REVIEW 4 major objections 4 minor 8 cited by
Synthetic relational databases, generated from scratch, unlock power-law scaling for relational foundation models and improve real-world predictions.
Reviewed by Pith at T0; open to challenge. T0 means a machine referee read the full paper against a public rubric. the ladder, T0–T4 →
T0 review · deepseek-v4-flash
2026-08-03 04:46 UTC pith:CDAQLDRN
load-bearing objection Worth engaging: PLUREL is a real from-scratch synthetic relational database generator, the scaling-law fits are honest but describe the generator prior, and the real-data transfer evidence is suggestive rather than conclusive. the 4 major comments →
PluRel: Synthetic Data unlocks Scaling Laws for Relational Foundation Models
The pith
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
On its own terms, the paper claims that relational foundation model pretraining loss obeys separable power laws in database diversity and token count: L(N)=A_N N^{-alpha_N}+C_N and L(S)=A_S S^{-alpha_S}+C_S. Using PLUREL to generate databases at scale, the authors fit these laws on up to 1024 databases and 32B tokens, hold out the largest points, and show that extrapolation predicts loss at 2x data scale. They further show that scaling the number of synthetic databases consistently lowers validation loss on real-world tasks and improves zero-shot AUROC and R², and that synthetic pretraining followed by continued pretraining on real data outperforms real-data-only pretraining on the majority
What carries the argument
PLUREL is a three-stage generative pipeline: (1) schemas are sampled from directed acyclic graph priors (e.g., Barabasi-Albert, random trees, Watts-Strogatz); (2) primary–foreign key connectivity between rows is modeled with hierarchical stochastic block models, creating clustered, event-like dependencies; (3) table features are generated by structural causal models whose source nodes carry temporal trend/cycle/noise inputs and whose mechanisms project parent values into a shared latent space before reconstructing numeric or categorical cells. This pipeline is CPU-only and lightweight, and each database is controlled by a scalar seed, so arbitrarily many diverse databases can be generated fo
Load-bearing premise
The load-bearing premise is that PLUREL's hand-chosen generator prior—DAG-only schemas, hierarchical-block foreign keys, and SCM features with the hyperparameter ranges listed in Table 2—is representative enough of real relational databases that scaling behavior measured on held-out synthetic data transfers to real-world data; this is verified only indirectly through 18 real tasks, with no coverage or distribution-shift analysis.
What would settle it
Train a relational foundation model under PLUREL at 2048 or 4096 synthetic databases and 64B tokens; if the measured validation loss clearly deviates from the fitted power-law line, the claimed scaling law is falsified. Alternatively, if a synthetic-only model trained on a much larger and more diverse corpus fails to improve (or worsens) zero-shot AUROC and R² on the same real tasks, the claim that synthetic diversity transfers to real data is called into question.
If this is right
- Scaling both diversity and size matters: increasing the number of databases while fixing tokens, or tokens while fixing databases, leads to non-monotonic loss; the two axes must be scaled together.
- The fitted power laws extrapolate reasonably to held-out larger scales (2x beyond the training grid), suggesting predictable returns from more synthetic data.
- Increasing the number of synthetic databases improves zero-shot performance on real-world relational tasks, indicating transfer from synthetic to real data.
- Synthetic pretraining is a useful warm start: continued pretraining on real data from a synthetic checkpoint beats real-data-only pretraining on average, with the largest gains on regression tasks.
- Synthetic-only pretraining is insufficient on its own; models trained only on synthetic data underperform real-data-only baselines on most tasks, so real-data alignment is still needed.
Where Pith is reading between the lines
- If the scaling laws hold beyond the tested grid, synthetic generation could become the standard pretraining corpus for relational foundation models, bypassing privacy constraints that currently block data sharing.
- The three-stage design invites ablation experiments: isolating the effect of schema topology, foreign-key clustering, or temporal structure on the fitted exponents could reveal which aspects of relational data most drive downstream transfer.
- A direct testable extension is widening the generator prior to include cyclic schemas, self-referencing foreign keys, or text columns; the paper already identifies these as unsupported, so measuring whether the power-law exponents change would sharpen the theory.
- The non-monotonic behavior when one axis is fixed suggests a compute-optimal frontier analogous to language-model scaling; fitting a joint scaling law with interaction terms could yield a principled recipe for allocating tokens across synthetic databases.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The paper introduces PLUREL, a three-stage generator for synthetic relational databases: (1) schema graphs sampled from DAG priors, (2) row-level primary–foreign key connectivity via hierarchical stochastic block models, and (3) feature values generated by table-wise Structural Causal Models with temporal exogenous inputs. The authors pretrain a Relational Transformer (RT) on up to 1024 synthetic databases and 32B tokens, and report two scaling laws: pretraining loss L(N) = A_N N^{-α_N} + C_N and L(S) = A_S S^{-α_S} + C_S (Eqs. 6-7). They further report that models pretrained on larger/more diverse synthetic corpora achieve lower MTP loss and better zero-shot AUROC/R² on 18 RelBench tasks, and that continued pretraining on real data from a synthetic checkpoint improves over real-only pretraining by +1.2 AUROC and +3.0 R² on average (Table 1). The main positive results are the synthetic-data scaling curves and the continued-pretraining gains, while the main limitation is that the scaling laws are established only on data from the hand-designed PLUREL prior.
Significance. If the transfer claims hold, this is a significant contribution: it attacks the data bottleneck for relational foundation models and provides a lightweight, reproducible synthetic-data pipeline. The paper is unusually thorough on compute: 56 pretraining runs, a held-out extrapolation point for each scaling curve, standard errors for the main results (App. D.1), and a robustness check with an alternative base model. The code, models, and data are released, and the authors are explicit about limitations (no cycles/self-loops, no text, no formal proofs). The main risk is that the scaling laws are fit to the synthetic prior and their connection to real-world behavior is only qualitative; the paper's own Figure 4c shows saturation and non-monotonicity on real data. This does not invalidate the synthetic-data findings, but it does mean the central 'unlocks scaling laws' claim needs either a quantitative transfer analysis or a more careful rephrasing.
major comments (4)
- [Sec. 3.1 (Eqs. 6-7) and Fig. 4] The scaling laws in Eqs. (6)-(7) are fit to held-out synthetic RDBs sampled from the same PLUREL generator. The abstract's claim that scaling N improves generalization to real databases is supported only by Fig. 4, where the real-data validation loss saturates and is non-monotonic for N∈{8,16,32} (the authors attribute this to RelBench being out-of-distribution, Sec. 3.2). This leaves open the possibility that the laws describe the generator rather than relational data in general. Please provide a direct transfer test: fit the same power-law form to the real-data loss from Fig. 4c and compare exponents, or at least report the correlation between synthetic held-out loss and real-data loss across the grid. If that is not possible, the abstract/conclusion should separate the synthetic scaling law from the qualitative transfer result.
- [Sec. 3.1 and Fig. 1] The power-law fits use 6-7 points with no uncertainty intervals on A_N, α_N, C_N (and similarly for S). Because L(N)=min_S L(N,S) is taken over a discrete 8×7 grid, each frontier point for N depends on a single S value; grid sparsity can materially change the fitted exponents. The held-out extrapolation to N=1024/S=32B (2× the fitted range) is reported without confidence bands. Please provide bootstrap or profile-likelihood intervals for the parameters, report the full L(N,S) table or surface, and state how many grid points determine each frontier point.
- [Sec. 3.3 and Table 1] The base model for continued pretraining (1024 RDBs, 4B tokens) is selected post hoc to maximize the worst validation metric (Sec. 3.3). Although App. D.1 reports robustness with one alternative base (512 RDBs, 32B tokens), the selection rule is not prespecified and the main table reports only the selected model. Please report the distribution of synthetic+real gains over all scaling checkpoints, or a prespecified selection rule, to quantify selection bias.
- [Appendix A and Table 2] PLUREL excludes self-loops/cycles (e.g., rel-stack posts.ParentID) and text/semantic columns, and the authors themselves connect this to performance drops (Sec. 3.3: 'lack of textual information and column semantics'). Because the transfer claim rests on representativeness of the prior, this limitation should be quantified (e.g., what fraction of RelBench schemas contain cycles/self-loops or text columns) and discussed as a boundary condition of the scaling law, not only in the appendix.
minor comments (4)
- [Sec. 2.3.2, Eq. (5)] The set M(i) is defined, but Eq. (5) uses |P(i)| in the sum index. Should be |M(i)|, or P(i) must be defined.
- [Appendix B.1] Typo: 'W A graphs' should be 'WS graphs' (Watts-Strogatz).
- [Table 2] Watts-Strogatz rewire probability is listed as 'constant uniform [0.1, 0.3]'. This is contradictory; it should be 'uniform'.
- [Sec. 3.2 and Fig. 4c] The statement that the loss 'saturates' should be quantified (e.g., plateau threshold or slope), since the same figure shows non-monotonic behavior for small N.
Circularity Check
Scaling laws are empirical fits with held-out extrapolation and external RelBench validation; no circular reduction found.
full rationale
The paper's central claims (Eqs. 6-7) are power-law fits to measured validation losses, not quantities defined into existence. Section 3.1 explicitly fits A_N, alpha_N, C_N on 7 (N, L(N)) points and the size-law parameters on 6 (S, L(S)) points while keeping N=1024 and S=32B held out, so those points are genuine extrapolations under the assumed functional form rather than predictions forced by construction. The transfer claim is tested against an external benchmark: 18 RelBench tasks not drawn from the PLUREL prior (Section 3.2, Table 1), with mean AUROC/R2 gains reported over real-only baselines. The principal self-citations (RT architecture, leave-one-DB-out protocol, and the Hudovernik et al. 2025 observation motivating HSBM connectivity) are background or methodological references and do not force the scaling result; no uniqueness theorem is imported and no fitted parameter is renamed as a prediction. The paper also admits limitations: Appendix A excludes self-loops and cyclic schemas, and Figure 4c shows saturation attributed to RelBench being out-of-distribution. These are external-validity and prior-representativeness concerns, not circularity; they may weaken the generality of the scaling law but do not make the derivation equivalent to its own inputs. A caveat remains that if the hand-specified PLUREL prior is unrepresentative, the measured scaling behavior describes PLUREL rather than real-world RDBs, but this is a generalization risk, not a circular reduction.
Axiom & Free-Parameter Ledger
free parameters (9)
- Schema graph prior families =
uniform {Barabasi-Albert, Reverse Random-Tree, Watts-Strogatz}
- Table, row, and column metadata ranges =
tables [3,20]; entity rows [500,1000]; activity rows [2000,5000]; columns power-law [3,40]; NULL rate [0.01,0.1]
- SCM causal graph prior and feature-node fraction =
uniform {Layered, Erdos-Renyi, Barabasi-Albert, Random-Tree, Reverse Random-Tree}; feature node % [0.3,0.9]
- MLP and embedding hyperparameters =
hidden dim 32, depth 2, activations {relu, elu, silu, softsign, tanh}, multiple initializations
- Exogenous input prior =
Beta(0.5,0.5), Beta(2,2), Beta(2,3), Beta(2,4), Beta(4,1); edge weights N(0,1)
- HSBM connectivity parameters =
levels [1,5]; blocks per level [1,3]; diagonal 0.9, off-diagonal U(0.001,0.002)
- Temporal pattern parameters =
trend exponent [0,2]; scales -1,1; cycle frequencies {0.1,...,1.0}; noise scales 0.05/1.0
- Scaling-law constants =
A_N, alpha_N, C_N, A_S, alpha_S, C_S (fit in Fig. 1)
- RT pretraining hyperparameters =
12 layers, batch 128, context 1024, BFS width 128, lr 5e-4, weight decay 0.1, warmup 0.2
axioms (6)
- ad hoc to paper Power-law functional forms L(N)=A_N N^-alpha_N + C_N and L(S)=A_S S^-alpha_S + C_S hold for RFM pretraining on PLUREL data.
- domain assumption Validation loss on held-out synthetic RDBs is a meaningful proxy for RFM capability and real-world generalization.
- domain assumption DAG-only schemas, with no cycles or self-loops, cover enough real relational structure.
- domain assumption HSBM hierarchies and SCM causal mechanisms capture the multi-scale dependencies RFMs need.
- domain assumption Row indices as primary keys and abstract column names do not block transfer to semantically named real tables.
- domain assumption Temporal exogenous inputs (trend, cycle, fluctuation) are sufficient to model row correlations.
read the original abstract
Relational Foundation Models (RFMs) facilitate data-driven decision-making by learning from complex multi-table databases. However, the diverse relational databases needed to train such models are rarely public due to privacy constraints. While there are methods to generate synthetic tabular data of arbitrary size, incorporating schema structure and primary-foreign key connectivity for multi-table generation remains challenging. Here we introduce PLUREL, a framework to synthesize multi-tabular relational databases from scratch. In a step-by-step fashion, PLUREL models (1) schemas with directed graphs, (2) inter-table primary-foreign key connectivity with bipartite graphs, and, (3) feature distributions in tables via conditional causal mechanisms. The design space across these stages supports the synthesis of a wide range of diverse databases, while being computationally lightweight. Using PLUREL, we observe for the first time that (1) RFM pretraining loss exhibits power-law scaling with the number of synthetic databases and total pretraining tokens, (2) scaling the number of synthetic databases improves generalization to real databases, and (3) synthetic pretraining yields strong base models for continued pretraining on real databases. Overall, our framework and results position synthetic data scaling as a promising paradigm for RFMs.
Figures
Forward citations
Cited by 8 Pith papers
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Reference graph
Works this paper leans on
-
[1]
When pretrained using synthetic data followed by real data, the model consistently improves upon the performance of RT trained solely on real data
We report the mean and standard error across three random seeds. When pretrained using synthetic data followed by real data, the model consistently improves upon the performance of RT trained solely on real data. On certain tasks, we observe slight degradations in performance. Notably, these tasks align with those for which the original authors report per...
2025
-
[2]
Parameter Kind Sampling Choices Database Schema graph priors (PG)set uniform{Barabasi-Albert, Reverse Random-Tree, Watts-Strogatz} Num tablesrange uniform [3, 20] Num rows (entity tables)range uniform [500, 1000] Num rows (activity tables)range uniform [2000, 5000] Num columnsrange power-law [3, 40] Min timestampconstant-1990-01-01 Max timestampconstant-2...
2000
-
[4]
Gueye, M., Attabi, Y ., and Dumas, M
URL https://arxiv.org/ abs/2511.08667. Gueye, M., Attabi, Y ., and Dumas, M. Row conditional-tgan for generating synthetic relational databases. InICASSP 2023-2023 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP), pp. 1–5. IEEE,
Pith/arXiv arXiv 2023
-
[5]
R., Pawar, S
Henry, A., Dachapally, P. R., Pawar, S. S., and Chen, Y . Query-key normalization for transformers. InFindings of the Association for Computational Linguistics: EMNLP 2020, pp. 4246–4253,
2020
-
[6]
Relational data generation with graph neural networks and latent diffusion models
Hudovernik, V . Relational data generation with graph neural networks and latent diffusion models. InNeurIPS 2024 Third Table Representation Learning Workshop,
2024
-
[8]
Ma, J., Thomas, V ., Hosseinzadeh, R., Labach, A., Cress- well, J
URL https://arxiv.org/ abs/2412.19437. Ma, J., Thomas, V ., Hosseinzadeh, R., Labach, A., Cress- well, J. C., Golestan, K., Yu, G., Caterini, A. L., and V olkovs, M. TabDPT: Scaling tabular foundation models on real data. InThe Thirty-ninth Annual Conference on Neural Information Processing Systems,
-
[9]
Robinson, J., Ranjan, R., Hu, W., Huang, K., Han, J., Dobles, A., Fey, M., Lenssen, J
URL https://arxiv.org/abs/ 2510.06377. Robinson, J., Ranjan, R., Hu, W., Huang, K., Han, J., Dobles, A., Fey, M., Lenssen, J. E., Yuan, Y ., Zhang, Z., et al. Relbench: A benchmark for deep learning on relational databases.Advances in Neural Information Processing Systems, 37:21330–21341,
-
[10]
URL https://arxiv.org/abs/2505. 15668. Schambach, M., Paul, D., and Otterbach, J. Scaling ex- periments in self-supervised cross-table representation learning. InNeurIPS 2023 Second Table Representation Learning Workshop,
2023
-
[11]
URL https://arxiv.org/ abs/2405.09818. Team, G., Kamath, A., Ferret, J., Pathak, S., Vieillard, N., Merhej, R., Perrin, S., Matejovicova, T., Ram ´e, A., Rivi`ere, M., et al. Gemma 3 technical report,
-
[12]
URL https://arxiv.org/abs/2503.19786. Wang, M., Gan, Q., Wipf, D., Zhang, Z., Faloutsos, C., Zhang, W., Zhang, M., Cai, Z., Li, J., Mao, Z., et al. 4dbinfer: A 4d benchmarking toolbox for graph-centric predictive modeling on rdbs.Advances in Neural Infor- mation Processing Systems, 37:27236–27273,
-
[13]
Zhai, X., Kolesnikov, A., Houlsby, N., and Beyer, L
URL https://arxiv.org/ abs/2505.09388. Zhai, X., Kolesnikov, A., Houlsby, N., and Beyer, L. Scaling vision transformers. InProceedings of the IEEE/CVF conference on computer vision and pattern recognition, pp. 12104–12113,
-
[15]
The binary mask M∈ {0,1}n×n specifies allowable token interactions, with M[q, k] = 1indicating that token q can attend to token k
(9) Here Q,K∈R n×dk and V∈R n×dv denote the query, key, and value matrices, wheren is the context length. The binary mask M∈ {0,1}n×n specifies allowable token interactions, with M[q, k] = 1indicating that token q can attend to token k. For example, causal language models use Mcausal[q, k] =1{k≤q} .Column Attention.Restricts attention to tokens within the...
2025
-
[2020]
URL https://arxiv.org/abs/2001. 08361. Kent, W. Consequences of assuming a universal relation. ACM Transactions on Database Systems (TODS), 6(4): 539–556,
2001
-
[2022]
Cai, K., Xiao, X., and Cormode, G
URL https://arxiv.org/ abs/2108.07258. Cai, K., Xiao, X., and Cormode, G. Privlava: synthesizing relational data with foreign keys under differential privacy. Proceedings of the ACM on Management of Data, 1(2): 1–25,
-
[2023]
URL https://arxiv.org/abs/2303.08774. Barab´asi, A.-L. and Albert, R. Emergence of scaling in random networks.science, 286(5439):509–512,
-
[2024]
and suggesting that post-hoc model selection would be ideal. D.2. Architectural Improvements: Query-Key Normalization The RT architecture supports multi-modal input representations for text, numeric, and boolean cell tokens, with type-specific encoders. During synthetic pretraining with such multi-modal(type) input tokens, we observed that zero-shot gener...
2020
-
[2025]
URL https://arxiv.org/abs/ 2405.13396. Dove, E. S. and Phillips, M. Privacy law, data sharing policies, and medical data: a comparative perspective. In Medical data privacy handbook, pp. 639–678. Springer,
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