Breaktime Tech Talks

Ep66: Neo4j Data Loading at Scale + Vector Search Filtering


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Hear about my hard-won lessons from loading a large-scale book dataset into Neo4j with Ollama embeddings, plus a preview of exciting new vector search features.

Highlights:

Data Loading Battle Stories

  • Fixing Ollama OpenAI endpoint issues (drop the /v1 suffix!)
  • Choosing embedding models with adequate context windows (nomic-embed-text: 8,192 tokens)
  • Optimizing batch sizes and memory configuration
  • Using EXPLAIN to identify and eliminate Cypher eager operations
  • Error handling with ON ERROR CONTINUE for partial loads (achieved 83% coverage)
  • Neo4j 2026.01 Preview: Vector Search with Filters Three new approaches that combine vector search with Cypher filtering in a single query:

    • Vector Search + Keyword Filters
    • Cypher After Vector (post-filtering GraphRAG)
    • Cypher Before Vector (pre-filtering on subgraphs)
    • No more two-step application logic for Graph RAG!

      Context Graph demo app:
      • Level of detail and perspectives you can view of the context graph and interactions with agents
      • Event

        I will be at Jfokus in Stockholm next week!

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        Breaktime Tech TalksBy jmhreif

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