Model Selection for Evaluating Azure OpenAI GPT-4o NL-to-SQL Performance

Question

Hello Community,

We are developing a solution in Azure AI Studio where we use Azure OpenAI's GPT-4o model to convert natural language queries into SQL statements. This involves an agent workflow using the SQL Database toolkit, where the model generates the SQL, executes it, and formats the final answer.

We are implementing an evaluation pipeline using the LLM-as-a-Judge methodology (likely with a tool like DeepEval) to assess the accuracy, relevance, and correctness of the entire process.

We are currently considering two main options for the evaluation model (the "judge" model):

Use the same model (GPT-4o) as the judge.

Use a different, potentially more powerful/specialized model.

Our primary goal is to minimize bias and ensure the most objective and accurate evaluation of the NL-to-SQL conversion logic and final results, specifically within the Azure ecosystem.

The following questions are for the community:

Within the Azure AI environment, which specific model is considered the best practice for acting as an objective "judge" when evaluating GPT-4o's performance on complex text-to-SQL tasks?

Are models like Claude 3 Opus (if available in Azure) or Gemini 1.5 Pro superior choices for this specific reasoning task compared to GPT-4o itself?

If GPT-4o must be used as both the generator and judge due to infrastructure constraints, what are the best prompt engineering techniques to mitigate self-enhancement bias in the evaluation?

Are there specific Azure AI evaluation tools or features (e.g., in Azure AI Foundry) that facilitate this kind of objective model comparison for agent workflows?

Detailed G-Eval metrics are planned to be used to verify SQL logic correctness, execution validity, and final answer accuracy. Guidance from those with experience in NL-to-SQL evaluation in Azure would be appreciated

Answer 1

In the Azure AI environment, when evaluating the performance of the GPT-4o model for NL-to-SQL tasks, it is important to consider the following points regarding model selection and evaluation:

1. Best Practice for Objective "Judge" Model: While using the same model (GPT-4o) as both the generator and judge can simplify the evaluation process, it may introduce bias. If infrastructure allows, using a different model that is specialized in reasoning tasks could provide a more objective evaluation. However, specific recommendations for alternative models like Claude 3 Opus or Gemini 1.5 Pro are not provided in the current context, so their suitability would need to be assessed based on their performance in similar tasks.
2. Mitigating Self-Enhancement Bias: If GPT-4o must be used as both the generator and judge, employing effective prompt engineering techniques is crucial. This could involve structuring prompts in a way that encourages critical evaluation of the generated SQL queries, perhaps by asking the model to identify potential flaws or limitations in its own outputs.
3. Azure AI Evaluation Tools: The Azure AI Foundry provides various evaluation tools and features that can facilitate objective model comparisons. Utilizing built-in evaluation methods and metrics, such as those for assessing accuracy and relevance, can help ensure a thorough evaluation of the agent workflows.
4. G-Eval Metrics: Implementing detailed G-Eval metrics to verify SQL logic correctness, execution validity, and final answer accuracy is a sound approach. This will provide a structured way to assess the performance of the NL-to-SQL conversion logic.

Overall, the choice of the evaluation model and the methods used to mitigate bias are critical in ensuring the accuracy and relevance of the evaluation results in the Azure ecosystem.

Answer 2

Hello Kavita Dashwant,

Welcome to Microsoft Q&A and Thank you for reaching out.

I understand that You’re working on a sophisticated NL-to-SQL setup with GPT-4o and evaluating that workflow objectively is an important part of ensuring accuracy and reliability. Below is a clear, structured explanation that brings together the best practices from Azure and your additional points.

Choosing the Best Judge Model in Azure AI

Within the Azure AI ecosystem, the most effective judge models for NL-to-SQL evaluation are GPT-4o-mini or GPT-4.1. These models are optimized for reasoning, evaluation, and structured scoring, and they provide more deterministic behavior than GPT-4o. Using a different model than your SQL generator also helps reduce self-enhancement bias in your evaluations.

Considering Other Models Like Claude or Gemini

Models such as Claude 3 Opus or Gemini 1.5 Pro may offer strong reasoning capabilities. However, they are not yet available natively in Azure. Using them through external endpoints can introduce data governance, residency, and compliance issues. If they become available inside Azure later, you can revisit model benchmarks and documentation to assess suitability.

Prompt Engineering To Reduce Bias (If Using GPT-4o as Both Generator and Judge)

If you must rely on GPT-4o for both SQL generation and evaluation, you can still manage bias with the right strategies. Using role-based prompts helps define the evaluator as an independent reviewer. Adding diverse phrasing and contextual variety also prevents repeated reasoning patterns that may skew results. Enforcing JSON-only output ensures structured scoring, and blind-review prompts prevent the model from assuming it generated the SQL.

Using Strict G-Eval Style Rubrics

Structured evaluation frameworks like G-Eval can improve objectivity. You can require the model to score SQL queries on accuracy, schema correctness, and faithfulness to the natural language question. These rubrics help keep evaluations consistent even when using the same model for both tasks.

Azure AI Tools for Objective Evaluation

Azure provides excellent tools to support this workflow. Azure AI Evaluation Studio allows side-by-side comparisons and supports both LLM-based and human scoring. Model Benchmarks (Preview) can test the same prompt across multiple judge models. Agent Trace & Evaluation helps you evaluate each step in an NL-to-SQL agent pipeline. DeepEval can also integrate with Azure to validate SQL correctness and maintain structured evaluation results.

If you want the most objective, Azure-native evaluation, GPT-4o-mini or GPT-4.1 are the recommended judge models. If external models become available inside Azure later, they may be worth testing. If you must use GPT-4o to judge itself, use bias-reduction techniques like blind reviewing, structured rubrics, and JSON scoring.

Please refer this

• Azure OpenAI Service Models
• How to Use Model Router for Azure AI Foundry
• Understanding GPT-4o Model Characteristics

I Hope this helps. Do let me know if you have any further queries.

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