A LoRA adapter fine-tuned on Qwen2.5-Coder-7B-Instruct for translating natural language questions about DNA methylation into executable DuckDB SQL queries over the CpG Atlas database.

Model Description

This adapter enables researchers to query the CpG Atlas database — a centralized multi-layer knowledgebase covering 18 functional annotation layers across >1.2 million CpG sites — using plain English. The model was fine-tuned on domain-specific question-SQL pairs formatted in ChatML, where the system message contains relevant table schemas and column descriptions so the model learns to read and apply schema context at inference time.

Task: Natural Language to SQL (NL-to-SQL) for the CpG Atlas DuckDB database

Example input:

Find all CpGs associated with mortality that have ICC greater than 0.75 and are immune cell invariant

Example output:

sql

SELECT e.ProbeID, e.trait, e.beta, i.icc_sugden
FROM ewas_atlas e
JOIN icc_data i ON e.ProbeID = i.ProbeID
JOIN immune_invariant inv ON e.ProbeID = inv.ProbeID
WHERE e.trait LIKE '%mortality%'
AND i.icc_sugden > 0.75;

Training Details

Parameter	Value
Base model	Qwen/Qwen2.5-Coder-7B-Instruct
Method	LoRA (Low-Rank Adaptation)
Rank (r)	32
Alpha	64
Dropout	0.05
Target modules	q_proj, k_proj, v_proj, o_proj, gate_proj, up_proj, down_proj
Quantization	4-bit NF4 (double quantization, bfloat16 compute)
Epochs	5
Learning rate	1e-4
Scheduler	Cosine with 0.05 warmup ratio
Batch size	2 (with 8 gradient accumulation steps)
Max sequence length	4096
Optimizer	paged_adamw_32bit
Training examples	541
Validation examples	135
Hardware	NVIDIA A100/H100 GPU

Training loss converged from 1.62 to 0.005.

Evaluation

Evaluated on a held-out benchmark of 135 queries spanning five complexity classes: (1) simple single-table lookups, (2) multi-table joins, (3) filtering, (4) concept-mapping queries requiring biological synonym understanding, and (5) complex queries requiring additional analysis steps.

Model	Exact Accuracy	Accuracy (incl. partial)
Qwen2.5-Coder-7B-Instruct (base)	30%	86%
This model (fine-tuned)	61%	88%
GPT-5.4 mini (API mode)	80%	98%

Usage

With PEFT

python

from peft import PeftModel
from transformers import AutoModelForCausalLM, AutoTokenizer

base_model = AutoModelForCausalLM.from_pretrained(
    "Qwen/Qwen2.5-Coder-7B-Instruct",
    device_map="auto",
    torch_dtype="auto",
)
model = PeftModel.from_pretrained(base_model, "vandijklab/CpGAtlas-NL-to-SQL-Qwen2.5-Coder-7B-LoRA")
tokenizer = AutoTokenizer.from_pretrained("vandijklab/CpGAtlas-NL-to-SQL-Qwen2.5-Coder-7B-LoRA")

messages = [
    {"role": "system", "content": "You are an expert bioinformatics data engineer. Write one executable DuckDB SQL query to answer the question based on the schema. Return only SQL. Do not include markdown.\n\nSchema:\n{schema_context}"},
    {"role": "user", "content": "What transposable element classes are in the transposon dataset?"}
]

text = tokenizer.apply_chat_template(messages, tokenize=False, add_generation_prompt=True)
inputs = tokenizer(text, return_tensors="pt").to(model.device)
outputs = model.generate(**inputs, max_new_tokens=512)
print(tokenizer.decode(outputs[0][inputs.input_ids.shape[1]:], skip_special_tokens=True))

Self-Correcting Inference

The model is designed to be used with a self-correcting execution loop: the generated SQL is executed against DuckDB, and if execution fails, the error message is appended to the prompt for the model to revise its output (up to 3 retry attempts).

Intended Use

This model is intended for use with the CpG Atlas database and its associated schema. It is designed to support researchers in querying multi-dimensional DNA methylation annotations without requiring SQL expertise. The model can run entirely locally without an internet connection or API key.

Limitations

Trained on a specific query distribution over the CpG Atlas schema; may underperform on highly novel query patterns beyond its training scope
Users should inspect generated SQL before treating results as definitive
Requires sufficient computational resources to run a 7B parameter model (quantized inference requires ~6GB VRAM)

Citation

If you use this model, please cite the CpG Atlas paper (citation forthcoming).

Framework Versions

PEFT 0.12.0
Transformers (compatible with Qwen2.5)
TRL (SFTTrainer)