---
title: "LLM Routing for Text-to-SQL | Tiaan van Antwerpen"
description: "An LLM routing orchestration framework for NL2SQL agentic workflows. My MEng research, released open source."
url: "https://tiaanvanantwerpen.com/projects/llm-routing-nl2sql"
type: "project"
author: "Tiaan van Antwerpen"
updated: "2026-10-01"
---

# LLM Routing for Text-to-SQL

> An LLM routing orchestration framework for NL2SQL agentic workflows. My MEng research, released open source.

## project

- by: Tiaan van Antwerpen (https://tiaanvanantwerpen.com/)
- years: 2024–2025
- code: https://github.com/tiaan720/LLM-routing-for-agentic-NL2SQL
- stack: Python, LangChain, LangGraph, MLflow, Vertex AI, Anthropic, OpenAI, PostgreSQL

## what it is

I built an LLM routing orchestration framework for academic research on NL2SQL agentic workflows, implementing three routing strategies: a Matrix Router based on a neural network, a RAG Router, and a Supervisor Agent Router.

The framework integrates MLflow for performance tracking with custom SQL accuracy metrics, and supports models from Vertex AI, Anthropic, OpenAI and local deployments.

It was evaluated across 13 LLMs. The RAG Router landed on the cost-performance Pareto front: on the 78 hold-out questions it scored higher on combined quality than the most expensive model, Claude Opus 4, at 56 times lower cost, $0.31 against $17.40, and ran three times faster. The framework is released as open source.

## highlights

- Three routing strategies: Matrix Router (neural network), RAG Router, Supervisor Agent Router
- MLflow performance tracking with custom SQL accuracy metrics
- Supports Vertex AI, Anthropic, OpenAI and local deployments
- Evaluated across 13 LLMs; RAG Router Pareto-optimal at 56 times lower cost

## pages

- https://tiaanvanantwerpen.com/: profile, how he thinks, experience, projects, writing, education
- https://tiaanvanantwerpen.com/projects/omni-apps: project, Omni Apps
- https://tiaanvanantwerpen.com/projects/wedding-planning-pa: project, A wedding-planning PA
- https://tiaanvanantwerpen.com/projects/llm-routing-nl2sql: project, LLM Routing for Text-to-SQL
- https://tiaanvanantwerpen.com/blog: writing
- https://tiaanvanantwerpen.com/blog/the-factory-moved-into-the-inbox: post, The factory moved into the inbox
- https://tiaanvanantwerpen.com/blog/model-is-not-the-hard-part: post, The model is not the hard part
- https://tiaanvanantwerpen.com/blog/adaptive-llm-routing: post, Adaptive LLM routing for effective agentic workflows
- https://tiaanvanantwerpen.com/adventures: field notes, hiking and the outdoors

Every page has a markdown version at the same path plus `/index.md` (the home page's is https://tiaanvanantwerpen.com/index.md). The whole site is in one file at https://tiaanvanantwerpen.com/llms-full.txt, and https://tiaanvanantwerpen.com/llms.txt is the index.

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