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Renggli, Cedric
Fundamental Challenges in Evaluating Text2SQL Solutions and Detecting Their Limitations
Renggli, Cedric, Ilyas, Ihab F., Rekatsinas, Theodoros
In this work, we dive into the fundamental challenges of evaluating Text2SQL solutions and highlight potential failure causes and the potential risks of relying on aggregate metrics in existing benchmarks. We identify two largely unaddressed limitations in current open benchmarks: (1) data quality issues in the evaluation data, mainly attributed to the lack of capturing the probabilistic nature of translating a natural language description into a structured query (e.g., NL ambiguity), and (2) the bias introduced by using different match functions as approximations for SQL equivalence. To put both limitations into context, we propose a unified taxonomy of all Text2SQL limitations that can lead to both prediction and evaluation errors. We then motivate the taxonomy by providing a survey of Text2SQL limitations using state-of-the-art Text2SQL solutions and benchmarks. We describe the causes of limitations with real-world examples and propose potential mitigation solutions for each category in the taxonomy. We conclude by highlighting the open challenges encountered when deploying such mitigation strategies or attempting to automatically apply the taxonomy.
Incremental IVF Index Maintenance for Streaming Vector Search
Mohoney, Jason, Pacaci, Anil, Chowdhury, Shihabur Rahman, Minhas, Umar Farooq, Pound, Jeffery, Renggli, Cedric, Reyhani, Nima, Ilyas, Ihab F., Rekatsinas, Theodoros, Venkataraman, Shivaram
The prevalence of vector similarity search in modern machine IVF indexes out-of-the-box do not have the notion of inserting learning applications and the continuously changing nature of data new vectors or deleting existing vectors once constructed. Indeed, processed by these applications necessitate efficient and effective the most common method used by practitioners today is to rebuild index maintenance techniques for vector search indexes. Designed the index from scratch to reflect any updates that have accumulated primarily for static workloads, existing vector search indexes degrade over time. However, depending on the scale of the vector in search quality and performance as the underlying data is dataset and the volume and frequency of updates, a full index rebuild updated unless costly index reconstruction is performed. To address can be prohibitively expensive. For example, it takes multiple this, we introduce Ada-IVF, an incremental indexing methodology days to rebuild an IVF index from scratch for billion-scale vector for Inverted File (IVF) indexes. Ada-IVF consists of 1) an adaptive datasets [21, 69], making it necessary to revisit how updates can maintenance policy that decides which index partitions are problematic be reflected. Devising such an update mechanism consists of readjusting for performance and should be repartitioned and 2) a local the partitioning of the high-dimensional space defined by re-clustering mechanism that determines how to repartition them.
Co-design Hardware and Algorithm for Vector Search
Jiang, Wenqi, Li, Shigang, Zhu, Yu, Licht, Johannes de Fine, He, Zhenhao, Shi, Runbin, Renggli, Cedric, Zhang, Shuai, Rekatsinas, Theodoros, Hoefler, Torsten, Alonso, Gustavo
Vector search has emerged as the foundation for large-scale information retrieval and machine learning systems, with search engines like Google and Bing processing tens of thousands of queries per second on petabyte-scale document datasets by evaluating vector similarities between encoded query texts and web documents. As performance demands for vector search systems surge, accelerated hardware offers a promising solution in the post-Moore's Law era. We introduce FANNS, an end-to-end and scalable vector search framework on FPGAs. Given a user-provided recall requirement on a dataset and a hardware resource budget, FANNS automatically co-designs hardware and algorithm, subsequently generating the corresponding accelerator. The framework also supports scale-out by incorporating a hardware TCP/IP stack in the accelerator. FANNS Figure 1: FANNS co-designs the hardware and algorithm for attains up to 23.0 and 37.2 speedup compared to FPGA and CPU vector search. The generated FPGA-based accelerators outperform baselines, respectively, and demonstrates superior scalability to GPUs significantly in scale-out experiments.
On Convergence of Nearest Neighbor Classifiers over Feature Transformations
Rimanic, Luka, Renggli, Cedric, Li, Bo, Zhang, Ce
The k-Nearest Neighbors (kNN) classifier is a fundamental non-parametric machine learning algorithm. However, it is well known that it suffers from the curse of dimensionality, which is why in practice one often applies a kNN classifier on top of a (pre-trained) feature transformation. From a theoretical perspective, most, if not all theoretical results aimed at understanding the kNN classifier are derived for the raw feature space. This leads to an emerging gap between our theoretical understanding of kNN and its practical applications. In this paper, we take a first step towards bridging this gap. We provide a novel analysis on the convergence rates of a kNN classifier over transformed features. This analysis requires in-depth understanding of the properties that connect both the transformed space and the raw feature space. More precisely, we build our convergence bound upon two key properties of the transformed space: (1) safety -- how well can one recover the raw posterior from the transformed space, and (2) smoothness -- how complex this recovery function is. Based on our result, we are able to explain why some (pre-trained) feature transformations are better suited for a kNN classifier than other. We empirically validate that both properties have an impact on the kNN convergence on 30 feature transformations with 6 benchmark datasets spanning from the vision to the text domain.
Scalable Transfer Learning with Expert Models
Puigcerver, Joan, Riquelme, Carlos, Mustafa, Basil, Renggli, Cedric, Pinto, Andrรฉ Susano, Gelly, Sylvain, Keysers, Daniel, Houlsby, Neil
Transfer of pre-trained representations can improve sample efficiency and reduce computational requirements for new tasks. However, representations used for transfer are usually generic, and are not tailored to a particular distribution of downstream tasks. We explore the use of expert representations for transfer with a simple, yet effective, strategy. We train a diverse set of experts by exploiting existing label structures, and use cheap-to-compute performance proxies to select the relevant expert for each target task. This strategy scales the process of transferring to new tasks, since it does not revisit the pre-training data during transfer. Accordingly, it requires little extra compute per target task, and results in a speed-up of 2-3 orders of magnitude compared to competing approaches. Further, we provide an adapter-based architecture able to compress many experts into a single model. We evaluate our approach on two different data sources and demonstrate that it outperforms baselines on over 20 diverse vision tasks in both cases.
Continuous Integration of Machine Learning Models with ease.ml/ci: Towards a Rigorous Yet Practical Treatment
Renggli, Cedric, Karlaลก, Bojan, Ding, Bolin, Liu, Feng, Schawinski, Kevin, Wu, Wentao, Zhang, Ce
Continuous integration is an indispensable step of modern software engineering practices to systematically manage the life cycles of system development. Developing a machine learning model is no difference - it is an engineering process with a life cycle, including design, implementation, tuning, testing, and deployment. However, most, if not all, existing continuous integration engines do not support machine learning as first-class citizens. In this paper, we present ease.ml/ci, to our best knowledge, the first continuous integration system for machine learning. The challenge of building ease.ml/ci is to provide rigorous guarantees, e.g., single accuracy point error tolerance with 0.999 reliability, with a practical amount of labeling effort, e.g., 2K labels per test. We design a domain specific language that allows users to specify integration conditions with reliability constraints, and develop simple novel optimizations that can lower the number of labels required by up to two orders of magnitude for test conditions popularly used in real production systems.
The Convergence of Sparsified Gradient Methods
Alistarh, Dan, Hoefler, Torsten, Johansson, Mikael, Konstantinov, Nikola, Khirirat, Sarit, Renggli, Cedric
Stochastic Gradient Descent (SGD) has become the standard tool for distributed training of massive machine learning models, in particular deep neural networks. Several families of communication-reduction methods, such as quantization, largebatch methods, and gradient sparsification, have been proposed to reduce the overheads of distribution. To date, gradient sparsification methods-where each node sorts gradients by magnitude, and only communicates a subset of the components, accumulating the rest locally-are known to yield some of the largest practical gains. Such methods can reduce the amount of communication per step by up to three orders of magnitude, while preserving model accuracy. Yet, this family of methods currently has no theoretical justification. This is the question we address in this paper. We prove that, under analytic assumptions, sparsifying gradients by magnitude with local error correction provides convergence guarantees, for both convex and non-convex smooth objectives, for data-parallel SGD. The main insight is that sparsification methods implicitly maintain bounds on the maximum impact of stale updates, thanks to selection by magnitude. Our analysis also reveals that these methods do require analytical conditions to converge well, justifying and complementing existing heuristics.
The Convergence of Sparsified Gradient Methods
Alistarh, Dan, Hoefler, Torsten, Johansson, Mikael, Konstantinov, Nikola, Khirirat, Sarit, Renggli, Cedric
Distributed training of massive machine learning models, in particular deep neural networks, via Stochastic Gradient Descent (SGD) is becoming commonplace. Several families of communication-reduction methods, such as quantization, large-batch methods, and gradient sparsification, have been proposed. To date, gradient sparsification methods--where each node sorts gradients by magnitude, and only communicates a subset of the components, accumulating the rest locally--are known to yield some of the largest practical gains. Such methods can reduce the amount of communication per step by up to \emph{three orders of magnitude}, while preserving model accuracy. Yet, this family of methods currently has no theoretical justification. This is the question we address in this paper. We prove that, under analytic assumptions, sparsifying gradients by magnitude with local error correction provides convergence guarantees, for both convex and non-convex smooth objectives, for data-parallel SGD. The main insight is that sparsification methods implicitly maintain bounds on the maximum impact of stale updates, thanks to selection by magnitude. Our analysis and empirical validation also reveal that these methods do require analytical conditions to converge well, justifying existing heuristics.