What is Multi-Stage Retrieval Pipeline
Multi-Stage Retrieval Pipeline - A composable chain of filter, sort, reduce, enrich, and apply stages that progressively refine search results over unstructured data.
A multi-stage retrieval pipeline is the query language for unstructured data. Like SQL composes WHERE, ORDER BY, LIMIT, and JOIN for structured data, multi-stage retrieval composes filter, sort, reduce, enrich, and apply stages for multimodal content. Each stage takes the previous stage's output as input, progressively narrowing and enriching the result set.
How It Works
A pipeline is defined as an ordered list of stages. The first stage (usually a filter) searches across an embedding space to produce an initial candidate set. Subsequent stages narrow, reorder, sample, or enrich those candidates. For example: face search (847 candidates) → logo filter (23) → sentiment sort (23 reordered) → top-k reduce (5) → brand context enrich (5 enriched results).
The SQL Analogy
- Filter stages are like WHERE clauses: they narrow the candidate set by embedding similarity or metadata
- Sort stages are like ORDER BY: they re-rank results by weighted combinations of scores
- Reduce stages are like LIMIT and DISTINCT: they control output size via sampling or deduplication
- Enrich stages are like JOIN: they attach data from other collections (the semantic join)
- Apply stages are like INSERT INTO...SELECT: they write results or trigger side effects
Best Practices
- Start with broad filter stages and narrow progressively; don't over-constrain early
- Use sort stages to combine multiple ranking signals with explicit weights
- Always include a reduce stage to control output size
- Use enrich stages for cross-collection context instead of client-side merging
- Test pipelines with different stage orders, since the sequence affects both quality and latency
Related Pages
- Retriever documentation: /docs/retrieval/retrievers
- Retrieval Cookbook: /docs/retrieval/cookbook
- Blog: Multi-Stage Retrieval Pipelines - /blog/multi-stage-retrieval-pipelines