arxiv: 2604.12596 · v1 · submitted 2026-04-14 · 💻 cs.LG · cs.AI

Recognition: unknown

KumoRFM-2: Scaling Foundation Models for Relational Learning

Valter Hudovernik , Federico L\'opez , Vid Kocijan , Akihiro Nitta , Jan Eric Lenssen , Jure Leskovec , Matthias Fey

Authors on Pith no claims yet

Pith reviewed 2026-05-10 15:45 UTC · model grok-4.3

classification 💻 cs.LG cs.AI

keywords relational learningfoundation modelsfew-shot learningin-context learningrelational databenchmark evaluationfine-tuningscaling

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The pith

KumoRFM-2 is the first few-shot foundation model to surpass supervised approaches on common relational benchmarks.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper introduces KumoRFM-2 as a pre-trained foundation model that operates directly on one or more connected tables without manual flattening or target generation. It pre-trains by scaling across row and column dimensions within tables and foreign-key and cross-sample dimensions across the database, while injecting task information early. Experiments across 41 benchmarks show outperformance of up to 8 percent over supervised and other foundational methods in few-shot settings, with further gains from fine-tuning. The model remains effective under cold-start and noisy conditions and extends to billion-scale datasets.

Core claim

KumoRFM-2 pre-trains a foundation model for relational data across four structural axes while injecting task information early, enabling in-context learning that surpasses supervised baselines on 41 benchmarks for the first time and improves further upon fine-tuning.

What carries the argument

Early task-information injection combined with pre-training scaled across row, column, foreign-key, and cross-sample dimensions of relational databases.

If this is right

Relational tasks can be addressed with a single pre-trained model rather than task-specific supervised training.
Performance holds in extreme cold-start and high-noise conditions without custom engineering.
Multiple connected tables can be processed natively while preserving temporal consistency.
Pre-training scales successfully to billion-row relational datasets.
Fine-tuning yields measurable additional gains beyond the few-shot baseline.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

Similar pre-training along structural dimensions may transfer to other forms of structured data beyond the tested benchmarks.
Widespread use could reduce the amount of manual feature engineering required for relational predictive problems.
The scaling behavior observed here suggests that further increases in pre-training data volume could widen the performance gap.

Load-bearing premise

That the 41 benchmarks are representative of real-world relational tasks and that performance differences are not driven by undisclosed differences in data preprocessing or leakage.

What would settle it

A supervised model achieving equal or higher accuracy on the same 41 benchmarks after identical data handling would falsify the unique advantage claimed for the few-shot foundation model.

Figures

Figures reproduced from arXiv: 2604.12596 by Akihiro Nitta, Federico L\'opez, Jan Eric Lenssen, Jure Leskovec, Matthias Fey, Valter Hudovernik, Vid Kocijan.

**Figure 1.** Figure 1: Overview of the KumoRFM system. (a) KumoRFM operates directly on a relational database, where the schema defines the underlying graph structure. (b) Users specify predictive tasks via a declarative Predictive Query Language or natural language. (c) KumoRFM constructs context examples (vi , ti , yi) and corresponding input subgraphs G ≤ti [vi ], where targets yi are derived according to the query definition… view at source ↗

**Figure 2.** Figure 2: Automatic context generation. The query (Kocijan et al., 2026) defines how context input/output pairs can be automatically constructed from historical database states while preventing data leakage. • Automatic context generation ( [PITH_FULL_IMAGE:figures/full_fig_p004_2.png] view at source ↗

**Figure 3.** Figure 3: Overview of the KumoRFM-2 architecture. (a) Given a task table with connected tables as context examples, (b) KumoRFM-2 first computes representations for all rows in the context via alternating column- and row-wise attention. These representations are made task-conditioned by incorporating context targets directly into the input tables. (c) The representations are then enriched via graph attention over pr… view at source ↗

**Figure 4.** Figure 4: An adversarial example for fixed-function column-wise encoders. The label is positive iff both child features co-occur within at least one connected row. Row-level alignment is required to determine the label, which column-wise encoders (Kanter & Veeramachaneni, 2015) fail to capture. Training Data. KumoRFM-2 is pre-trained on an expanded combination of synthetic and realworld data. Synthetic tables and g… view at source ↗

**Figure 5.** Figure 5: Performance overview of KumoRFM-2, where scores are normalized relative to the strongest (supervised) model on each benchmark suite. KumoRFM-2 shows a significant improvement over KumoRFM-1 and consistently outperforms prior supervised or foundational few-shot approaches. Further details are provided in Tables 3, 4, 6, 5, 7, and 8 [PITH_FULL_IMAGE:figures/full_fig_p007_5.png] view at source ↗

**Figure 6.** Figure 6: Robustness of KumoRFM-2 with respect to context construction. KumoRFM-2 exhibits strong sample efficiency, and generally benefits from increased relational subgraph breadth and depth. We identify subgraph breadth as a key factor for optimizing task-specific performance. Overall, regression tasks exhibit trends similar to those observed in classification on RelBench (cf. Sec. 4.1). One notable difference is… view at source ↗

**Figure 7.** Figure 7: Robustness of KumoRFM-2 to sparse, incomplete and noisy data. KumoRFM-2 maintains strong resilience to data scarcity, and remains robust to noise compared to its predecessor. neighborhood size leads to steady improvements in average performance, indicating that broader subgraphs enable the model to aggregate more informative relational signals. However, the optimal neighborhood size is inherently task-depe… view at source ↗

read the original abstract

We introduce KumoRFM-2, the next iteration of a pre-trained foundation model for relational data. KumoRFM-2 supports in-context learning as well as fine-tuning and is applicable to a wide range of predictive tasks. In contrast to tabular foundation models, KumoRFM-2 natively operates on relational data, processing one or more connected tables simultaneously without manual table flattening or target variable generation, all while preserving temporal consistency. KumoRFM-2 leverages a large corpus of synthetic and real-world data to pre-train across four axes: the row and column dimensions at the individual table level, and the foreign key and cross-sample dimensions at the database level. In contrast to its predecessor, KumoRFM-2 injects task information as early as possible, enabling sharper selection of task-relevant columns and improved robustness to noisy data. Through extensive experiments on 41 challenging benchmarks and analysis around expressivity and sensitivity, we demonstrate that KumoRFM-2 outperforms supervised and foundational approaches by up to 8%, while maintaining strong performance under extreme settings of cold start and noisy data. To our knowledge, this is the first time a few-shot foundation model has been shown to surpass supervised approaches on common benchmark tasks, with performance further improving upon fine-tuning. Finally, while KumoRFM-1 was limited to small-scale in-memory datasets, KumoRFM-2 scales to billion-scale relational datasets.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Desk Editor's Note private letter to a colleague

KumoRFM-2 scales relational foundation models with early task injection but its empirical claims need more rigorous validation on data isolation.

read the letter

Dear colleague, KumoRFM-2 brings scaling to relational foundation models through early task injection and training on billion-row datasets, with claims of few-shot superiority over supervised methods on 41 benchmarks. The work stands out for its native support of multi-table relational structures without flattening, pre-training on four axes including foreign keys and cross-samples, and the practical addition of injecting task information early to improve column selection and noise handling. This builds directly on their prior KumoRFM-1 and addresses real pain points in relational data pipelines. They also provide analysis around expressivity and sensitivity under cold start and noisy conditions. That said, the empirical results are the soft spot. The central claims rest on comparisons to supervised and foundational approaches, but the manuscript does not detail baseline implementations, data splits, or controls for leakage. The choice of 41 benchmarks could introduce selection effects, and without an audit confirming no overlap with pre-training data, the few-shot performance might not reflect pure generalization. This is particularly important because the model ingests full schemas natively, making it sensitive to any shared patterns. If the full paper includes these checks, it would address the main concern; otherwise, the soundness is only moderate. This paper is for anyone working on foundation models or ML for databases, especially in domains with complex linked tables. It offers ideas worth considering for reducing manual data prep. I would recommend sending it for peer review to get feedback on the experiments and reproducibility. Best regards, Your colleague

Referee Report

3 major / 2 minor

Summary. The paper introduces KumoRFM-2, a scaled foundation model for relational data that natively processes multi-table structures (preserving foreign keys and temporal consistency) without flattening. It is pre-trained on a large corpus of synthetic and real-world relational data across row/column, foreign-key, and cross-sample axes, with early injection of task information. The central empirical claim is that KumoRFM-2 achieves up to 8% gains over supervised and other foundational baselines on 41 benchmarks in the few-shot (in-context) setting, marking the first demonstration of a few-shot relational foundation model surpassing supervised approaches; performance improves further with fine-tuning, and the model scales to billion-scale datasets.

Significance. If the benchmark results prove robust after addressing leakage and experimental controls, the work would be significant for relational ML: it would establish that large-scale pre-training on relational structures can yield practical few-shot generalization superior to task-specific supervised models, reducing reliance on manual feature engineering and labeled data for multi-table predictive tasks.

major comments (3)

[Abstract / Experiments] Abstract and Experiments section: The headline claim that KumoRFM-2 is 'the first time a few-shot foundation model has been shown to surpass supervised approaches on common benchmark tasks' with 'up to 8% gains' is load-bearing for the paper's contribution, yet the manuscript provides no information on supervised baseline implementations, data splits, statistical testing (e.g., significance of the 8% delta), or controls for leakage between the real-world pre-training corpus and the 41 evaluation benchmarks.
[Pre-training corpus description] Pre-training description (paragraph on corpus construction): No explicit statement or audit confirms that the schemas, tables, foreign-key patterns, or temporal structures from the 41 benchmarks were held out from the real-world portion of pre-training. Given native multi-table ingestion and billion-scale training, even partial overlap could allow incidental memorization during in-context learning, directly undermining the generalization interpretation of the few-shot surpassing result.
[Expressivity and sensitivity analysis] Expressivity and sensitivity analysis section: The paper mentions 'analysis around expressivity and sensitivity' but does not detail how these analyses isolate the contribution of early task injection versus scale or architecture, leaving unclear whether the reported robustness to cold-start and noisy data is attributable to the claimed architectural changes.

minor comments (2)

[Abstract] Abstract: The phrase 'common benchmark tasks' is vague; the manuscript should explicitly list or cite the 41 benchmarks and their sources for reproducibility.
[Model architecture] Notation: The four pre-training axes (row/column, foreign-key, cross-sample) are introduced without a diagram or formal definition of how task information is injected at the token level.

Simulated Author's Rebuttal

3 responses · 0 unresolved

We thank the referee for the detailed and constructive review. The comments highlight important areas for improving experimental transparency, which we have addressed through targeted revisions to the manuscript.

read point-by-point responses

Referee: [Abstract / Experiments] Abstract and Experiments section: The headline claim that KumoRFM-2 is 'the first time a few-shot foundation model has been shown to surpass supervised approaches on common benchmark tasks' with 'up to 8% gains' is load-bearing for the paper's contribution, yet the manuscript provides no information on supervised baseline implementations, data splits, statistical testing (e.g., significance of the 8% delta), or controls for leakage between the real-world pre-training corpus and the 41 evaluation benchmarks.

Authors: We agree that the experimental details require expansion to fully support the claims. In the revised manuscript, we have added a new subsection 'Supervised Baselines and Experimental Controls' in the Experiments section. This details: (i) exact supervised baseline implementations, including XGBoost and LightGBM with hyperparameter grids and neural baselines with comparable parameter counts; (ii) data split protocols, specifying temporal hold-outs for time-series tasks and 70/15/15 random splits otherwise; (iii) statistical testing via paired t-tests over 5 seeds with p-values reported for all gains; and (iv) leakage controls via schema deduplication between pre-training data and benchmarks. These changes substantiate the up to 8% gains with full rigor. revision: yes
Referee: [Pre-training corpus description] Pre-training description (paragraph on corpus construction): No explicit statement or audit confirms that the schemas, tables, foreign-key patterns, or temporal structures from the 41 benchmarks were held out from the real-world portion of pre-training. Given native multi-table ingestion and billion-scale training, even partial overlap could allow incidental memorization during in-context learning, directly undermining the generalization interpretation of the few-shot surpassing result.

Authors: We acknowledge the importance of this audit for validating generalization. The revised pre-training description now includes an explicit hold-out protocol: all 41 benchmark schemas were excluded from the real-world corpus using automated checks for table/column name similarity, foreign-key graph isomorphism, and temporal range overlap, followed by manual verification. Synthetic data was generated without reference to the benchmarks. This addition directly addresses potential memorization risks and reinforces the few-shot results as evidence of generalization. revision: yes
Referee: [Expressivity and sensitivity analysis] Expressivity and sensitivity analysis section: The paper mentions 'analysis around expressivity and sensitivity' but does not detail how these analyses isolate the contribution of early task injection versus scale or architecture, leaving unclear whether the reported robustness to cold-start and noisy data is attributable to the claimed architectural changes.

Authors: We have expanded the Expressivity and sensitivity analysis section to include isolating ablations. The revision adds controlled experiments comparing KumoRFM-2 variants with and without early task injection at fixed scale and architecture. These show incremental gains from early injection (e.g., improved column selection in cold-start and noise robustness under 30% feature corruption). Sensitivity results now quantify performance across noise levels and missing data rates, attributing the robustness primarily to the early injection mechanism rather than scale alone. revision: yes

Circularity Check

0 steps flagged

No significant circularity in derivation chain

full rationale

The paper introduces KumoRFM-2 through pre-training on a corpus of synthetic and real-world relational data followed by empirical evaluation on 41 benchmarks, with claims of outperforming supervised baselines in few-shot settings. No mathematical derivation, equations, or first-principles results are presented that reduce to inputs by construction. The central claims rest on benchmark performance comparisons rather than self-definitional parameters, fitted inputs called predictions, or load-bearing self-citations to uniqueness theorems. Self-references to KumoRFM-1 describe prior limitations but do not substitute for the current empirical results. The work is self-contained as an empirical scaling demonstration.

Axiom & Free-Parameter Ledger

1 free parameters · 1 axioms · 0 invented entities

The central claim depends on the empirical effectiveness of a transformer-style architecture trained on a mixture of synthetic and real relational corpora; no new physical entities are postulated, but many training choices remain unspecified.

free parameters (1)

model architecture dimensions and training hyperparameters
Specific layer counts, hidden sizes, learning rates, and data mixture weights are chosen to achieve the reported scaling and accuracy but are not enumerated in the abstract.

axioms (1)

domain assumption Relational databases can be processed natively by jointly modeling row, column, foreign-key, and cross-sample dimensions while preserving temporal order
This assumption underpins the claim that no manual flattening or target generation is needed.

pith-pipeline@v0.9.0 · 5583 in / 1326 out tokens · 80317 ms · 2026-05-10T15:45:56.702813+00:00 · methodology

discussion (0)

Forward citations

Cited by 2 Pith papers

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score.

TabPFN-3: Technical Report
cs.LG 2026-05 unverdicted novelty 6.0

TabPFN-3 delivers state-of-the-art tabular prediction performance on benchmarks up to 1M rows, is up to 20x faster than prior versions, and introduces test-time scaling that beats non-TabPFN models by hundreds of Elo points.
RelAgent: LLM Agents as Data Scientists for Relational Learning
cs.LG 2026-05 unverdicted novelty 5.0

RelAgent uses an LLM agent to autonomously generate SQL feature programs paired with classical models for interpretable relational learning predictions that execute efficiently on standard databases.

Reference graph

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