Vector search finds candidates. Reranking decides what your RAG app reads
You ask a retrieval-augmented generation (RAG) application a question. Vector search returns ten passages that are clearly related to the topic. The passage that actually contains the answer, however, is ranked seventh, while the language model receives only the first five. Retrieval did not completely fail. It found the evidence, but ordered it below less useful context. Reranking addresses that gap between a passage that is semantically similar and a passage that is relevant to the user's specific question. This article demonstrates that pattern in four Azure services using the Stanford Question Answering Dataset (SQuAD). The goal is not to declare a winning service or publish a quality benchmark. It is to show where retrieval, rank fusion, and model-based reranking run in each architecture, and to illustrate how the position of a known source passage can change. What this demonstration establishes The examples show rank movement for three selected questions. They do not establish that one reranker or service is universally more accurate. A production decision requires a larger, representative query set and aggregate relevance, latency, and cost measurements. Get the full Python implementation: pauldj54/azure-vector-reranking-squad Retrieval and reranking are different stages A production search pipeline commonly uses two stages: Retrieve for recall. Fast retrieval narrows a large corpus to a bounded candidate set. It can use vector search, keyword search, or both. Rerank for precision. A more expensive model evaluates only those candidates against the original query and produces the final order. Reciprocal Rank Fusion (RRF) belongs between those two ideas. RRF is a model-free rank aggregation method that merges independent result lists, usually vector and keyword results. For a document d, a typical score is: RRF(d) = ∑ r ∈ R 1 k + rank r (d) Here, R is the set of ranked lists and k is commonly 60. RRF works with positions rather than raw scores, so it can combine signals such as cosine distance and BM25 without pretending their score scales are comparable. This gives a clearer three-part vocabulary: Stage Purpose Typical mechanism Retrieve Find broad candidate set Vector search, BM25, filters Fuse Combine independent rankings RRF Rerank Reassess query-document relevance Semantic ranker or cross-encoder RRF often improves hybrid retrieval when exact names, dates, identifiers, or terms matter. A learned reranker can then read the query and each candidate together, capturing interactions that separately generated embeddings can miss. The learned stage costs more, so it should operate on tens of candidates rather than the whole corpus. The following image describes the general process: Why use SQuAD for this demonstration? SQuAD 1.1 contains crowd-written questions over more than 500 Wikipedia articles. Its packaged splits contain 87,599 training rows and 10,570 validation rows. Each row includes a question, a context passage, and one or more answer spans inside that passage. That source-context mapping gives this demonstration a useful label: the context associated with a question is treated as its gold passage. We can then inspect whether each search stage moves that passage up or down. This is convenient, but it is not a perfect passage-ranking benchmark. SQuAD was designed for extractive question answering, and another passage in the corpus might also answer a question. The gold context is therefore a reproducible reference, not proof that every other passage is irrelevant. The results shown here use the 2,067 unique contexts in the SQuAD validation split and 1,536-dimensional embeddings. The repository default should be set to the same corpus size before treating the screenshots or rank transitions as directly reproducible. Three illustrative questions Question Expected answer Gold context According to game stats, which Super Bowl 50 quarterback had his worst year since his first NFL season? Peyton Manning 12, Super Bowl 50 What else did Tesla do for work at this time? Various electrical repair jobs 165, Nikola Tesla Who acts as laborer, paymaster, and design team for a renovation project? The property owner 1306, Construction Each notebook selects a seeded demonstration question when it runs. The three saved examples were collected across separate runs; the current notebooks do not execute all three questions in one pass. A benchmark harness should iterate over a fixed question list and save all stage results in one structured output. Capability boundaries at a glance Service Retrieval and Fusion Learned Reranking Boundary to Keep in Mind Azure AI Search Native keyword and vector retrieval with native RRF Built-in semantic ranker Semantic ranking only reorders the retrieved top 50 Azure SQL Database Exact vector retrieval in the current notebook External Cohere model invoked through native REST procedure SQL issues the HTTPS request; Foundry performs inference PostgreSQL Flexible Server pgvector plus hand-written SQL RRF over full-text search Optional external Cohere call from Python Retrieval primitives are native; this RRF query and Cohere path are application code Azure Cosmos DB for NoSQL Native vector search and native hybrid RRF SDK-integrated Semantic Reranker, currently preview Reranking is a separate inference call over at most 50 supplied documents Azure AI Search: native hybrid retrieval and semantic ranking How it works: Azure AI Search provides the most integrated pipeline in this demonstration. A hybrid query runs keyword and vector retrieval, combines the lists with RRF, and passes up to the top 50 results to the built-in semantic ranker. The semantic ranker assigns @search.rerankerScore values from 0 to 4 and can return extractive captions and answers. The semantic configuration identifies the fields that carry the meaning of each document: semantic_search = SemanticSearch( configurations=[ SemanticConfiguration( name=SEMANTIC_CONFIG, prioritized_fields=SemanticPrioritizedFields( title_field=SemanticField(field_name="title"), content_fields=[SemanticField(field_name="content")], ), ) ] ) This tells the semantic ranker which text fields to evaluate. The query then enables semantic ranking after hybrid retrieval: results = search_client.search( search_text=question, vector_queries=[vector_query], query_type="semantic", semantic_configuration_name=SEMANTIC_CONFIG, top=10, ) The important constraint is candidate recall. Semantic ranking does not search the corpus again. If the correct passage is absent from the hybrid top 50, the semantic stage cannot recover it. See 01_azure_ai_search_reranking.ipynb for the complete setup and query path. Test results for Azure AI Search These examples show that semantic reranking improves relevance selectively, not universally. It strongly helps the construction query, moving the correct passage from rank 4 to rank 1, but slightly degrades the Super Bowl and Tesla queries by one position. This reinforces that semantic ranking should be evaluated across a representative query set using aggregate metrics such as MRR or NDCG, rather than judged from a single result. Azure SQL Database: vector retrieval plus external Cohere reranking How it works. The Azure SQL notebook retrieves 20 candidates with exact cosine distance and sends their text to Cohere Rerank v4.0 Fast through sys.sp_invoke_external_rest_endpoint. The vector column and query vector must have the same dimensions. This repository uses 1,536-dimensional embeddings: SELECT TOP (@ candidate_count) context_id, title, content, 1 - VECTOR_DISTANCE( 'cosine', CAST(@ query_vector AS VECTOR(1536)), embedding ) AS similarity FROM dbo.documents ORDER BY similarity DESC; For reranking, we selected Cohere Rerank v4.0 Fast (Cohere-rerank-v4.0-fast), a fast version of Cohere’s fourth-generation relevance-ranking model. The model is deployed in Microsoft Foundry, where its Azure Direct inference endpoint is available in the deployment details within the Foundry portal. Azure SQL can call REST APIs directly using sp_invoke_external_rest_endpoint. Because Azure SQL allowlists Azure AI’s *.cognitiveservices.azure.com domain, we translate the equivalent Foundry endpoint from *.services.ai.azure.com while preserving the Cohere reranking route. from urllib.parse import urlsplit, urlunsplit def sql_compatible_endpoint(endpoint: str) -> str: """Convert an Azure Direct endpoint to Azure SQL's allowed hostname.""" parts = urlsplit(endpoint) if parts.hostname.endswith(".services.ai.azure.com"): resource = parts.hostname.removesuffix(".services.ai.azure.com") hostname = f"{resource}.cognitiveservices.azure.com" elif parts.hostname.endswith(".cognitiveservices.azure.com"): hostname = parts.hostname else: raise ValueError("Expected an Azure AI Services endpoint.") return urlunsplit( (parts.scheme, hostname, parts.path, parts.query, "") ) Then I defined a re-rank with cohere function, starting by loading the endpoint and setting the authentication: def rerank_with_cohere( cursor, question: str, candidates: list[dict], top_n: int = 10, ) -> list[dict]: """ Rerank candidate documents by calling Cohere through Azure SQL. Each candidate must contain a 'content' field. """ if not candidates: return [] sql_endpoint = sql_compatible_endpoint( os.environ["COHERE_RERANK_ENDPOINT"] ) model = os.environ["COHERE_RERANK_MODEL"] access_token = credential.get_token( "https://cognitiveservices.azure.com/.default" ).token headers = json.dumps({"Authorization": f"Bearer {access_token}"}) payload = json.dumps( { "model": model, "query": question, "documents": [row["content"] for row in candidates], "top_n": min(k, len(candidates)), }, ensure_ascii=False, ) cursor.execute( """ DECLARE @url NVARCHAR(4000) = CAST(? AS NVARCHAR(4000)); DECLARE @headers NVARCHAR(4000) = CAST(? AS NVARCHAR(4000)); DECLARE Payload NVARCHAR(MAX) = CAST(? AS NVARCHAR(MAX)); DECLARE Response NVARCHAR(MAX); DECLARE @status INT; EXEC @status = sys.sp_invoke_external_rest_endpoint @url = @url, @method = 'POST', @headers = @headers, Payload = Payload, @timeout = 60, @retry_count = 2, Response = Response OUTPUT; SELECT @status, Response; """, sql_endpoint, headers, payload, ) status, response_text = cursor.fetchone() if status != 0: raise RuntimeError(f"Reranker endpoint returned HTTP status {status}.") response = json.loads(response_text)["result"] You can see the complete implementation in the 02_azure_sql_reranking.ipynb notebook. Test results for Azure SQL Db Across the three sample questions, Cohere reranking consistently moved the correct SQuAD passage closer to the top: from rank 5 to 1 for the Super Bowl question, 3 to 2 for the Tesla question, and 8 to 1 for the construction question. These examples show how vector search provides a strong candidate set, while reranking applies deeper query-document relevance scoring to improve the final ordering. The results are illustrative rather than a complete quality benchmark, so broader evaluation across many queries is still recommended. Azure Database for PostgreSQL flexible server: pgvector, SQL RRF, and an optional model How it works: PostgreSQL makes the pipeline components explicit. The notebook uses pgvector for vector similarity, PostgreSQL full-text search for keyword retrieval, and SQL to implement RRF. Vector retrieval uses cosine distance: SELECT context_id, title, content, 1 - (embedding <= > % (query_vector) s:: vector) AS similarity FROM squad_docs ORDER BY embedding <= > % (query_vector) s:: vector LIMIT % (candidate_count) s; The hybrid query independently ranks vector and keyword hits, then combines positions rather than raw scores: SELECT d.context_id, COALESCE(1.0 / (60 + v.rank), 0) + COALESCE(1.0 / (60 + k.rank), 0) AS rrf_score FROM squad_docs AS d LEFT JOIN vector_hits AS v USING (context_id) LEFT JOIN keyword_hits AS k USING (context_id) WHERE v.context_id IS NOT NULL OR k.context_id IS NOT NULL ORDER BY rrf_score DESC; This is not a built-in PostgreSQL RRF operator. It is transparent, hand-written SQL over native retrieval primitives, which makes weighting and debugging flexible but leaves implementation and tuning with the application team. The notebook's optional learned stage sends the vector candidates from Python to a Foundry deployment of Cohere Rerank v4.0 Fast. This path was chosen because the tested Flexible Server azure_ai extension version expected the older serverless reranking endpoint contract. Microsoft documentation still describes azure_ai.rank() as a preview function whose default model is Cohere Rerank v3.5, even though that model retired on May 14, 2026. Treat this as a version-specific compatibility issue and verify current extension behavior before selecting an architecture. Azure HorizonDB is a different product path. Its AI Model Management feature can provision Cohere Rerank v4.0 Fast as default-reranker, but that management feature is currently a limited preview. It should not be described as a generally available Flexible Server capability. See 03_azure_postgres_reranking.ipynb for the full SQL and optional external model path. Test results for Azure SQL for PostgreSQL Flexible Server The tests show that PostgreSQL vector search provides a useful candidate set, SQL RRF can substantially improve results when keyword evidence is strong, and the Cohere semantic reranker is the most consistent overall: it moved the correct passage to rank 1 in two tests and from rank 3 to rank 2 in the Tesla test. RRF produced the biggest gain for the construction question, moving the correct passage from outside the vector top five to rank 1, but did not improve every query. The scores across stages are not directly comparable because cosine similarity, RRF score, and Cohere relevance use different scales. Azure Cosmos DB for NoSQL: hybrid search with built-in RRF How it works: Azure Cosmos DB for NoSQL supports native hybrid ranking with VectorDistance, FullTextScore, and RRF inside ORDER BY RANK: SELECT TOP K C.context_id, c.title, c.text FROM c ORDER BY RANK RRF( VectorDistance(c.vector, @query_vector), FullTextScore(c.text, @term1, @term2, @term3) ) The notebook extracts distinct terms from the question before building the full-text part of the query. That token selection is application logic and can materially affect the hybrid ranking, so production evaluation should test analyzers, languages, term extraction, and optional RRF weights. Cosmos DB Semantic Reranker is an SDK-integrated preview feature. The application first runs a query, serializes the resulting documents, and submits those documents with the user's context string: result = container.semantic_rerank( context=question, documents=documents, options={ "return_documents": False, "top_k": min(k, len(documents)), "sort": True, "document_type": "json", "target_paths": "title,text", }, ) The service accepts at most 50 documents per rerank call and returns relevance scores from 0 to 1, plus inference latency and token usage. It uses the Microsoft semantic ranking model also used by Azure AI Search. The reranking call requires Microsoft Entra authentication, the appropriate Semantic Reranker role, and an account-linked inference endpoint. The 04_azure_cosmosdb_reranking.ipynb in the shared repo contains and end-to-end implementation. Test results for Azure Cosmos Db The results show that vector search provides a strong baseline, while hybrid RRF and semantic reranking improve different queries in different ways. Hybrid RRF helps when exact keywords matter, moving the construction answer into the top results, while the semantic reranker delivers the strongest overall ordering, promoting the correct construction passage from hybrid rank 3 to rank 1 and improving the Super Bowl answer from rank 5 to rank 2. However, it does not always place the gold passage first, as seen in the Tesla example, confirming that reranking improves relevance but is query-dependent and should be evaluated across a larger test set. What the examples do and do not show The four services expose different ownership boundaries: • Azure AI Search owns hybrid fusion and learned semantic ranking inside the search service. • Azure SQL owns vector retrieval and outbound REST invocation in this example, while Foundry owns model inference. • PostgreSQL supplies vector and full-text primitives; the application owns the RRF SQL and optional Cohere call. • Cosmos DB provides native hybrid RRF and integrates a separate preview inference call through its SDK. Across three selected questions, the known source passage often moved substantially. That supports the practical value of testing a second-stage ranker. It does not prove that semantic reranking always improves top-1 accuracy, that RRF is universally beneficial, or that scores from different stages can be compared directly. Cosine similarity, RRF score, Azure AI Search reranker score, Cohere relevance, and Cosmos DB semantic relevance all have different definitions and scales. Compare rank positions and task-level metrics, not raw values across systems. Turn the demonstration into an evaluation For a production RAG system, convert the notebook pattern into a repeatable evaluation harness: Build a representative labeled query set from real user tasks. Freeze corpus, chunking, embedding model, dimensions, and candidate counts for each run. Record ranks after retrieval, fusion, and learned reranking. Measure Recall@k or Hit@k to verify that retrieval finds relevant evidence. Measure Mean Reciprocal Rank (MRR) when the position of the first relevant result matters. Use NDCG when judgments include multiple passages or graded relevance. Record latency percentiles, inference usage, request cost, and failure rates. Evaluate the generated answer separately for correctness, citation support, and refusal behavior. Also test the operational cases that a three-question demonstration cannot cover: empty keyword results, missing gold passages, long documents, multilingual text, filters, partial outages, token expiration, throttling, model retirement, and low-confidence scores. Practical guidance Retrieve broadly enough that the correct evidence can reach the learned stage. Use RRF when vector and keyword retrieval provide complementary signals. Rerank a bounded candidate set, commonly 20 to 50 passages, and measure the latency cost. Keep citations and source identifiers through every rank transformation. Version the corpus, embedding model, dimensions, query set, and reranker deployment. Do not hard-code assumptions about model endpoints or lifecycle dates. Verify current service documentation and the deployed extension or SDK version. Add thresholds or fallback behavior only after calibrating scores on your own data. Judge the full RAG chain. Better passage order is valuable only when it improves grounded answers for users. Vector search is built to find plausible candidates quickly. Rank fusion can reconcile retrieval signals, and a learned reranker can decide which candidates best address the question. The right architecture depends on where your data lives, which service boundaries you want to operate, and what your evaluation says about quality, latency, and cost. Resources Companion repository Azure AI Search semantic ranker Azure SQL VECTOR_DISTANCE Azure SQL sp_invoke_external_rest_endpoint Azure Database for PostgreSQL AI functions Microsoft Foundry model retirement schedule Azure Cosmos DB hybrid search Azure Cosmos DB Semantic Reranker SQuAD dataset card Dataset attribution Rajpurkar, P., Zhang, J., Lopyrev, K., and Liang, P. (2016). SQuAD: 100,000+ Questions for Machine Comprehension of Text. EMNLP 2016. SQuAD 1.1 is distributed under CC BY-SA 4.0.Agents League: The Esports-Inspired Hackathon Where AI Agents Battle for Glory
Ready to put your AI skills to the ultimate test? Agents League is here, a dynamic, esports-inspired developer challenge that brings the thrill of live competition to the world of agentic AI. Whether you're a seasoned AI developer or just getting started, this is your chance to build, compete, and win. What is Agents League? Agents League is a week-long hackathon running as part of AI Skills Fest (June 4–14, 2026). Unlike traditional hackathons, Agents League combines live AI coding battles, asynchronous project submissions, and a thriving Discord community all competing for a total prize pool of $55,000 USD. This isn't just about building it's about showcasing what's possible with agentic AI in a format that's fast, competitive, and globally accessible. Three Challenge Tracks Pick One or Compete in All 1. Creative Apps Build innovative applications using GitHub Copilot for AI-assisted development. Show off your creativity and demonstrate how AI can accelerate app creation from concept to code. 2. Reasoning Agents Create intelligent agents using Microsoft Foundry that solve complex problems through multi-step reasoning. This track is all about building agents that can think, plan, and execute. 3. Enterprise Agents Build business-ready knowledge agents integrated with Microsoft 365 Copilot, authored in Copilot Studio. Perfect for developers focused on real-world enterprise solutions. Live Microsoft Reactor Events—Don't Miss the Battles! The heart of Agents League beats through live Microsoft Reactor events. Watch experts go head-to-head in live coding battles, learn cutting-edge techniques, and get inspired for your own submissions: Event What You'll Learn Creative Apps Battle See GitHub Copilot in action as experts build innovative apps live Reasoning Agents Battle Watch multi-step reasoning agents come to life with Microsoft Foundry Enterprise Agents Battle Learn to build M365-integrated agents with Copilot Studio 👉 View the full event series Key Dates Registration Deadline: June 12, 2026, 12:00 PM PT Hacking Period: June 4–14, 2026 Submission Deadline: June 14, 2026, 11:59 PM PT What You Get Live coding battles with expert demonstrations Curated technical experiences and on-demand content Learning resources on Microsoft Learn and AI Skills Navigator Community support through Discord GitHub-based submissions for transparent, collaborative judging Why Participate? Agents League isn't just another hackathon. It's designed as a streamlined, competitive format that: ✅ Fits into your schedule with focused, time-boxed challenges ✅ Provides real-world product innovation experience ✅ Offers global accessibility—participate from anywhere ✅ Demonstrates the latest capabilities of agentic AI, including new IQ tools ✅ Connects you with a passionate developer community Ready to Enter the Arena? Register Now for Agents League Before you register: Review the Hackathon Rules and Regulations for prize categories and judging criteria Join the Microsoft Reactor event series for live battles and learning Check out the Microsoft Event Code of Conduct Join the Conversation Have questions? Want to connect with fellow competitors? Join the Agents League community on Discord and start strategizing with developers from around the world. Whether you're building creative apps, reasoning agents, or enterprise solutions—the arena awaits. May the best agent win! 🏆 Agents League hackathon is open to the public and offered at no cost. Government employees should check with their employers to ensure participation is permitted in accordance with applicable policies. Related Links: Agents League Hackathon Registration Microsoft Reactor Series AI Skills FestJoin our free livestream series on using Microsoft IQ with Python
Join us for a new 3-part livestream series where we take a deep technical look at Microsoft IQ, the knowledge layer for the next generation of AI experiences. You'll learn how Foundry IQ, Work IQ, and Fabric IQ can be used to ground AI systems in organizational knowledge, workplace context, and structured business data. Our series will cover: Foundry IQ for multi-source agentic retrieval on search indexes, SharePoint, websites, and more Work IQ for user-specific retrieval of M365 data, like Teams chats, emails, and calendar events Fabric IQ for retrieval of data stored in OneLake, via Fabric ontologies and data agents Building agents with Microsoft Agent Framework to connect to Foundry IQ, Fabric IQ, and Work IQ Throughout the series, we’ll use Python for all examples and share full code so you can run everything yourself in your own Foundry projects. 👉 Register for the full series. In addition to the live streams, you can also join the Microsoft Foundry Discord to ask follow-up questions after each stream. If you are new to generative AI with Python, start with our 9-part Python + AI series, which covers topics such as LLMs, embeddings, RAG, tool calling, MCP, and agents. If you are new to Microsoft Agent Framework, watch our 6-part Python + Agent series which dives deep into agents and workflows. To learn more about each live stream or register for individual sessions, scroll down: Day 1: Foundry IQ 28 July, 2026 | 5:00 PM - 6:00 PM (UTC) Coordinated Universal Time Register for the stream on Reactor In the first session of our Microsoft IQ Deep Dive with Python series, we’ll kick things off with an introduction to the Microsoft IQ family: Foundry IQ, Work IQ, Fabric IQ, and Web IQ. We’ll then take a deeper look at Foundry IQ (Azure AI Search), exploring how it helps agents and applications work with curated knowledge and organizational context. We'll build a knowledge base and connect it to multiple knowledge sources, including the new IQs, MCP servers, and search indexes built from ingested data. Then we'll perform multi-source agentic retrieval on the knowledge base, which executes queries in parallel and merges the results with state-of-the-art ranking models. Finally, we will build an agent in Python using Microsoft Agent Framework and ground the agent's responses in results from the Foundry IQ knowledge base. All code demos will use Python and will be available in an open-source repository for you to deploy yourself. After the stream, join office hours in the Microsoft Foundry Discord to ask follow-up questions. Day 2: Work IQ 29 July, 2026 | 5:00 PM - 6:00 PM (UTC) Coordinated Universal Time Register for the stream on Reactor In the second session of our Microsoft IQ Deep Dive with Python series, we’ll focus on Work IQ and how it brings workplace context into AI-powered experiences. We’ll explore how developers can use Work IQ through APIs, A2A patterns, MCP integration, and tool-based workflows. We’ll look at two practical tool examples, then show how Work IQ can be used from Copilot and from a Microsoft Agent Framework agent. All code demos will use Python and will be available in an open-source repository for you to deploy yourself. After the stream, join office hours in the Microsoft Foundry Discord to ask follow-up questions. Day 3: Fabric IQ 30 July, 2026 | 5:00 PM - 6:00 PM (UTC) Coordinated Universal Time Register for the stream on Reactor In the final session of our Microsoft IQ Deep Dive with Python series, we’ll explore Fabric IQ and how it connects AI experiences to structured business data. We’ll introduce the key concepts behind Fabric IQ, including ontologies and data agents, and show how they help describe, organize, and reason over operational data stored in OneLake. We’ll use the Microsoft Fabric API SDK in Python to connect to Fabric IQ, so that we can programmatically configure ontologies and answer questions about our data. All code demos will use Python and will be available in an open-source repository for you to deploy yourself. After the stream, join office hours in the Microsoft Foundry Discord to ask follow-up questions.Mastering Query Fields in Azure AI Document Intelligence with C#
Introduction Azure AI Document Intelligence simplifies document data extraction, with features like query fields enabling targeted data retrieval. However, using these features with the C# SDK can be tricky. This guide highlights a real-world issue, provides a corrected implementation, and shares best practices for efficient usage. Use case scenario During the cause of Azure AI Document Intelligence software engineering code tasks or review, many developers encountered an error while trying to extract fields like "FullName," "CompanyName," and "JobTitle" using `AnalyzeDocumentAsync`: The error might be similar to Inner Error: The parameter urlSource or base64Source is required. This is a challenge referred to as parameter errors and SDK changes. Most problematic code are looks like below in C#: BinaryData data = BinaryData.FromBytes(Content); var queryFields = new List<string> { "FullName", "CompanyName", "JobTitle" }; var operation = await client.AnalyzeDocumentAsync( WaitUntil.Completed, modelId, data, "1-2", queryFields: queryFields, features: new List<DocumentAnalysisFeature> { DocumentAnalysisFeature.QueryFields } ); One of the reasons this failed was that the developer was using `Azure.AI.DocumentIntelligence v1.0.0`, where `base64Source` and `urlSource` must be handled internally. Because the older examples using `AnalyzeDocumentContent` no longer apply and leading to errors. Practical Solution Using AnalyzeDocumentOptions. Alternative Method using manual JSON Payload. Using AnalyzeDocumentOptions The correct method involves using AnalyzeDocumentOptions, which streamlines the request construction using the below steps: Prepare the document content: BinaryData data = BinaryData.FromBytes(Content); Create AnalyzeDocumentOptions: var analyzeOptions = new AnalyzeDocumentOptions(modelId, data) { Pages = "1-2", Features = { DocumentAnalysisFeature.QueryFields }, QueryFields = { "FullName", "CompanyName", "JobTitle" } }; - `modelId`: Your trained model’s ID. - `Pages`: Specify pages to analyze (e.g., "1-2"). - `Features`: Enable `QueryFields`. - `QueryFields`: Define which fields to extract. Run the analysis: Operation<AnalyzeResult> operation = await client.AnalyzeDocumentAsync( WaitUntil.Completed, analyzeOptions ); AnalyzeResult result = operation.Value; The reason this works: The SDK manages `base64Source` automatically. This approach matches the latest SDK standards. It results in cleaner, more maintainable code. Alternative method using manual JSON payload For advanced use cases where more control over the request is needed, you can manually create the JSON payload. For an example: var queriesPayload = new { queryFields = new[] { new { key = "FullName" }, new { key = "CompanyName" }, new { key = "JobTitle" } } }; string jsonPayload = JsonSerializer.Serialize(queriesPayload); BinaryData requestData = BinaryData.FromString(jsonPayload); var operation = await client.AnalyzeDocumentAsync( WaitUntil.Completed, modelId, requestData, "1-2", features: new List<DocumentAnalysisFeature> { DocumentAnalysisFeature.QueryFields } ); When to use the above: Custom request formats Non-standard data source integration Key points to remember Breaking changes exist between preview versions and v1.0.0 by checking the SDK version. Prefer `AnalyzeDocumentOptions` for simpler, error-free integration by using built-In classes. Ensure your content is wrapped in `BinaryData` or use a direct URL for correct document input: Conclusion Using AnalyzeDocumentOptions provides a cleaner and more reliable way to work with query fields in Azure AI Document Intelligence using C#. By aligning with the latest SDK approach, developers can simplify implementation, reduce common errors, and improve code maintainability. Keeping up with SDK enhancements and recommended practices ensures more accurate and efficient document data extraction. As Azure AI capabilities continue to evolve, adopting modern integration patterns will help you build scalable and future-ready document processing solutions with greater confidence. Reference Official AnalyzeDocumentAsync Documentation. Official Azure SDK documentation. Azure Document Intelligence C# SDK support add-on query field.
Building an End-to-End Azure RAG Strategy Agent with MS Foundry
High-Level Architecture This architecture represents an end-to-end Retrieval-Augmented Generation (RAG) pipeline where raw documents are ingested from Azure Blob Storage, processed using Document Intelligence, transformed into embeddings via Azure OpenAI, and indexed in Azure AI Search for hybrid retrieval. A Foundry/MAF-based agent orchestrates query processing by combining user input with relevant search results and generates contextual responses, which are exposed through a FastAPI or CLI interface. This solution is composed of two main layers: 1. Data Ingestion Layer (RAG Pipeline) This layer transforms raw enterprise documents into searchable knowledge. Flow: Raw documents stored in Azure Blob Storage Supported formats: PDF, DOCX, PPTX, images, etc. Document Intelligence extraction Extracts: Text Tables Key-value pairs Structure Writes output as structured JSON back to Blob (processed/) Chunking + Embedding Documents are split into chunks Each chunk is embedded using Azure OpenAI (text-embedding-*) Indexing into Azure AI Search Creates a hybrid index: Keyword search Semantic ranking Vector search Enables flexible retrieval strategies 2. Query Layer (Strategy Agents) This layer enables intelligent query answering. Flow: User sends a query via: FastAPI endpoint CLI interface Query is handled by: Microsoft Agent Framework (MAF) agent Running on Azure AI Foundry Agent: Queries Azure AI Search Retrieves top relevant chunks Injects them into LLM prompt LLM generates grounded response This follows the standard RAG pattern: Retrieval → Augmentation → Generation End-to-End Flow Key Azure Services Used Service Purpose Azure Blob Storage Raw + processed document storage Azure AI Document Intelligence Extract structured content Azure OpenAI Embeddings + LLM generation Azure AI Search Hybrid retrieval engine Azure AI Foundry Agent orchestration Microsoft Agent Framework Agent execution layer Why this Architecture Matters This solution goes beyond basic RAG and provides: Hybrid Retrieval Combines keyword + semantic + vector search Improves recall and accuracy Structured Document Parsing Handles complex enterprise documents Extracts tables and metadata Agent-Based Orchestration Enables reasoning over retrieval results Extensible for multi-agent workflows Scalable Data Pipeline Supports continuous ingestion Works with large document collections Enterprise Considerations Use Managed Identity for secure service access Apply RBAC on Cosmos DB / Search / Storage Enable Private Endpoints for network isolation Use Guardrails + Evaluations in Foundry Summary This repository demonstrates a production-ready Azure RAG architecture: Ingest → Extract → Chunk → Embed → Index Retrieve → Reason → Generate Powered by Azure AI Foundry + Agent Framework By combining data engineering + AI orchestration, it enables enterprise AI systems that are: Accurate Grounded Extensible Repo: https://github.com/snd94/azure-rag-strategy-agent Please refer to the Microsoft Learn Documentation for further information: Azure AI Search documentation - Azure AI Search | Microsoft Learn Document Intelligence documentation - Quickstarts, Tutorials, API Reference - Foundry Tools | Microsoft Learn How to generate embeddings with Azure OpenAI in Microsoft Foundry Models - Microsoft Foundry | Microsoft Learn How to generate embeddings with Azure OpenAI in Microsoft Foundry Models - Microsoft Foundry | Microsoft Learn Microsoft Agent Framework Overview | Microsoft Learn What is Microsoft Foundry? - Microsoft Foundry | Microsoft LearnWhen RAG Hits the Wall: Designing Systems That Scale from 1,000 to 1 million Documents
Introduction Retrieval-Augmented Generation (RAG) has quickly become the default architecture for grounding Large Language Models (LLMs) in enterprise data. And at small scale, it works exceptionally well. 100 documents → Excellent accuracy 1,000 documents → Still predictable With around 100 documents, RAG systems tend to produce highly accurate responses. Even at 1,000 documents, behavior remains predictable and reliable. However, as systems grow beyond tens of thousands - and especially into the range of hundreds of thousands or millions of documents - many implementations begin to degrade in surprising ways. Latency begins to rise nonlinearly. Retrieval precision declines, costs increase, and responses grow inconsistent. What looks like a model issue is usually an architectural one. The Hidden Theory Behind Early RAG Success Early RAG systems work well not because they are perfectly designed, but because small datasets are forgiving. In smaller corpora, irrelevant retrieval is naturally rare. Semantic similarity remains tightly clustered, and noise does not overwhelm signal. This creates an illusion of robustness - systems seem accurate even when the underlying retrieval strategy is weak. As scale increases, this illusion disappears. Breaking Point #1: Chunk Explosion (Entropy Growth) What Happens Most ingestion pipelines rely on token-based chunking: Document -> Fixed-size chunks -> Embed everything As document count increases, the system experiences entropy growth: The number of chunks grows faster than the number of documents, leading to a dense and noisy vector space. Similar information becomes fragmented, and retrieval precision drops. This is a manifestation of the curse of dimensionality - as the number of vectors increases, distance metrics lose meaning, and “nearest neighbors” stop being truly relevant. The Shift: Structural Information Retrieval To solve this production-grade RAG systems reintroduce structure. Instead of blindly splitting text, semantic chunking aligns content with logical boundaries like headings and sections. This preserves meaning and improves retrieval quality. Deduplication removes repeated templates and boilerplate, reducing unnecessary noise in the system. Hierarchical indexing allows retrieval to operate at multiple levels - document, section, and chunk - making search both more efficient and more accurate. These changes restore order in the vector space and significantly improve retrieval performance. Breaking Point #2: Vector Search Saturation What Happens As data grows, latency becomes one of the biggest bottlenecks. Many systems rely on runtime-heavy operations such as generating embeddings on demand or querying large, unpartitioned indexes. This leads to unbounded computation and poor scalability. Over time, retrieval cost trends toward linear complexity. Cache inefficiencies increase, and tail latency begins to dominate the user experience. The Shift: Systems Thinking Scaling RAG requires applying distributed systems principles. Partitioned indexes reduce the search space, allowing queries to operate on smaller, more relevant subsets of data. Precomputed embeddings shift expensive computation to ingestion time, eliminating runtime overhead. Caching strategies, informed by real-world usage patterns, significantly improve performance by reusing frequent query results. Together, these changes make latency predictable and systems more cost-efficient. The Final Trap: Context does not equal to Intelligence What Happens A common mistake in RAG systems is assuming that more context leads to better answers. In reality, LLMs are attention limited. As more tokens are added, attention becomes diluted, and the model struggles to focus on what matters. Excessive context introduces noise, reducing the overall quality of responses. The Shift: Information Compression Effective systems focus on quality over quantity. By limiting retrieval to the most relevant chunks, summarizing context, and grounding responses with citations, RAG systems achieve higher information density and better reasoning performance. What a Scalable RAG System Actually Represent At scale, RAG is no longer an LLM feature. It becomes a retrieval system with an LLM as a reasoning layer. Prototype RAG Production RAG Token chunking Structured IR Vector-only search Hybrid retrieval No ranking theory Reranking models Runtime-heavy Precomputed pipelines More context Information compression Final Insight Scaling RAG is not primarily a machine learning problem. It is a combination of information retrieval and distributed systems engineering, with the LLM acting as the final layer. Closing Thought If your RAG system works with 1,000 documents, you’ve validated an idea. If it works with 1 million documents, you’ve respected theory - and built an architecture. References RAG and Generative AI - Azure AI Search | Microsoft Learn Chunk and Vectorize by Document Layout - Azure AI Search | Microsoft Learn Chunk Documents - Azure AI Search | Microsoft Learn Hybrid Search Overview - Azure AI Search | Microsoft LearnIf You're Building AI on Azure, ECS 2026 is Where You Need to Be
Let me be direct: there's a lot of noise in the conference calendar. Generic cloud events. Vendor showcases dressed up as technical content. Sessions that look great on paper but leave you with nothing you can actually ship on Monday. ECS 2026 isn't that. As someone who will be on stage at Cologne this May, I can tell you the European Collaboration Summit combined with the European AI & Cloud Summit and European Biz Apps Summit is one of the few events I've seen where engineers leave with real, production-applicable knowledge. Three days. Three summits. 3,000+ attendees. One of the largest Microsoft-focused events in Europe, and it keeps getting better. If you're building AI systems on Azure, designing cloud-native architectures, or trying to figure out how to take your AI experiments to production — this is where the conversation is happening. What ECS 2026 Actually Is ECS 2026 runs May 5–7 at Confex in Cologne, Germany. It brings together three co-located summits under one roof: European Collaboration Summit — Microsoft 365, Teams, Copilot, and governance European AI & Cloud Summit — Azure architecture, AI agents, cloud security, responsible AI European BizApps Summit — Power Platform, Microsoft Fabric, Dynamics For Azure engineers and AI developers, the European AI & Cloud Summit is your primary destination. But don't ignore the overlap, some of the most interesting AI conversations happen at the intersection of collaboration tooling and cloud infrastructure. The scale matters here: 3,000+ attendees, 100+ sessions, multiple deep-dive tracks, and a speaker lineup that includes Microsoft executives, Regional Directors, and MVPs who have built, broken, and rebuilt production systems. The Azure + AI Track - What's Actually On the Agenda The AI & Cloud Summit agenda is built around real technical depth. Not "intro to AI" content, actual architecture decisions, patterns that work, and lessons from things that didn't. Here's what you can expect: AI Agents and Agentic Systems This is where the energy is right now, and ECS is leaning in. Expect sessions covering how to design agent workflows, chain reasoning steps, handle memory and state, and integrate with Azure AI services. Marco Casalaina, VP of Products for Azure AI at Microsoft, is speaking if you want to understand the direction of the Azure AI platform from the people building it, this is a direct line. Azure Architecture at Scale Cloud-native patterns, microservices, containers, and the architectural decisions that determine whether your system holds up under real load. These sessions go beyond theory you'll hear from engineers who've shipped these designs at enterprise scale. Observability, DevOps, and Production AI Getting AI to production is harder than the demos suggest. Sessions here cover monitoring AI systems, integrating LLMs into CI/CD pipelines, and building the operational practices that keep AI in production reliable and governable. Cloud Security and Compliance Security isn't optional when you're putting AI in front of users or connecting it to enterprise data. Tracks cover identity, access patterns, responsible AI governance, and how to design systems that satisfy compliance requirements without becoming unmaintainable. Pre-Conference Deep Dives One underrated part of ECS: the pre-conference workshops. These are extended, hands-on sessions typically 3–6 hours that let you go deep on a single topic with an expert. Think of them as intensive short courses where you can actually work through the material, not just watch slides. If you're newer to a particular area of Azure AI, or you want to build fluency in a specific pattern before the main conference sessions, these are worth the early travel. The Speaker Quality Is Different Here The ECS speaker roster includes Microsoft executives, Microsoft MVPs, and Regional Directors, people who have real accountability for the products and patterns they're presenting. You'll hear from over 20 Microsoft speakers: Marco Casalaina — VP of Products, Azure AI at Microsoft Adam Harmetz — VP of Product at Microsoft, Enterprise Agent And dozens of MVPs and Regional Directors who are in the field every day, solving the same problems you are. These aren't keynote-only speakers — they're in the session rooms, at the hallway track, available for real conversations. The Hallway Track Is Not a Cliché I know "networking" sounds like a corporate afterthought. At ECS it genuinely isn't. When you put 3,000 practitioners, engineers, architects, DevOps leads, security specialists in one venue for three days, the conversations between sessions are often more valuable than the sessions themselves. You get candid answers to "how are you actually handling X in production?" that you won't find in documentation. The European Microsoft community is tight-knit and collaborative. ECS is where that community concentrates. Why This Matters Right Now We're in a period where AI development is moving fast but the engineering discipline around it is still maturing. Most teams are figuring out: How to move from AI prototype to production system How to instrument and observe AI behaviour reliably How to design agent systems that don't become unmaintainable How to satisfy security and compliance requirements in AI-integrated architectures ECS 2026 is one of the few places where you can get direct answers to these questions from people who've solved them — not theoretically, but in production, on Azure, in the last 12 months. If you go, you'll come back with practical patterns you can apply immediately. That's the bar I hold events to. ECS consistently clears it. Register and Explore the Agenda Register for ECS 2026: ecs.events Explore the AI & Cloud Summit agenda: cloudsummit.eu/en/agenda Dates: May 5–7, 2026 | Location: Confex, Cologne, Germany Early registration is worth it the pre-conference workshops fill up. And if you're coming, find me, I'll be the one talking too much about AI agents and Azure deployments. See you in Cologne.
Building an Enterprise HR Chatbot with Multi-Strategy RAG and Live Agent Handoff on Azure
HR teams deal with thousands of employee questions every day — policy lookups, leave balances, case escalations, and sensitive topics like harassment or misconduct. AI chatbots can handle the routine stuff and free up HR advisors for the hard cases. But most chatbot projects get stuck at basic Q&A. They can't handle multi-country policies, employee slang, or smooth handoffs to a real person. This post covers how we built Eva, a production HR chatbot using Microsoft Bot Framework and Semantic Kernel on Azure. I'll focus on three problems and how we solved them: Getting accurate answers when employees and policy documents use different words Handing off to a live human advisor in real time Catching answer quality regressions automatically Why basic RAG isn't enough for HR Retrieval-Augmented Generation (RAG) — fetching relevant documents and feeding them to an LLM — is the standard approach. But plain RAG breaks down in HR for a few reasons: Vocabulary mismatch. An employee asks "How does misconduct affect my ACB?" but the policy document says "Annual Cash Bonus eligibility criteria." The search doesn't connect the two. Multi-country ambiguity. The same question can have different answers depending on the employee's country, grade, or role. Sensitive topics. Questions about harassment, disability, or whistleblowing should go to a human, not get an AI-generated answer. Ranking noise. Search results often include globally relevant but locally irrelevant documents. Eva handles these with a layered pipeline: query augmentation → multi-index search → LLM reranking → answer generation → citation handling. Architecture at a glance Layer Technology Bot framework Microsoft Agents SDK (aiohttp) LLM orchestration Semantic Kernel Primary LLM Azure OpenAI Service (GPT-4.1 / GPT-4o) Knowledge search Azure AI Search (hybrid + vector) Live agent chat Salesforce MIAW via server-sent events Evaluation Azure AI Evaluation SDK + custom LLM judge Config Pydantic-settings + Azure App Configuration + Key Vault Four retrieval strategies, controlled by feature flags Instead of one search approach, Eva supports four — toggled by feature flags so we can A/B test per country without code changes. They run in a priority cascade: HyDE (Hypothetical Document Embeddings) Instead of searching with the employee's question, the LLM first generates a hypothetical policy document thatwouldanswer it. We embed that synthetic document and use it as the search query. Since a hypothetical answer is closer in embedding space to the real answer than the original question is, this bridges vocabulary gaps effectively. Step-back prompting The LLM broadens the question. "How does misconduct affect my ACB?" becomes "What is the Annual Cash Bonus policy and what factors affect eligibility?" This works well when answers live in broader policy sections. Query rewrite The LLM expands abbreviations and adds HR domain context, then runs a hybrid (text + vector) search. Standard search (fallback) Basic intent classification with hybrid search. No augmentation. All four strategies return the same Pydantic model, so the rest of the pipeline doesn't care which one ran. The team can enable HyDE globally, roll out step-back to specific countries, or revert instantly if something underperforms. LLM reranking After pulling results from both a country-specific index and a global index, Eva optionally reranks them using a RankGPT-style approach — the LLM scores document relevance with a bias toward local content. If reranking fails for any reason, it falls back to the original ordering so the pipeline keeps moving. Answer generation with local vs. global context The answer stage separates retrieved documents into local context (country-specific) and global context (company-wide), injected as distinct prompt sections. The LLM returns a structured response with reasoning, the actual answer, citations, and a coverage classification (full, partial, or denial). Prompts are stored as version-controlled .txt files with per-model variants (e.g., gpt-4o.txt, gpt-4.1.txt), resolved at runtime. This makes prompts reviewable in PRs and deployable without code changes. Live agent handoff with Salesforce When Eva determines a question needs a human — sensitive topic, complex case, or the employee simply asks — it hands off to a Salesforce advisor in real time. SSE streaming. Eva keeps a persistent HTTP connection to Salesforce for real-time messages, typing indicators, and session end signals. Session resilience. Session state persists across three layers — in-memory cache, Azure Cosmos DB, and Bot Framework turn state — to survive restarts and failovers. Message delivery workers. Each session has a dedicated async worker with exponential backoff retry. Overflow messages go to a failed messages list rather than being silently dropped. Queue position updates. While employees wait, Eva queries Salesforce for queue position and sends rate-limited updates. Context handoff. On session start, Eva sends the full conversation transcript so advisors don't ask employees to repeat themselves. Automated evaluation Eva includes an evaluation framework that runs as a separate process, testing against ground-truth Q&A pairs from CSV files. Factual questions are scored using Azure AI's SimilarityEvaluator on a 1–5 scale, with optional relevance and groundedness checks. Sensitive questions (harassment, disability, whistleblowing) use a custom LLM judge that checks whether the response acknowledges sensitivity and directs the employee to create a case or speak with an advisor. A deviation detector flags score drops between runs. SQLite stores results for trending, and Application Insights powers dashboards. Long evaluation runs support resume — the framework skips already-completed test cases on restart. Key takeaways Make retrieval strategies swappable. Feature flags let you A/B test without redeploying. Separate local and global knowledge explicitly. Don't rely on the LLM to figure out which country's policy applies. Invest in evaluation early. Ground-truth datasets with factual and behavioral scoring catch regressions that manual testing misses. Build resilience into live agent handoff. Multi-tier session recovery and retry logic prevent dropped conversations. Treat prompts as code. File-based, model-variant-aware prompts are easier to maintain than inline strings. Use Pydantic for structured LLM outputs. Typed models catch bad output at the validation boundary instead of letting it propagate. Get started Semantic Kernel documentation — LLM orchestration with plugins and structured outputs Azure OpenAI Service quickstart — Deploy GPT-4o or GPT-4.1 Azure AI Search vector search tutorial — Hybrid and vector search indices Microsoft Bot Framework SDK — Build bots for Teams and web Azure AI Evaluation SDK — Score for similarity, relevance, and groundednessBuild an Offline Hybrid RAG Stack with ONNX and Foundry Local
If you are building local AI applications, basic retrieval augmented generation is often only the starting point. This sample shows a more practical pattern: combine lexical retrieval, ONNX based semantic embeddings, and a Foundry Local chat model so the assistant stays grounded, remains offline, and degrades cleanly when the semantic path is unavailable. Why this sample is worth studying Many local RAG samples rely on a single retrieval strategy. That is usually enough for a proof of concept, but it breaks down quickly in production. Exact keywords, acronyms, and document codes behave differently from natural language questions and paraphrased requests. This repository keeps the original lexical retrieval path, adds local ONNX embeddings for semantic search, and fuses both signals in a hybrid ranking mode. The generation step runs through Foundry Local, so the entire assistant can remain on device. Lexical mode handles exact terms and structured vocabulary. Semantic mode handles paraphrases and more natural language phrasing. Hybrid mode combines both and is usually the best default. Lexical fallback protects the user experience if the embedding pipeline cannot start. Architectural overview The sample has two main flows: an offline ingestion pipeline and a local query pipeline. The architecture splits cleanly into offline ingestion at the top and runtime query handling at the bottom. Offline ingestion pipeline Read Markdown files from docs/ . Parse front matter and split each document into overlapping chunks. Generate dense embeddings when the ONNX model is available. Store chunks in SQLite with both sparse lexical features and optional dense vectors. Local query pipeline The browser posts a question to the Express API. ChatEngine resolves the requested retrieval mode. VectorStore retrieves lexical, semantic, or hybrid results. The prompt is assembled with the retrieved context and sent to a Foundry Local chat model. The answer is returned with source references and retrieval metadata. The sequence diagram shows the difference between lexical retrieval and hybrid retrieval. In hybrid mode, the query is embedded first, then lexical and semantic scores are fused before prompt assembly. Repository structure and core components The implementation is compact and readable. The main files to understand are listed below. src/config.js : retrieval defaults, paths, and model settings. src/embeddingEngine.js : local ONNX embedding generation through Transformers.js. src/vectorStore.js : SQLite storage plus lexical, semantic, and hybrid ranking. src/chatEngine.js : retrieval mode resolution, prompt assembly, and Foundry Local model execution. src/ingest.js : document ingestion and embedding generation during indexing. src/server.js : REST endpoints, streaming endpoints, upload support, and health reporting. Getting started To run the sample, you need Node.js 20 or newer, Foundry Local, and a local ONNX embedding model. The default model path is models/embeddings/bge-small-en-v1.5 . cd c:\Users\leestott\local-hybrid-retrival-onnx npm install huggingface-cli download BAAI/bge-small-en-v1.5 --local-dir models/embeddings/bge-small-en-v1.5 npm run ingest npm start Ingestion writes the local SQLite database to data/rag.db . If the embedding model is available, each chunk gets a dense vector as well as lexical features. If the embedding model is missing, ingestion still succeeds and the application remains usable in lexical mode. Best practice: local AI applications should treat model files, SQLite data, and native runtime compatibility as part of the deployable system, not as optional developer conveniences. Code walkthrough 1. Retrieval configuration The sample makes its retrieval behaviour explicit in configuration. That is useful for testing and for operator visibility. export const config = { model: "phi-3.5-mini", docsDir: path.join(ROOT, "docs"), dbPath: path.join(ROOT, "data", "rag.db"), chunkSize: 200, chunkOverlap: 25, topK: 3, retrievalMode: process.env.RETRIEVAL_MODE || "hybrid", retrievalModes: ["lexical", "semantic", "hybrid"], fallbackRetrievalMode: "lexical", retrievalWeights: { lexical: 0.45, semantic: 0.55, }, }; Those defaults tell you a lot about the intended operating profile. Chunks are small, the number of returned chunks is low, and the fallback path is explicit. 2. Local ONNX embeddings The embedding engine disables remote model loading and only uses local files. That matters for privacy, repeatability, and air gapped operation. env.allowLocalModels = true; env.allowRemoteModels = false; this.extractor = await pipeline("feature-extraction", resolvedPath, { local_files_only: true, }); const output = await this.extractor(text, { pooling: "mean", normalize: true, }); The mean pooling and normalisation step make the vectors suitable for cosine similarity based ranking. 3. Hybrid storage and ranking in SQLite Instead of adding a separate vector database, the sample stores lexical and semantic representations in the same SQLite table. That keeps the local footprint low and the implementation easy to debug. searchHybrid(query, queryEmbedding, topK = 5, weights = { lexical: 0.45, semantic: 0.55 }) { const lexicalResults = this.searchLexical(query, topK * 3); const semanticResults = this.searchSemantic(queryEmbedding, topK * 3); if (semanticResults.length === 0) { return lexicalResults.slice(0, topK).map((row) => ({ ...row, retrievalMode: "lexical", })); } const fused = [...combined.values()].map((row) => ({ ...row, score: (row.lexicalScore * lexicalWeight) + (row.semanticScore * semanticWeight), })); fused.sort((a, b) => b.score - a.score); return fused.slice(0, topK); } The important point is not just the weighted fusion. It is the fallback behaviour. If semantic retrieval cannot provide results, the user still gets lexical grounding instead of an empty context window. 4. Retrieval mode resolution in ChatEngine ChatEngine keeps the runtime behaviour predictable. It validates the requested mode and falls back to lexical search when semantic retrieval is unavailable. resolveRetrievalMode(requestedMode) { const desiredMode = config.retrievalModes.includes(requestedMode) ? requestedMode : config.retrievalMode; if ((desiredMode === "semantic" || desiredMode === "hybrid") && !this.semanticAvailable) { return config.fallbackRetrievalMode; } return desiredMode; } This is a sensible production design because local runtime failures are common. Missing model files or native dependency mismatches should reduce quality, not crash the entire assistant. 5. Foundry Local model management The sample uses FoundryLocalManager to discover, download, cache, and load the configured chat model. const manager = FoundryLocalManager.create({ appName: "gas-field-local-rag" }); const catalog = manager.catalog; this.model = await catalog.getModel(config.model); if (!this.model.isCached) { await this.model.download((progress) => { const pct = Math.round(progress * 100); this._emitStatus("download", `Downloading ${this.modelAlias}... ${pct}%`, progress); }); } await this.model.load(); this.chatClient = this.model.createChatClient(); this.chatClient.settings.temperature = 0.1; This gives the app a better local startup experience. The server can expose a status stream while the model initialises in the background. User experience and screenshots The client is intentionally simple, which makes it useful during evaluation. You can switch retrieval mode, test questions quickly, and inspect the retrieved sources. The landing page exposes retrieval mode directly in the UI. That makes it easy to compare lexical, semantic, and hybrid behaviour during testing. The sources panel shows grounding evidence and retrieval scores, which is useful when validating whether better answers are coming from better retrieval or just model phrasing. Best practices for ONNX RAG and Foundry Local Keep lexical fallback alive. Exact identifiers and runtime failures both make this necessary. Persist sparse and dense features together where possible. It simplifies debugging and operational reasoning. Use small chunks and conservative topK values for local context budgets. Expose health and status endpoints so users can see when the model is still loading or embeddings are unavailable. Test retrieval quality separately from generation quality. Pin and validate native runtime dependencies, especially ONNX Runtime, before tuning prompts. Practical warning: this repository already shows why runtime validation matters. A local app can ingest documents successfully and still fail at model initialisation if the native runtime stack is misaligned. How this compares with RAG and CAG The strongest value in this sample comes from where it sits between a basic local RAG baseline and a curated CAG design. Dimension Classic local RAG This hybrid ONNX RAG sample CAG Context assembly Retrieve chunks at query time, often lexically, then inject them into the prompt. Retrieve chunks at query time with lexical, semantic, or fused scoring, then inject the strongest results into the prompt. Use a prepared or cached context pack instead of fresh retrieval for every request. Main strength Easy to implement and easy to explain. Better recall for paraphrases without giving up exact match behaviour or offline execution. Predictable prompts and low query time overhead. Main weakness Misses synonyms and natural language reformulations. More moving parts, larger local asset footprint, and native runtime compatibility to manage. Coverage depends on curation quality and goes stale more easily. Failure behaviour Weak retrieval leads to weak grounding. Semantic failure can degrade to lexical retrieval if designed properly, which this sample does. Prepared context can be too narrow for new or unexpected questions. Best fit Simple local assistants and proof of concept systems. Offline copilots and technical assistants that need stronger recall across varied phrasing. Stable workflows with tightly bounded, curated knowledge. Samples Related samples: - Foundry Local RAG - https://github.com/leestott/local-rag - Foundry Local CAG - https://github.com/leestott/local-cag - Foundry Local hybrid-retrival-onnx https://github.com/leestott/local-hybrid-retrival-onnx Specific benefits of this hybrid approach over classic RAG It captures paraphrased questions that lexical search would often miss. It still preserves exact match performance for codes, terms, and product names. It gives operators a controlled degradation path when the semantic stack is unavailable. It stays local and inspectable without introducing a separate hosted vector service. Specific differences from CAG CAG shifts effort into context curation before the request. This sample retrieves evidence dynamically at runtime. CAG can be faster for fixed workflows, but it is usually less flexible when the document set changes. This hybrid RAG design is better suited to open ended knowledge search and growing document collections. What to validate before shipping Measure retrieval quality in each mode using exact term, acronym, and paraphrase queries. Check that sources shown in the UI reflect genuinely distinct evidence, not repeated chunks. Confirm the application remains usable when semantic retrieval is unavailable. Verify ONNX Runtime compatibility on the real target machines, not only on the development laptop. Test model download, cache, and startup behaviour with a clean environment. Final take For developers getting started with ONNX RAG and Foundry Local, this sample is a good technical reference because it demonstrates a realistic local architecture rather than a minimal demo. It shows how to build a grounded assistant that remains offline, supports multiple retrieval modes, and fails gracefully. Compared with classic local RAG, the hybrid design provides better recall and better resilience. Compared with CAG, it remains more flexible for changing document sets and less dependent on pre curated context packs. If you want a practical starting point for offline grounded AI on developer workstations or edge devices, this is the most balanced pattern in the repository set.Vectorless Reasoning-Based RAG: A New Approach to Retrieval-Augmented Generation
Introduction Retrieval-Augmented Generation (RAG) has become a widely adopted architecture for building AI applications that combine Large Language Models (LLMs) with external knowledge sources. Traditional RAG pipelines rely heavily on vector embeddings and similarity search to retrieve relevant documents. While this works well for many scenarios, it introduces challenges such as: Requires chunking documents into small segments Important context can be split across chunks Embedding generation and vector databases add infrastructure complexity A new paradigm called Vectorless Reasoning-Based RAG is emerging to address these challenges. One framework enabling this approach is PageIndex, an open-source document indexing system that organizes documents into a hierarchical tree structure and allows Large Language Models (LLMs) to perform reasoning-based retrieval over that structure. Vectorless Reasoning-Based RAG Instead of vectors, this approach uses structured document navigation. User Query ->Document Tree Structure ->LLM Reasoning ->Relevant Nodes Retrieved ->LLM Generates Answer This mimics how humans read documents: Look at the table of contents Identify relevant sections Read the relevant content Answer the question Core features No Vector Database: It relies on document structure and LLM reasoning for retrieval. It does not depend on vector similarity search. No Chunking: Documents are not split into artificial chunks. Instead, they are organized using their natural structure, such as pages and sections. Human-like Retrieval: The system mimics how human experts read documents. It navigates through sections and extracts information from relevant parts. Better Explainability and Traceability: Retrieval is based on reasoning. The results can be traced back to specific pages and sections. This makes the process easier to interpret. It avoids opaque and approximate vector search, often called “vibe retrieval.” When to Use Vectorless RAG Vectorless RAG works best when: Data is structured or semi-structured Documents have clear metadata Knowledge sources are well organized Queries require reasoning rather than semantic similarity Examples: enterprise knowledge bases internal documentation systems compliance and policy search healthcare documentation financial reporting Implementing Vectorless RAG with Azure AI Foundry Step 1 : Install Pageindex using pip command, from pageindex import PageIndexClient import pageindex.utils as utils # Get your PageIndex API key from https://dash.pageindex.ai/api-keys PAGEINDEX_API_KEY = "YOUR_PAGEINDEX_API_KEY" pi_client = PageIndexClient(api_key=PAGEINDEX_API_KEY) Step 2 : Set up your LLM Example using Azure OpenAI: from openai import AsyncAzureOpenAI client = AsyncAzureOpenAI( api_key=AZURE_OPENAI_API_KEY, azure_endpoint=AZURE_OPENAI_ENDPOINT, api_version=AZURE_OPENAI_API_VERSION ) async def call_llm(prompt, temperature=0): response = await client.chat.completions.create( model=AZURE_DEPLOYMENT_NAME, messages=[{"role": "user", "content": prompt}], temperature=temperature ) return response.choices[0].message.content.strip() Step 3: Page Tree Generation import os, requests pdf_url = "https://arxiv.org/pdf/2501.12948.pdf" //give the pdf url for tree generation, here given one for example pdf_path = os.path.join("../data", pdf_url.split('/')[-1]) os.makedirs(os.path.dirname(pdf_path), exist_ok=True) response = requests.get(pdf_url) with open(pdf_path, "wb") as f: f.write(response.content) print(f"Downloaded {pdf_url}") doc_id = pi_client.submit_document(pdf_path)["doc_id"] print('Document Submitted:', doc_id) Step 4 : Print the generated pageindex tree structure if pi_client.is_retrieval_ready(doc_id): tree = pi_client.get_tree(doc_id, node_summary=True)['result'] print('Simplified Tree Structure of the Document:') utils.print_tree(tree) else: print("Processing document, please try again later...") Step 5 : Use LLM for tree search and identify nodes that might contain relevant context import json query = "What are the conclusions in this document?" tree_without_text = utils.remove_fields(tree.copy(), fields=['text']) search_prompt = f""" You are given a question and a tree structure of a document. Each node contains a node id, node title, and a corresponding summary. Your task is to find all nodes that are likely to contain the answer to the question. Question: {query} Document tree structure: {json.dumps(tree_without_text, indent=2)} Please reply in the following JSON format: {{ "thinking": "<Your thinking process on which nodes are relevant to the question>", "node_list": ["node_id_1", "node_id_2", ..., "node_id_n"] }} Directly return the final JSON structure. Do not output anything else. """ tree_search_result = await call_llm(search_prompt) Step 6 : Print retrieved nodes and reasoning process node_map = utils.create_node_mapping(tree) tree_search_result_json = json.loads(tree_search_result) print('Reasoning Process:') utils.print_wrapped(tree_search_result_json['thinking']) print('\nRetrieved Nodes:') for node_id in tree_search_result_json["node_list"]: node = node_map[node_id] print(f"Node ID: {node['node_id']}\t Page: {node['page_index']}\t Title: {node['title']}") Step 7: Answer generation node_list = json.loads(tree_search_result)["node_list"] relevant_content = "\n\n".join(node_map[node_id]["text"] for node_id in node_list) print('Retrieved Context:\n') utils.print_wrapped(relevant_content[:1000] + '...') answer_prompt = f""" Answer the question based on the context: Question: {query} Context: {relevant_content} Provide a clear, concise answer based only on the context provided. """ print('Generated Answer:\n') answer = await call_llm(answer_prompt) utils.print_wrapped(answer) When to Use Each Approach Both vector-based RAG and vectorless RAG have their strengths. Choosing the right approach depends on the nature of the documents and the type of retrieval required. When to Use Vector Database–Based RAG Vector-based retrieval works best when dealing with large collections of unrelated or loosely structured documents. In such cases, semantic similarity is often sufficient to identify relevant information quickly. Use vector RAG when: Searching across many independent documents Semantic similarity is sufficient to locate relevant content Real-time retrieval is required over very large datasets Common use cases include: Customer support knowledge bases Conversational chatbots Product and content search systems When to Use Vectorless RAG Vectorless approaches such as PageIndex are better suited for long, structured documents where understanding the logical organization of the content is important. Use vectorless RAG when: Documents contain clear hierarchical structure Logical reasoning across sections is required High retrieval accuracy is critical Typical examples include: Financial filings and regulatory reports Legal documents and contracts Technical manuals and documentation Academic and research papers In these scenarios, navigating the document structure allows the system to identify the exact section that logically contains the answer, rather than relying only on semantic similarity. Conclusion Vector databases significantly advanced RAG architectures by enabling scalable semantic search across large datasets. However, they are not the optimal solution for every type of document. Vectorless approaches such as PageIndex introduce a different philosophy: instead of retrieving text that is merely semantically similar, they retrieve text that is logically relevant by reasoning over the structure of the document. As RAG architectures continue to evolve, the future will likely combine the strengths of both approaches. Hybrid systems that integrate vector search for broad retrieval and reasoning-based navigation for precision may offer the best balance of scalability and accuracy for enterprise AI applications.
