Implement Phase 18: Hybrid Search (BM25 + Vector)

- FastEmbedSparse(Qdrant/bm25) 기반 sparse 임베딩 추가 (fastembed 패키지)
- IngestionService: HYBRID_SEARCH_ENABLED 시 dense + sparse 동시 저장 (RetrievalMode.HYBRID)
  - _ensure_collection_schema(): sparse vector 미설정 컬렉션 자동 삭제·재생성
- RetrieverService: hybrid 스토어 + dense 폴백 구조, Qdrant 내장 RRF로 결과 통합
- container.py: sparse_embeddings Singleton 프로바이더, ingestion/retriever 양쪽 주입
- .env.example: HYBRID_SEARCH_ENABLED, SPARSE_MODEL_ID 항목 추가

활성화: .env에 HYBRID_SEARCH_ENABLED=true 설정 후 기존 문서 재수집 필요

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
This commit is contained in:
sal
2026-05-29 17:47:17 +09:00
parent 145b0cc96f
commit 86370f6c1e
7 changed files with 88 additions and 22 deletions
+4
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@@ -15,3 +15,7 @@ DB_PASSWORD=
LANGCHAIN_TRACING_V2=false
LANGCHAIN_API_KEY=
LANGCHAIN_PROJECT=youlbot
# Hybrid Search (Phase 18) — BM25 + Vector (활성화 후 기존 문서 재수집 필요)
HYBRID_SEARCH_ENABLED=false
SPARSE_MODEL_ID=Qdrant/bm25
+4
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@@ -41,6 +41,10 @@ class Config(BaseSettings):
reranker_enabled: bool = False
reranker_model_id: str = "cross-encoder/mmarco-mMiniLMv2-L12-H384-v1" # 한국어 지원 다국어 모델
reranker_fetch_k: int = 10 # rerank 전 벡터 검색 후보 수 (rag_top_k보다 커야 함)
# Hybrid Search (Phase 18) — BM25 + Vector
hybrid_search_enabled: bool = False
sparse_model_id: str = "Qdrant/bm25" # fastembed sparse 모델 (언어 무관 BM25)
rag_verbose: bool = False
rag_show_sources: bool = False
langgraph_verbose: bool = False
+13 -5
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@@ -14,6 +14,7 @@ from services.ui.cli_service import CliUiService
from services.events.event_bus import EventBus
from services.events.handlers import StreamTokenHandler, StreamEndHandler
from langchain_huggingface import HuggingFaceEmbeddings
from langchain_qdrant import FastEmbedSparse
from services.rag.ingestion_service import IngestionService
from services.rag.rerank_service import RerankService
from services.rag.retriever_service import RetrieverService
@@ -96,6 +97,16 @@ class Container(containers.DeclarativeContainer):
model_kwargs=providers.Callable(lambda c: {"device": c.embedding_device}, config),
)
reranker = providers.Callable(
lambda c: RerankService(c.reranker_model_id) if c.reranker_enabled else None,
config,
)
sparse_embeddings = providers.Singleton(
lambda c: FastEmbedSparse(model_name=c.sparse_model_id) if c.hybrid_search_enabled else None,
config,
)
ingestion_service = providers.Singleton(
IngestionService,
embeddings=embeddings,
@@ -105,11 +116,7 @@ class Container(containers.DeclarativeContainer):
lambda c: c.semantic_breakpoint_threshold_type, config
),
buffer_size=providers.Callable(lambda c: c.semantic_buffer_size, config),
)
reranker = providers.Callable(
lambda c: RerankService(c.reranker_model_id) if c.reranker_enabled else None,
config,
sparse_embeddings=sparse_embeddings,
)
retriever_service = providers.Singleton(
@@ -120,6 +127,7 @@ class Container(containers.DeclarativeContainer):
top_k=providers.Callable(lambda c: c.rag_top_k, config),
reranker=reranker,
rerank_fetch_k=providers.Callable(lambda c: c.reranker_fetch_k, config),
sparse_embeddings=sparse_embeddings,
)
# Phase 3 — LangGraph Agent
+15 -9
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@@ -184,15 +184,21 @@ turns = conversation_repository.load_turns_after(self._conv_id, None, limit=10)
---
## Phase 18 — Hybrid Search (BM25 + Vector) ★★☆
## Phase 18 — Hybrid Search (BM25 + Vector) ★★☆
**배경**: 한국어 질문에서 고유명사·전문용어가 포함된 경우 의미 검색(Dense)만으로는 recall이 떨어진다. BM25 키워드 검색과 결합(Hybrid)하면 보완이 가능하다.
**구현 방식**:
- Qdrant의 Sparse Vector 지원 활용 (`FastEmbedSparseEmbeddings` 또는 BM42)
- 인덱싱 시 dense + sparse 두 벡터 동시 저장
- 검색 시 `RRF(Reciprocal Rank Fusion)`로 결과 통합
- `IngestionService`, `RetrieverService` 양쪽 수정 필요
**구현 내용**:
- `FastEmbedSparse(model_name="Qdrant/bm25")` — 언어 무관 BM25 sparse 임베딩 (`fastembed` 패키지)
- `IngestionService`: `HYBRID_SEARCH_ENABLED=true` 시 dense + sparse 동시 저장 (`RetrievalMode.HYBRID`)
- `RetrieverService`: hybrid 스토어로 검색 → Qdrant 내장 RRF로 결과 통합; sparse vector 미설정 컬렉션은 dense로 자동 폴백
- `_ensure_collection_schema()`: hybrid 전환 시 스키마 불일치 컬렉션 자동 재생성 (기존 문서 재수집 필요)
- `.env` `HYBRID_SEARCH_ENABLED=true`로 활성화, 활성화 후 기존 문서 재수집 필요
| 설정 | 기본값 | 설명 |
|------|--------|------|
| `HYBRID_SEARCH_ENABLED` | `false` | `true`로 설정 시 활성화 |
| `SPARSE_MODEL_ID` | `Qdrant/bm25` | fastembed sparse 모델 (첫 실행 시 자동 다운로드) |
**난이도**: 중간 | **임팩트**: 높음 (키워드 포함 질문 recall 대폭 향상)
@@ -271,8 +277,8 @@ docker-compose.yml
```
단기 (1~2주) 중기 (1개월) 장기
──────────────────────── ────────────────────── ──────────────────
Phase 18 Hybrid Search → Phase 15 (모델선택) → Phase 16 (Docker)
Phase 19 Query Rewriting → Phase 20 (RAGAS 평가) → Phase 17 (멀티모달)
Phase 19 Query Rewriting → Phase 15 (모델선택) → Phase 16 (Docker)
→ Phase 20 (RAGAS 평가) → Phase 17 (멀티모달)
```
### 우선순위 매트릭스
@@ -295,7 +301,7 @@ Phase 19 Query Rewriting → Phase 20 (RAGAS 평가) → Phase 17 (멀티모
| Phase 13 Semantic Chunker | ✅ 완료 | — | — | — |
| Phase 14 음성 인터페이스 | ✅ 완료 | — | — | — |
| Phase 13-B Reranker | ✅ 완료 | — | — | — |
| Phase 18 Hybrid Search | 🔲 신규 | 중간 | 높음 | ⭐ 1순위 |
| Phase 18 Hybrid Search | ✅ 완료 | | | |
| Phase 19 Query Rewriting | 🔲 신규 | 하 | 중간 | 3순위 |
| Phase 15 모델 선택 | 🔲 미완 | 중간 | 중간 | 4순위 |
| Phase 20 RAGAS 평가 | 🔲 신규 | 중간 | 중간 | 5순위 |
+2
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@@ -12,6 +12,8 @@ langchain-qdrant>=0.2.0
sentence-transformers>=3.0.0
qdrant-client>=1.9.0
pdfplumber>=0.11.0
# Phase 18 — Hybrid Search (BM25 sparse vectors)
fastembed>=0.3.0
# Phase 3 — Agent orchestration
langgraph>=1.0.0
# Phase 4 — Web UI
+21 -2
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@@ -1,6 +1,6 @@
from langchain_community.document_loaders import PDFPlumberLoader, TextLoader
from langchain_experimental.text_splitter import SemanticChunker
from langchain_qdrant import QdrantVectorStore
from langchain_qdrant import QdrantVectorStore, RetrievalMode
from qdrant_client import QdrantClient
from qdrant_client.models import Filter, FieldCondition, MatchValue, FilterSelector
@@ -15,10 +15,12 @@ class IngestionService:
collection_name: str,
breakpoint_threshold_type: str = "percentile",
buffer_size: int = 1,
sparse_embeddings=None,
):
self._embeddings = embeddings
self._qdrant_url = qdrant_url
self._collection_name = collection_name
self._sparse_embeddings = sparse_embeddings
self._splitter = SemanticChunker(
embeddings=embeddings,
breakpoint_threshold_type=breakpoint_threshold_type,
@@ -26,6 +28,18 @@ class IngestionService:
)
self._client = QdrantClient(url=qdrant_url)
def _ensure_collection_schema(self) -> None:
"""Hybrid 모드 전환 시 컬렉션에 sparse vector 설정이 없으면 삭제해 재생성을 유도한다."""
if not self._sparse_embeddings:
return
try:
info = self._client.get_collection(self._collection_name)
if not info.config.params.sparse_vectors:
print(f"[Hybrid] '{self._collection_name}' 컬렉션에 sparse vector 설정이 없어 재생성합니다.")
self._client.delete_collection(self._collection_name)
except Exception:
pass # 컬렉션 미존재 시 무시
def _delete_by_source(self, source_path: str) -> None:
"""같은 파일 경로로 저장된 기존 청크를 모두 삭제한다."""
try:
@@ -46,6 +60,7 @@ class IngestionService:
pass # 컬렉션이 없을 때(최초 수집) 무시
def ingest(self, file_paths: list[str]) -> int:
self._ensure_collection_schema()
docs = []
for path in file_paths:
self._delete_by_source(path)
@@ -53,10 +68,14 @@ class IngestionService:
docs.extend(loader.load())
chunks = self._splitter.split_documents(docs)
QdrantVectorStore.from_documents(
kwargs = dict(
documents=chunks,
embedding=self._embeddings,
url=self._qdrant_url,
collection_name=self._collection_name,
)
if self._sparse_embeddings:
kwargs["sparse_embedding"] = self._sparse_embeddings
kwargs["retrieval_mode"] = RetrievalMode.HYBRID
QdrantVectorStore.from_documents(**kwargs)
return len(chunks)
+28 -5
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@@ -1,5 +1,5 @@
from langchain_core.documents import Document
from langchain_qdrant import QdrantVectorStore
from langchain_qdrant import QdrantVectorStore, RetrievalMode
from qdrant_client import QdrantClient
from qdrant_client.models import Filter, FieldCondition, MatchValue, FilterSelector
@@ -15,24 +15,47 @@ class RetrieverService:
top_k: int,
reranker=None,
rerank_fetch_k: int = 10,
sparse_embeddings=None,
):
self._client = QdrantClient(url=qdrant_url)
self._collection_name = collection_name
self._store = QdrantVectorStore(
self._top_k = top_k
self._reranker = reranker
self._rerank_fetch_k = rerank_fetch_k
self._sparse_embeddings = sparse_embeddings
# Dense-only store — hybrid 실패 시 폴백으로도 사용
self._dense_store = QdrantVectorStore(
client=self._client,
collection_name=collection_name,
embedding=embeddings,
)
self._top_k = top_k
self._reranker = reranker
self._rerank_fetch_k = rerank_fetch_k
if sparse_embeddings:
self._store = QdrantVectorStore(
client=self._client,
collection_name=collection_name,
embedding=embeddings,
sparse_embedding=sparse_embeddings,
retrieval_mode=RetrievalMode.HYBRID,
)
else:
self._store = self._dense_store
def as_retriever(self):
return self._store.as_retriever(search_kwargs={"k": self._top_k})
def search(self, query: str) -> list[Document]:
fetch_k = self._rerank_fetch_k if self._reranker else self._top_k
try:
docs = self._store.similarity_search(query, k=fetch_k)
except Exception as e:
if self._sparse_embeddings:
# 컬렉션에 sparse vector 없음 → dense 폴백 (재수집 필요)
print(f"[Hybrid] 검색 실패, dense 폴백 (문서 재수집 필요): {e}")
docs = self._dense_store.similarity_search(query, k=fetch_k)
else:
raise
if self._reranker:
docs = self._reranker.rerank(query, docs, top_k=self._top_k)
return docs