🚀 Alpha-SQL: Zero-Shot Text-to-SQL using Monte Carlo Tree Search

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📖 Introduction

Text-to-SQL, which enables natural language interaction with databases, serves as a pivotal method across diverse industries. With new, more powerful large language models (LLMs) emerging every few months, fine-tuning has become incredibly costly, labor-intensive, and error-prone. As an alternative, zero-shot Text-to-SQL, which leverages the growing knowledge and reasoning capabilities encoded in LLMs without task-specific fine-tuning, presents a promising and more challenging direction.

To address this challenge, we propose Alpha-SQL, a novel approach that leverages a Monte Carlo Tree Search (MCTS) framework to iteratively infer SQL construction actions based on partial SQL query states. To enhance the framework's reasoning capabilities, we introduce LLM-as-Action-Model to dynamically generate SQL construction actions during the MCTS process, steering the search toward more promising SQL queries. Moreover, Alpha-SQL employs a self-supervised reward function to evaluate the quality of candidate SQL queries, ensuring more accurate and efficient query generation.

📁 Project Structure

AlphaSQL/
├── 📂 data/
│   └── 📂 bird/
│       └── 📂 dev/
│           ├── 📄 dev.json
│           └── 📂 dev_databases/
├── 📂 config/
│   ├── 📄 qwen7b_sds_exp.yaml
│   └── 📄 qwen32b_bird_dev.yaml
├── 📂 results/
│   └── 📄 dev_pred_sqls.json
├── 📂 script/
│   ├── 📄 preprocess.sh
│   ├── 📄 qwen32b_bird_dev_exp.sh
│   ├── 📄 qwen7b_sds_exp.sh
│   └── 📄 sql_selection.sh
├── 📂 alphasql/
│   ├── 📂 runner/
│   │   ├── 📄 preprocessor.py
│   │   ├── 📄 sql_selection.py
│   │   ├── 📄 mcts_runner.py
│   │   ├── 📄 selection_runner.py
│   │   └── 📄 task.py
│   ├── 📂 templates/
│   │   ├── 📄 schema_selection.txt
│   │   ├── 📄 sql_revision.txt
│   │   ├── 📄 sql_generation.txt
│   │   ├── 📄 raphrase_question.txt
│   │   ├── 📄 identify_column_functions.txt
│   │   ├── 📄 identify_column_values.txt
│   │   └── 📄 keywords_extraction.txt
│   ├── 📂 config/
│   │   └── 📄 mcts_config.py
│   ├── 📂 database/
│   │   ├── 📄 sql_execution.py
│   │   ├── 📄 utils.py
│   │   ├── 📄 sql_parse.py
│   │   ├── 📄 schema.py
│   │   ├── 📄 database_manager.py
│   │   └── 📄 lsh_index.py
│   ├── 📂 llm_call/
│   │   ├── 📄 cost_recoder.py
│   │   ├── 📄 openai_llm.py
│   │   └── 📄 prompt_factory.py
│   └── 📂 algorithm/
│       ├── 📂 selection/
│       │   └── 📄 utils.py
│       └── 📂 mcts/
│           ├── 📄 mcts_node.py
│           ├── 📄 mcts_action.py
│           ├── 📄 mcts.py
│           └── 📄 reward.py
├── 📄 README.md
├── 📄 requirements.txt
└── 📄 .env

📥 Dataset Preparation

1. Download required resources:

   • Bird dataset: Bird Official Website

2. Unzip the dataset to data/bird directoty following the project structure above.

🛠️ Environment Setup

1. AlphaSQL Env

   conda create -n alphasql python=3.11
   conda activate alphasql
   
   pip install -r requirements.txt

2. VLLM Env

   conda create -n vllm python=3.12 -y
   conda activate vllm
   
   git clone https://github.com/vllm-project/vllm.git
   cd vllm
   pip install -e .

🚀 Deploy Local LLM Using VLLM

conda activate vllm

# For 4 GPUs
CUDA_VISIBLE_DEVICES=0,1,2,3 vllm serve Qwen/Qwen2.5-Coder-32B-Instruct --served-model-name Qwen/Qwen2.5-Coder-32B-Instruct --port 9999 -tp 4

# For 8 GPUs
CUDA_VISIBLE_DEVICES=0,1,2,3,4,5,6,7 vllm serve Qwen/Qwen2.5-Coder-32B-Instruct --served-model-name Qwen/Qwen2.5-Coder-32B-Instruct --port 9999 -tp 8

🏃‍♂️Run AlphaSQL

1. Switch AlphaSQL Conda Env

conda activate alphasql

2. Dataset Preprocessing

1. Configure your .env file based on env.example:

   # Required: OpenAI API Configuration (for LLM)
   OPENAI_API_KEY=your-api-key
   OPENAI_BASE_URL=https://api.openai.com/v1  # Or your custom endpoint
   
   # Required: Embedding Model Configuration
   EMBEDDING_MODEL=text-embedding-3-large  # Or text-embedding-3-small, text-embedding-ada-002
   
   # Optional: Separate embedding service (if using different base URL or API key)
   # EMBEDDING_API_KEY=your-embedding-api-key
   # EMBEDDING_BASE_URL=https://api.openai.com/v1  # or http://localhost:8080/v1

   Important Note:

   • If your embedding model uses a different base URL than your LLM, configure EMBEDDING_BASE_URL and EMBEDDING_API_KEY separately
   • If not set, embedding will automatically use OPENAI_BASE_URL and OPENAI_API_KEY
   • Example: LLM uses local VLLM (http://localhost:9999/v1), embedding uses OpenAI API (https://api.openai.com/v1)
   • See EMBEDDING_CONFIG.md for detailed configuration examples

2. Run the following:

   bash script/preprocess.sh

3. Generate SQL Candidates

1. Modify OPENAI_API_KEY and OPENAI_BASE_URL in .env file (we need to access Qwen/Qwen2.5-Coder-32B-Instruct model of VLLM delopyment)

   OPENAI_API_KEY="EMPTY"
   OPENAI_BASE_URL="http://0.0.0.0:9999/v1"

2. Run the following:

   bash script/qwen32b_bird_dev_exp.sh

4. Select Final SQL

1. Run the following:

   bash script/sql_selection.sh

2. The final pred_sqls.json will in the project root dir (defined in script/sql_selection.sh OUTPUT_PATH variable)

📝 Citation

If you find our work useful or inspiring, please kindly cite:

@inproceedings{alpha-sql,
  author       = {Boyan Li and
                  Jiayi Zhang and
                  Ju Fan and
                  Yanwei Xu and
                  Chong Chen and
                  Nan Tang and
                  Yuyu Luo},
  title        = {Alpha-SQL: Zero-Shot Text-to-SQL using Monte Carlo Tree Search},
  booktitle    = {Forty-Second International Conference on Machine Learning, {ICML} 2025,
                  Vancouver, Canada, July 13-19, 2025},
  publisher    = {OpenReview.net},
  year         = {2025}
}