FINER-SQL-0.5B-BIRD

A small but capable 0.5 B-parameter Text-to-SQL model fine-tuned from griffith-bigdata/Qwen-2.5-Coder-0.5B-SQL-Writer with GRPO + the FINER-SQL dense rewards (Memory + Atomic).

50.85% Execution Accuracy on BIRD Dev (n=30, value-aware voting). Runs on a 4-8 GB GPU.

📄 See other models: https://huggingface.co/collections/griffith-bigdata/finer-sql 📄 GitHub: https://github.com/thanhdath/finer-sql/tree/main


FINER-SQL Model Family — Comparison Across All Sizes

Model Params BIRD Dev (n=30, vav) Spider Dev (n=30, vav, +agg_hint)
FINER-SQL-3B-BIRD 3 B 67.54% 83.8%
FINER-SQL-3B-Spider 3 B 63.04% 85.10%
FINER-SQL-0.5B-BIRD (this model) 0.5 B 50.85% 68.6%
FINER-SQL-0.5B-Spider 0.5 B TBD 75.0%

The 0.5 B family demonstrates that GRPO + FINER rewards scale down to deployment-friendly sizes while retaining most of the gain.


Inference

Quick start (vLLM)

from vllm import LLM, SamplingParams

llm = LLM(
    model="griffith-bigdata/FINER-SQL-0.5B-BIRD",
    dtype="bfloat16",
    max_model_len=4096,
    gpu_memory_utilization=0.7,
)

system_prompt = """You are a meticulous SQL expert. Generate a single, correct SQL query for the user question and the provided database schema.
Follow this exact response format:

Rules:
- Output exactly one SQL statement.
- The SQL must be executable on SQLite.
- Do not include any explanatory text.
- Output one SQL statement only. Do not include any extra text, tags, or code fences."""

sampling = SamplingParams(n=30, temperature=1.0, max_tokens=2048)
messages = [
    {"role": "system", "content": system_prompt},
    {"role": "user", "content": f"Database Schema:\n{schema}\n\nQuestion: {question}\n\nEvidence: {evidence}"},
]
output = llm.chat(messages, sampling)
candidate_sqls = [c.text.split("</think>")[-1].strip() for c in output[0].outputs]
# Apply majority voting (vav) — see GitHub repo

Recommended evaluation pipeline

  1. Generate n=30 candidates with temperature=1.0
  2. Execute each candidate; group results
  3. Pick from the largest non-empty success group (value-aware voting, "vav")
  4. Score with the official BIRD evaluator

This pipeline gives 50.85% MV on BIRD Dev V2 prompts (best 0.5 B result).


Detailed BIRD Dev results (V2 prompts, n=30, vav)

Difficulty Count Execution Accuracy
Simple 925 ~58%
Moderate 464 ~42%
Challenging 145 ~38%
All 1534 50.85%

Recall@30: 68.32% (any-correct rate among 30 candidates).


Cross-benchmark: this model on Spider Dev (zero-shot)

Setup Spider Official EX
Default 68.6%
FINER-SQL-0.5B-Spider (specialist) 75.0%

For Spider use-cases, the FINER-SQL-0.5B-Spider checkpoint is preferred (+6.4 pp).


Training

Parameter Value
Base model griffith-bigdata/Qwen-2.5-Coder-0.5B-SQL-Writer
Algorithm GRPO
Train data BIRD train (V2 prompts, top-30 GRAST)
Total steps 4000 (this checkpoint = 3000)
Learning rate 8e-6
Num generations per prompt 32
Gradient accumulation 32
Max completion length 2048
Max prompt length 2048
Temperature (rollout) 1.0
Selection during eval vav (value-aware voting)
Rewards Execution + Atomic + Memory + Format
Intrinsic Top-K 20 (ChromaDB)

License

Inherits the base model's license (Apache 2.0).


Citation

@article{finer-sql-2026,
  title  = {FINER-SQL: Fine-grained reasoning rewards for small Text-to-SQL models},
  author = {Thanh Dat and others},
  year   = {2026},
}
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