Publications

Data discovery from data lakes is an essential application in modern data science. While many previous studies focused on improving the efficiency and effectiveness of data discovery, little attention has been paid to the usability of such applications. In particular, exploring data discovery results can be cumbersome due to the cognitive load involved in understanding raw tabular results and identifying insights to draw conclusions. To address this challenge, we introduce a new problem — visualization recommendation for data discovery over data lakes — which aims at automatically identifying visualizations that highlight relevant or desired trends in the results returned by data discovery engines. We propose LakeVisage, an end-to-end framework as the first solution to this problem. Given a data lake, a data discovery engine, and a user-specified query table, LakeVisage intelligently explores the space of visualizations and recommends the most useful and “interesting” visualization plans. To this end, we developed (i) approaches to smartly construct the candidate visualization plans from the results of the data discovery engine and (ii) effective pruning strategies to filter out less interesting plans so as to accelerate the visual analysis. Experimental results on real data lakes show that our proposed techniques can lead to an order of magnitude speedup in visualization recommendation. We also conduct a comprehensive user study to demonstrate that LakeVisage offers convenience to users in real data analysis applications by enabling them seamlessly get started with the tasks and performing explorations flexibly.

NL2SQL approaches have greatly benefited from the impressive capabilities of large language models (LLMs). In particular, bootstrapping an NL2SQL system for a specific domain can be as simple as instructing an LLM with sufficient contextual information, such as schema details and translation demonstrations. However, building an accurate system still requires the rigorous task of selecting the right context for each query-including identifying relevant schema elements, cell values, and suitable exemplars that help the LLM understand domain-specific nuances. Retrieval-based methods have become the go-to approach for identifying such context. While effective, these methods introduce additional inference-time costs due to the retrieval process. In this paper, we argue that production scenarios demand high-precision, high-performance NL2SQL systems, rather than simply high-quality SQL generation, which is the focus of most current NL2SQL approaches. In such scenarios, the careful selection of a static set of exemplars-capturing the intricacies of the query log, target database, SQL constructs, and execution latencies-plays a more crucial role than exemplar selection based solely on similarity. The key challenge, however, lies in identifying a representative set of exemplars for a given production setting. To this end, we propose a prompt optimization framework that not only addresses the high-precision requirement but also optimizes the performance of the generated SQL through multi-objective optimization. Preliminary empirical analysis demonstrates the effectiveness of the proposed framework.

Retrieval from graph data is crucial for augmenting large language models (LLM) with both open-domain knowledge and private enterprise data, and it is also a key component in the recent GraphRAG system (edge et al., 2024). Despite decades of research on knowledge graphs and knowledge base question answering, leading LLM frameworks (e.g. Langchain and LlamaIndex) have only minimal support for retrieval from modern encyclopedic knowledge graphs like Wikidata. In this paper, we analyze the root cause and suggest that modern RDF knowledge graphs (e.g. Wikidata, Freebase) are less efficient for LLMs due to overly large schemas that far exceed the typical LLM context window, use of resource identifiers, overlapping relation types and lack of normalization. As a solution, we propose property graph views on top of the underlying RDF graph that can be efficiently queried by LLMs using Cypher. We instantiated this idea on Wikidata and introduced CypherBench, the first benchmark with 11 large-scale, multi-domain property graphs with 7.8 million entities and over 10,000 questions. To achieve this, we tackled several key challenges, including developing an RDF-to-property graph conversion engine, creating a systematic pipeline for text-to-Cypher task generation, and designing new evaluation metrics.

Large language models (LLMs), despite their impressive capabilities in natural language understanding tasks in open-domain, often lack effectiveness with similar tasks in enterprise applications due to potential hallucinations, weak multi-hop reasoning ability, and limitations in adapting to heterogeneous data types, among others. Such issues primarily arise due to the absence of private, on-premises enterprises from an LLM’s training corpus. Knowledge-intensive tasks in enterprise often require multi-step reasoning, deep contextual understanding, and integration of information stored and accessed in heterogeneous formats (e.g., tables, graphs, documents, and JSON), which LLMs aren’t inherently equipped to handle without significant adaptation. To this end, retrieval augmented generation (RAG) offers promise in instrumenting such adaptations on demand. While RAG-based approaches focus on controlling the generation and mitigating hallucinations, existing solutions are not sufficient for the requirements of the enterprise settings. In this paper, we outline our approaches toward understanding and implementing a more effective RAG workflow in the wild. To achieve the goal, we draw on the cognitive science concepts of System 1 (fast, intuitive thinking) and System 2 (slow, deliberate, analytical thinking.) In particular, we discuss how existing RAG approaches are more aligned to System 1 and propose to shift from traditional single-model architectures to compound AI systems within a System 2 framework to improve RAG, especially in complex enterprise applications. Such compound AI systems adopt a more systematic approach by assigning specialized tasks to different intelligent agents, optimizing retrieval and generation performance with a retrieval-augmented generation workflow.

Large language models (LLMs) are proficient at generating fluent text with minimal task-specific supervision. Yet, their ability to provide well-grounded rationalizations for knowledge-intensive tasks remains under-explored. Such tasks, like commonsense multiple-choice questions, require rationales based on world knowledge to support predictions and refute alternate options. We consider the task of generating knowledge-guided rationalization in natural language by using expert-written examples in a few-shot manner. Surprisingly, crowd-workers preferred knowledge-grounded rationales over crowdsourced rationalizations, citing their factuality, sufficiency, and comprehensive refutations. Although LLMs-generated rationales were preferable, further improvements in conciseness and novelty are required. In another study, we show how rationalization of incorrect model predictions erodes humans’ trust in LLM-generated rationales. Motivated by these observations, we create a two-stage pipeline to review task predictions and eliminate potential incorrect decisions before rationalization, enabling trustworthy rationale generation.