zhuyongxin
f035538531
Replace legacy MilvusServiceClient knowledge search/write with a single MilvusClientV2 hybrid store (BM25 function + dense ANN + RRFRanker). Use collection biz_hybrid and require knowledge reindex.
35 lines
1.4 KiB
Markdown
35 lines
1.4 KiB
Markdown
# Change: Real BM25 hybrid search and drop legacy SDK path
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## Why
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Delivery 2 shipped application-layer multi-path + sparse-lite lexical ranking. Product requirement is **true dense + BM25 hybrid retrieval**. Legacy `MilvusServiceClient` search path will be abandoned in this change; keep a single knowledge vector backend based on Milvus Java SDK v2 (`MilvusClientV2`) with BM25 function + `hybridSearch` + RRF.
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## What Changes
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- New hybrid collection schema: dense float vector + analyzed text + sparse BM25 output
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- Write path inserts text for BM25 auto-sparsification and dense embedding
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- Search path: single backend
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- dense mode: dense ANN only
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- hybrid mode: dense ANN + BM25 sparse ANN fused by RRFRanker
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- Remove/disable legacy SDK `search` / `searchSimilarDocumentsWithSdk` knowledge path and mode routing (`sdk|spring|auto`)
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- KnowledgeSearchPort adapter calls the single backend
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- Config: collection name, search mode, rrf-k, path weights optional
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- Tests for store mapping/fusion wiring; no dependency on live Zilliz in unit tests
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## Non-goals
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- Automatic full production reindex job UI
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- Cross-encoder model rerank
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- Keeping dual Spring-AI + SDK knowledge search modes
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## Impact
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- **Breaking for existing `biz` collection**: requires new hybrid collection + reindex
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- Agent tool contract unchanged
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- Interface: L2 internal retrieval backend
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## Depends on
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- Delivery 1 chunk identity
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- Delivery 2 SearchPort (will replace sparse-lite hybrid implementation)
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