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Poor Vector Search Results — Troubleshooting Guide

A practical workflow for diagnosing weak semantic retrieval in AI applications.

Troubleshooting

Start with the symptom. End with a verified fix.

What’s wrong?

Relevant documents exist but vector search repeatedly returns weak or irrelevant results.

Possible causes

  1. Poor chunking
  2. weak query representation
  3. embedding mismatch
  4. insufficient metadata filtering
  5. ranking problem
  6. stale index

Diagnosis

  1. Inspect top-k results
  2. compare queries and chunks
  3. test metadata filters
  4. verify embeddings and index freshness
  5. measure retrieval relevance

2 · Fix

Correct the confirmed retrieval weakness and validate it against representative queries.

Verify

Compare top-k relevance and downstream answer quality before and after the change.

3 · Prevent

Maintain retrieval evaluation data and monitor relevance regressions.

Poor Vector Search Results

Inspect the retrieval result itself before blaming generation.

Diagnose

Review top-k results for representative queries. Check chunk boundaries, metadata filters, embedding configuration, index freshness, and whether reranking is needed.

Fix → Verify → Prevent

Change one retrieval variable at a time, compare relevance against a fixed test set, and keep the winning configuration versioned.

Engineering companion

Learn → troubleshoot → design → prepare → test

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