relational data analytics. The key idea is to model feature interactions with cross features selectively and dynamically, by first transforming the input features into exponential space, and then determining the interaction order and interaction weights adaptively for each cross feature. We propose a novel sparse attention mechanism to dynamically generate the interaction weights given the input tuple, so that we can explicitly model cross features of arbitrary orders with noisy features filtered selectively. Then during model inference, ARM-Net can specify the cross features being used for each prediction for higher accuracy and better interpretability. Our extensive experiments on real-world datasets demonstrate that ARM-Net consistently outperforms existing models and provides more interpretable predictions for data-driven decision making.
Shaofeng Cai, Kaiping Zheng, Gang Chen 0001, H. V. Jagadish, Beng Chin Ooi, Meihui Zhang 0001
SIGMOD Conference1
2021 Dynamic Routing Networks
abstract
The deployment of deep neural networks in real-world applications is mostly restricted by their high inference costs. Extensive efforts have been made to improve the accuracy with expert-designed or algorithm-searched architectures. However, the incremental improvement is typically achieved with increasingly more expensive models that only a small portion of input instances really need. Inference with a static architecture that processes all input instances via the same transformation would thus incur unnecessary computational costs. Therefore, customizing the model capacity in an instance-aware manner is much needed for higher inference efficiency. In this paper, we propose Dynamic Routing Networks (DRNets), which support efficient instance-aware inference by routing the input instance to only necessary transformation branches selected from a candidate set of branches for each connection between transformation nodes. The branch selection is dynamically determined via the corresponding branch importance weights, which are first generated from lightweight hyper-networks (RouterNets) and then recalibrated with Gumbel-Softmax before the selection. Extensive experiments show that DRNets can reduce a substantial amount of parameter size and FLOPs during inference with prediction performance comparable to state-of-the-art architectures.
Shaofeng Cai, Yao Shu, Wei Wang 0059
WACV1
2021 GraphTCN: Spatio-Temporal Interaction Modeling for Human Trajectory Prediction
abstract
Predicting the future paths of an agent's neighbors accurately and in a timely manner is central to the autonomous applications for collision avoidance. Conventional approaches, e.g., LSTM-based models, take considerable computational costs in the prediction, especially for the long sequence prediction. To support more efficient and accurate trajectory predictions, we propose a novel CNN-based spatial-temporal graph framework GraphTCN, which models the spatial interactions as social graphs and captures the spatio-temporal interactions with a modified temporal convolutional network. In contrast to conventional models, both the spatial and temporal modeling of our model are computed within each local time window. Therefore, it can be executed in parallel for much higher efficiency, and meanwhile with accuracy comparable to best-performing approaches. Experimental results confirm that our model achieves better performance in terms of both efficiency and accuracy as compared with state-of-the-art models on various trajectory prediction benchmark datasets.
Chengxin Wang, Shaofeng Cai, Gary Tan
WACV2
2021 Improving Data Analytics with Fast and Adaptive Regularization
abstract
Deep Learning and Machine Learning models have recently been shown to be effective in many real world applications. While these models achieve increasingly better predictive performance, their structures have also become much more complex. A common and difficult problem for complex models is overfitting. Regularization is used to penalize the complexity of the model in order to avoid overfitting. However, in most learning frameworks, regularization function is usually set with some hyper-parameters where the best setting is difficult to find. In this paper, we propose an adaptive regularization method, as part of a large end-to-end healthcare data analytics software stack, which effectively addresses the above difficulty. First, we propose a general adaptive regularization method based on Gaussian Mixture (GM) to learn the best regularization function according to the observed parameters. Second, we develop an effective update algorithm which integrates Expectation Maximization (EM) with Stochastic Gradient Descent (SGD). Third, we design a lazy update and sparse update algorithm to reduce the computational cost by 4x and 20x, respectively. The overall regularization framework is fast, adaptive, and easy-to-use. We validate the effectiveness of our regularization method through an extensive experimental study over 14 standard benchmark datasets and three kinds of deep learning/machine learning models. The results illustrate that our proposed adaptive regularization method achieves significant improvement over state-of-the-art regularization methods.
Zhaojing Luo, Shaofeng Cai, Gang Chen 0001, Jinyang Gao, Wang-Chien Lee, Kee Yuan Ngiam, Meihui Zhang 0001
IEEE Trans. Knowl. Data Eng.2
2020 Understanding Architectures Learnt by Cell-based Neural Architecture Search
Yao Shu, Wei Wang 0059, Shaofeng Cai
ICLR3
2020 TRACER: A Framework for Facilitating Accurate and Interpretable Analytics for High Stakes Applications
abstract
In high stakes applications such as healthcare and finance analytics, the interpretability of predictive models is required and necessary for domain practitioners to trust the predictions. Traditional machine learning models, e.g., logistic regression (LR), are easy to interpret in nature. However, many of these models aggregate time-series data without considering the temporal correlations and variations. Therefore, their performance cannot match up to recurrent neural network (RNN) based models, which are nonetheless difficult to interpret. In this paper, we propose a general framework TRACER to facilitate accurate and interpretable predictions, with a novel model TITV devised for healthcare analytics and other high stakes applications such as financial investment and risk management. Different from LR and other existing RNN-based models, TITV is designed to capture both the time-invariant and the time-variant feature importance using a feature-wise transformation subnetwork and a self-attention subnetwork, for the feature influence shared over the entire time series and the time-related importance respectively. Healthcare analytics is adopted as a driving use case, and we note that the proposed TRACER is also applicable to other domains, e.g., fintech. We evaluate the accuracy of TRACER extensively in two real-world hospital datasets, and our doctors/clinicians further validate the interpretability of TRACER in both the patient level and the feature level. Besides, TRACER is also validated in a critical financial application. The experimental results confirm that TRACER facilitates both accurate and interpretable analytics for high stakes applications.
Kaiping Zheng, Shaofeng Cai, Horng Ruey Chua, Wei Wang 0059, Kee Yuan Ngiam, Beng Chin Ooi
SIGMOD Conference2
2020 Privacy Preserving Vertical Federated Learning for Tree-based Models
Yuncheng Wu, Shaofeng Cai, Xiaokui Xiao, Gang Chen 0001, Beng Chin Ooi
Proc. VLDB Endow.2
2020 The Disruptions of 5G on Data-Driven Technologies and Applications
abstract
With 5G on the verge of being adopted as the next mobile network, there is a need to analyze its impact on the landscape of computing and data management. In this paper, we analyze the impact of 5G on both traditional and emerging technologies and project our view on future research challenges and opportunities. With a predicted increase of 10-100× in bandwidth and 5-10x decrease in latency, 5G is expected to be the main enabler for smart cities, smart IoT and efficient healthcare, where machine learning is conducted at the edge. In this context, we investigate how 5G can help the development of federated learning. Network slicing, another key feature of 5G, allows running multiple isolated networks on the same physical infrastructure. However, security remains the main concern in the context of virtualization, multi-tenancy and high device density. Formal verification of 5G networks can be applied to detect security issues in massive virtualized environments. In summary, 5G will make the world even more densely and closely connected. What we have experienced in 4G connectivity will pale in comparison to the vast amounts of possibilities engendered by 5G.
Dumitrel Loghin, Shaofeng Cai, Gang Chen 0001, Tien Tuan Anh Dinh, Feiyi Fan, Qian Lin 0002, Janice Ng, Beng Chin Ooi, Xutao Sun, Quang-Trung Ta, Wei Wang 0059, Xiaokui Xiao, Yang Yang 0002, Meihui Zhang 0001
IEEE Trans. Knowl. Data Eng.2
2019 Model Slicing for Supporting Complex Analytics with Elastic Inference Cost and Resource Constraints
abstract
Deep learning models have been used to support analytics beyond simple aggregation, where deeper and wider models have been shown to yield great results. These models consume a huge amount of memory and computational operations. However, most of the large-scale industrial applications are often computational budget constrained. In practice, the peak workload of inference service could be 10x higher than the average cases, with the presence of unpredictable extreme cases. Lots of computational resources could be wasted during off-peak hours and the system may crash when the workload exceeds system capacity. How to support deep learning services with dynamic workload cost-efficiently remains a challenging problem. In this paper, we address the challenge with a general and novel training scheme called model slicing , which enables deep learning models to provide predictions within the prescribed computational resource budget dynamically. Model slicing could be viewed as an elastic computation solution without requiring more computational resources. Succinctly, each layer in the model is divided into groups of contiguous block of basic components (i.e. neurons in dense layers and channels in convolutional layers), and then partially ordered relation is introduced to these groups by enforcing that groups participated in each forward pass always starts from the first group to the dynamically-determined rightmost group. Trained by dynamically indexing the rightmost group with a single parameter slice rate , the network is engendered to build up group-wise and residual representation. Then during inference, a sub-model with fewer groups can be readily deployed for efficiency whose computation is roughly quadratic to the width controlled by the slice rate. Extensive experiments show that models trained with model slicing can effectively support on-demand workload with elastic inference cost.
Shaofeng Cai, Gang Chen 0001, Beng Chin Ooi, Jinyang Gao
Proc. VLDB Endow.1
2018 Adaptive Lightweight Regularization Tool for Complex Analytics
abstract
Deep Learning and Machine Learning models have recently been shown to be effective in many real world applications. While these models achieve increasingly better predictive performance, their structures have also become much more complex. A common and difficult problem for complex models is overfitting. Regularization is used to penalize the complexity of the model in order to avoid overfitting. However, in most learning frameworks, regularization function is usually set as some hyper parameters, and therefore the best setting is difficult to find. In this paper, we propose an adaptive regularization method, as part of a large end-to-end healthcare data analytics software stack, which effectively addresses the above difficulty. First, we propose a general adaptive regularization method based on Gaussian Mixture (GM) to learn the best regularization function according to the observed parameters. Second, we develop an effective update algorithm which integrates Expectation Maximization (EM) with Stochastic Gradient Descent (SGD). Third, we design a lazy update algorithm to reduce the computational cost by 4x. The overall regularization framework is fast, adaptive and easy-to-use. We validate the effectiveness of our regularization method through an extensive experimental study over 13 standard benchmark datasets and three kinds of deep learning/machine learning models. The results illustrate that our proposed adaptive regularization method achieves significant improvement over state-of-the-art regularization methods.
Zhaojing Luo, Shaofeng Cai, Jinyang Gao, Meihui Zhang 0001, Kee Yuan Ngiam, Gang Chen 0001, Wang-Chien Lee
ICDE2