REVIEW 2 major objections 5 minor 3 cited by
Tackling prediction tasks in relational databases with LLMs
T0 review · 2 major / 5 minor · reviewed 2026-08-12 · deepseek-v4-flash
Pith's one-line read A frozen pretrained LLM that reads relational databases as nested JSON documents matches or slightly exceeds the relational deep learning baseline on RelBench classification, and comes within about 0.5 MAE on regression.
desk verdict Useful first LLM baseline for RelBench, but the headline competitiveness claim hinges on rel-f1 tasks where the model uses memorized knowledge; still deserves peer review with revisions. read the letter →
The pith
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
The reading
What carries the argument
The load-bearing object is the document construction procedure (Algorithm 1): for each entity, it recursively joins related tables via foreign keys, selects up to $n_{\mathrm{nest}}$ most recent rows from linked tables before the prediction timestamp, and nests them in JSON so the LLM does not need multi-hop reasoning to connect an entity to its history. Around this sits a metric-aware readout: for AUROC the positive-token probability is used directly, and for MAE a one-hidden-layer MLP head is trained on the frozen LLM's last-token embedding using at most $10^5$ documents. The procedure's role is to convert a heterogeneous relational database into a uniform text input that a pretrained model can score without any parameter updates to the LLM itself.
What would settle it
Recompute RelBench averages after removing the three rel-f1 tasks or after replacing driver, team, and race names with anonymous IDs before document construction; if the anonymized rel-f1 scores fall to near chance while the original documents score around 78–90 AUROC, or if the remaining average drops below RDL, the leakage channel is confirmed and the headline comparison must be revised.
Extended reading notes
Core claim
The central claim is that denormalizing a relational database into nested text documents is enough to make LLMs competitive with dedicated relational deep learning. The paper's procedure starts from a task-table row, follows foreign keys to primary keys, recursively pulls in up to $n_{\mathrm{nest}}$ related rows from linked tables up to depth $d$, prepends task and database descriptions plus in-context examples, and serializes everything as JSON with the target last. For binary classification the authors use the probability of the token "1" as the score (justified by AUROC's invariance to monotone transforms of $P(y=1\mid x)$), and for regression they train a small MLP on the LLM's token embeddings rather than using the median of sampled token probabilities, which performs poorly. The resulting frozen-model system matches or slightly exceeds the relational deep learning baseline on RelBench classification while remaining within about 0.5 MAE on regression, establishing LLM-based prediction as a new simple baseline.
Load-bearing premise
The comparison assumes the RelBench temporal split is the only gate on information: that test labels are not already inside the LLM's pretraining knowledge, which the paper itself undercuts by noting that on rel-f1 the models appear to lean on memorized Formula-1 facts.
Editorial extensions
If this is right
- A frozen pretrained LLM plus a small readout becomes a credible baseline for relational database prediction, competing with end-to-end relational deep learning.
- Because the MLP head needs only a subset of training documents (up to $10^5$) while several RelBench tasks have over a million training rows, the approach may pay off in low-data regimes.
- Which document parameters matter varies by task: some need many related examples, some need deeper nesting into linked tables, and zero-shot documents almost always fail, so context selection is the main lever.
- The modest gap between 1B and 3B models suggests document content, not model capacity, drives most of the gain.
- The same document construction extends in principle to non-text columns (images, audio) as multimodal foundation models mature.
Reading between the lines
- If test labels from rel-f1 are already memorized by the pretrained model, the headline average is inflated; a fair comparison would re-run the benchmark with entity names anonymized or rel-f1 excluded, and the gap over RDL may shrink or reverse.
- Because the MLP head reads a single hidden layer of embeddings, a cheaper linear-probe version of the method is a natural testable variant that would isolate how much relational signal survives in the frozen representations.
- Future benchmarks of this kind should include contamination checks, for example probing the base model on task rows stripped of all context, since a temporal split alone does not bound what a pretrained LLM already knows.
- A testable extension: use the LLM's own allocation of probability mass to select which in-context examples and nested rows to keep, reducing document length and cost instead of the current grid search.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. This paper proposes a simple LLM-based approach to RelBench relational prediction tasks. For each test entity, it constructs a JSON document containing a task description, up to ninc in-context examples, up to nrel related examples, and nested rows from linked tables up to depth d; a frozen Llama 3.2 base model then either scores the probability of the positive token (classification) or feeds its token embeddings to a small MLP head (regression and classification). The authors compare with LightGBM and Relational Deep Learning (RDL) on 21 RelBench tasks and report average AUROC 76.83/77.09 for the two LLM sizes with MLP heads versus 75.83 for RDL, and MAE 13.76/13.16 versus 12.63 for RDL.
Significance. If the competitiveness claim held, this would be a valuable new baseline: it avoids end-to-end graph training, can exploit a small training subset, and provides a clear algorithmic recipe. The paper is also unusually transparent in reporting the full per-configuration tables (Appendix D) and the algorithmic pseudocode. However, the headline result is contingent on the rel-f1 tasks, where the authors themselves suspect reliance on memorized factual knowledge; the contribution is therefore not yet established. The method is not presented with machine-checked proofs or code, but the algorithmic description is complete enough to replicate with reasonable effort.
major comments (2)
- [Section 4, Table 1] The rel-f1 results are not a fair test of the document-construction method because the models appear to rely on memorized Formula-1 knowledge. The authors write in Section 4 that the models 'seem to be mostly relying on their pre-existing factual knowledge of Formula-1'; the RelBench temporal split filters database rows (tv < tp) but cannot remove information from the LLM pretraining corpus. Recomputing Table 1 without driver-dnf and driver-top3 gives average AUROC 75.6 (1B+MLP) and 75.3 (3B+MLP) versus 76.2 for RDL, reversing the reported 76.8/77.1 versus 75.8 advantage. For regression, excluding driver-position changes the MAE gap from 1.13 to 1.33 (1B) and from 0.52 to 0.71 (3B) relative to RDL. On the remaining tasks the LLM+MLP variant is below RDL on 7 of 10 classification tasks and on most regression tasks, so the headline 'competitive to RDL' claim is not supported once the contaminated tasks are removed. The paper should either exclude rel-f1 from the headline averages or provide a leakage-controlled analysis (e.g., results on seasons or entities unlikely to be in pretraining, or a discussion of how many test labels are plausibly memorized).
- [Section 4 and Appendix D] The evaluation protocol selects, per task, the best of the document-parameter combinations on the validation set and then reports the test score of that single selection; Appendix D states 'For each set of document generation parameters, we conducted a single run.' Because there are no repeated seeds, bootstrap intervals, or other variance estimates, and because the test metric is computed on a random 10,000-example sample (Section 4) without a stated seed, the 0.5-1.3 point average differences in Table 1 cannot be distinguished from selection noise. The authors should report confidence intervals (e.g., repeated runs or bootstrap over test samples) and either fix the document parameters a priori or correct for selection over the grid.
minor comments (5)
- [Table 1] The header is ambiguous: each LLM column contains two numbers (metric-aware inference and +MLP) but the header only says 'Llama 3.2 1B + MLP' and 'Llama 3.2 3B + MLP'; please label the two subcolumns explicitly.
- [Algorithm 1] Line 13 of ADD_RELATED_ENTITIES returns X' rather than the updated X; this appears to be a typo, and the return value is never used by the caller.
- [Section 4] The grid over ninc, nrel, nnest, and d is described only in Appendix D; a compact statement of the grid in the main text would make the selection process easier to follow.
- [Limitations] The Limitations section should explicitly acknowledge the pretraining-leakage risk for rel-f1; currently it only mentions the single benchmark and context-length constraints.
- [Appendix C] The statement 'We will publish the code for replicating all the results' is not fulfilled in the manuscript; please provide a code link or state availability explicitly.
Circularity Check
No significant circularity: the LLM document-construction pipeline is benchmarked against external RelBench baselines, and no prediction is defined in terms of its fitted inputs.
full rationale
The paper's central claim—that serialized relational documents let LLMs perform competitively with Relational Deep Learning—is evaluated against external RelBench baselines from Robinson et al. (2024), not against a quantity derived from its own fitted parameters. The document-generation procedure constructs test inputs from database rows with tv < tp and appends the target only to training in-context examples, so the test prediction is not built from the target by construction. The MLP head is trained on a subset of generated training documents and selected via a validation set, which is standard supervised evaluation rather than a fitted parameter renamed as a prediction. The metric-aware inference argument relies on external statistical results (cross-entropy minimization, AUROC monotone transforms, MAE median), not on a self-citation. The paper's own observation that on rel-f1 the models 'seem to be mostly relying on their pre-existing factual knowledge of Formula-1' (Section 4) identifies a pretraining-data contamination risk for benchmark validity, but that is an evaluation confound, not a circular derivation: the test labels are not fed into the document construction or the model's inference procedure. No load-bearing step reduces to its own input or to a self-citation chain, so the circularity score is 0.
Assumptions & free parameters
free parameters (6)
- ninc (number of in-context examples) =
0, 8, or 16, selected per task on validation
- nrel (number of related examples) =
0, 8, or 16, selected per task on validation
- nnest (number of nested rows) =
0, 4, or 8, selected per task on validation
- d (relation graph traversal depth) =
0 or 1, selected per task on validation
- ntrain (MLP training subset size) =
1e4 or 1e5 examples, selected per task
- MLP hyperparameters =
hidden size 10, lr 1e-4, weight decay 1e-3, 100 epochs
assumptions (5)
- domain assumption A base LLM trained only with next-token prediction, under an unrestricted hypothesis class, models the true conditional distribution P(y|x).
- domain assumption JSON serialization of denormalized related rows preserves enough information for prediction and reduces multi-hop reasoning failures.
- domain assumption The RelBench temporal split (only rows with tv < tp may be used) prevents information leakage during LLM evaluation.
- standard math Optimal decision rules for AUROC and MAE justify metric-aware inference: any monotone transform of P(y=1|x) for AUROC, and the median for MAE.
- domain assumption The random 10,000-example test sample is representative, and single runs per parameter configuration are sufficient for the reported comparisons.
Cite this review
Pith. "Pith review of Tackling prediction tasks in relational databases with LLMs." pith.science (2026). https://pith.science/paper/M3ZIGKLC
@misc{pith2026241111829,
author = {Pith},
title = {Pith review of: Tackling prediction tasks in relational databases with LLMs},
year = {2026},
howpublished = {\url{https://pith.science/paper/M3ZIGKLC}},
note = {Machine review of arXiv:2411.11829}
}
read the original abstract
Though large language models (LLMs) have demonstrated exceptional performance across numerous problems, their application to predictive tasks in relational databases remains largely unexplored. In this work, we address the notion that LLMs cannot yield satisfactory results on relational databases due to their interconnected tables, complex relationships, and heterogeneous data types. Using the recently introduced RelBench benchmark, we demonstrate that even a straightforward application of LLMs achieves competitive performance on these tasks. These findings establish LLMs as a promising new baseline for ML on relational databases and encourage further research in this direction.
Figures
Forward citations
Cited by 3 Pith papers
-
Parameter-Free Encoders Remain Viable for RDB Foundation Models
Trainable RDB encoders cannot robustly exploit neighborhood labels as fixed foundation-model features or feature-importance signals, so simple parameter-free encoders stay near-SOTA.
-
No Need to Train Your RDB Foundation Model
Column-wise, parameter-free JUICE encodings let single-table ICL models solve multi-table RDB prediction tasks with no training or fine-tuning.
-
RelGNN: Composite Message Passing for Relational Deep Learning
RelGNN passes messages along schema-derived atomic routes through junction tables and improves over heterogeneous GNN baselines on most RelBench tasks, with the largest gain on one trial-database regression task.
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Reviewed August 12, 2026 · model on record in the stance chip above.
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