380 lines
13 KiB
Python
380 lines
13 KiB
Python
"""
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Qdrant 混合检索器模块
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提供基于 Qdrant 的混合检索（Dense + Sparse）功能，包括：
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- 纯混合检索（无子父文档）
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- 父子文档混合检索（先检索子文档，再返回父文档）
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核心原理：
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- 使用 Qdrant 原生 Fusion API (RRF) 做分数融合
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- 同时使用稠密向量（语义）和稀疏向量（BM25 关键词）
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"""
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from typing import Dict, Any, Optional, List
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from qdrant_client import QdrantClient
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from qdrant_client.http.exceptions import UnexpectedResponse
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from qdrant_client.http.models import (
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SearchRequest, Fusion, FusionProtocol, NamedVector, NamedSparseVector
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)
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from langchain_core.documents import Document
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from langchain_core.embeddings import Embeddings
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from langchain_core.retrievers import BaseRetriever, RetrieverOutput
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from rag_core import QdrantVectorStore, get_sparse_embedder, create_docstore
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from rag_core.client import create_qdrant_client as create_core_qdrant_client
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from app.model_services import get_embedding_service
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from app.logger import info, warning, debug
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# 模块级常量
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DEFAULT_SEARCH_K = 20
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DEFAULT_PARENT_SEARCH_K = 5
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class HybridRetriever(BaseRetriever):
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"""
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混合检索器：稠密向量 + BM25 稀疏向量 RRF 分数融合
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直接使用 Qdrant 原生 Fusion API，性能最优。
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"""
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def __init__(
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self,
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collection_name: str,
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vector_store: QdrantVectorStore,
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search_k: int = DEFAULT_SEARCH_K,
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):
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"""
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Args:
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collection_name: Qdrant 集合名称
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vector_store: QdrantVectorStore 实例
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search_k: 检索返回结果数
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"""
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self.collection_name = collection_name
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self.vector_store = vector_store
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self.search_k = search_k
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self.client = vector_store.get_qdrant_client()
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self.sparse_embedder = get_sparse_embedder()
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def _get_relevant_documents(
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self, query: str, *, run_manager: Optional[Any] = None
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) -> List[Document]:
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"""
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同步检索相关文档
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Args:
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query: 查询字符串
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run_manager: LangChain 运行管理器（可选）
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Returns:
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相关文档列表
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"""
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# 生成双向量
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dense_query = self.vector_store.embeddings.embed_query(query)
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sparse_query = self.sparse_embedder.embed_query(query)
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# 构建双检索请求
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searches = [
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# 稠密检索
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SearchRequest(
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vector=NamedVector(name="dense", vector=dense_query),
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limit=self.search_k,
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with_payload=True
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),
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# 稀疏检索
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SearchRequest(
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vector=NamedSparseVector(name="sparse", vector=sparse_query),
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limit=self.search_k,
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with_payload=True
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)
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]
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# RRF 分数融合
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fused_results = self.client.fusion(
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collection_name=self.collection_name,
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requests=searches,
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fusion=Fusion(fusion=FusionProtocol.RRF)
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)
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# 转换为 Document 格式
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results = []
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for point in fused_results.points:
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doc = Document(
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page_content=point.payload.pop("text", ""),
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metadata=point.payload
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)
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results.append(doc)
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debug(f"混合检索返回 {len(results)} 个文档")
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return results
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async def _aget_relevant_documents(
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self, query: str, *, run_manager: Optional[Any] = None
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) -> List[Document]:
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"""异步检索（当前调用同步版本）"""
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# Qdrant 客户端没有原生 async，这里用同步版本
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return self._get_relevant_documents(query, run_manager=run_manager)
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class ParentHybridRetriever(BaseRetriever):
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"""
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父子文档混合检索器：
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1. 先用混合检索找到相关子文档
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2. 根据子文档的 parent_id 找到对应的父文档
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3. 去重并返回父文档
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"""
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def __init__(
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self,
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collection_name: str,
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vector_store: QdrantVectorStore,
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search_k: int = DEFAULT_PARENT_SEARCH_K,
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docstore: Optional[Any] = None,
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):
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"""
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Args:
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collection_name: Qdrant 集合名称
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vector_store: QdrantVectorStore 实例
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search_k: 最终返回的父文档数
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docstore: 文档存储（如果父文档在 PostgreSQL），可选
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"""
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self.collection_name = collection_name
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self.vector_store = vector_store
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self.search_k = search_k
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self.client = vector_store.get_qdrant_client()
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self.sparse_embedder = get_sparse_embedder()
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self.docstore = docstore
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def _get_relevant_documents(
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self, query: str, *, run_manager: Optional[Any] = None
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) -> List[Document]:
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"""
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同步检索相关父文档
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Args:
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query: 查询字符串
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run_manager: LangChain 运行管理器（可选）
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Returns:
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相关父文档列表
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"""
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# 1. 生成查询双向量
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dense_query = self.vector_store.embeddings.embed_query(query)
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sparse_query = self.sparse_embedder.embed_query(query)
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# 2. 多取一些子文档，避免去重后数量不足
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search_limit = self.search_k * 2
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searches = [
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# 稠密检索
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SearchRequest(
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vector=NamedVector(name="dense", vector=dense_query),
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limit=search_limit,
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with_payload=True
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),
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# 稀疏检索
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SearchRequest(
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vector=NamedSparseVector(name="sparse", vector=sparse_query),
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limit=search_limit,
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with_payload=True
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)
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]
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# 3. RRF 分数融合，拿到子文档命中结果
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fused_results = self.client.fusion(
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collection_name=self.collection_name,
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requests=searches,
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fusion=Fusion(fusion=FusionProtocol.RRF)
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)
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if not fused_results.points:
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debug("混合检索未找到任何文档")
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return []
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# 4. 收集 parent_id 和对应最高得分
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parent_score_map = {}
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parent_ids = set()
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child_point_map = {} # 保存子文档点用于降级
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for point in fused_results.points:
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parent_id = point.payload.get("parent_id", point.id)
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score = point.score
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# 同一个 parent_id 只保留最高得分
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if parent_id not in parent_score_map or score > parent_score_map[parent_id]:
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parent_score_map[parent_id] = score
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parent_ids.add(parent_id)
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child_point_map[parent_id] = point
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# 5. 批量查询父文档
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# 首先尝试从 Qdrant 直接查询（因为父文档可能也存在 Qdrant 中）
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parent_docs = []
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found_parent_ids = set()
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try:
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parent_points = self.client.retrieve(
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collection_name=self.collection_name,
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ids=list(parent_ids),
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with_payload=True
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)
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# 处理找到的父文档
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for point in parent_points:
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doc = Document(
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page_content=point.payload.pop("text", ""),
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metadata=point.payload
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)
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parent_docs.append(doc)
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found_parent_ids.add(point.id)
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except Exception as e:
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warning(f"从 Qdrant 查询父文档失败: {e}")
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# 6. 如果有 docstore，尝试从 docstore 查询剩余的父文档
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if self.docstore and len(found_parent_ids) < len(parent_ids):
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missing_parent_ids = parent_ids - found_parent_ids
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try:
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docstore_docs = self.docstore.mget(missing_parent_ids)
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for doc_id, doc in zip(missing_parent_ids, docstore_docs):
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if doc is not None:
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parent_docs.append(doc)
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found_parent_ids.add(doc_id)
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except Exception as e:
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warning(f"从 docstore 查询父文档失败: {e}")
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# 7. 降级：对于仍未找到的父文档，用子文档本身代替
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missing_parent_ids = parent_ids - found_parent_ids
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if missing_parent_ids:
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warning(f"以下 parent_id 未找到对应的父文档，将返回子文档本身: {missing_parent_ids}")
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for parent_id in missing_parent_ids:
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child_point = child_point_map.get(parent_id)
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if child_point:
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doc = Document(
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page_content=child_point.payload.pop("text", ""),
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metadata=child_point.payload
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)
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parent_docs.append(doc)
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# 8. 按照得分降序排序，返回前 k 个
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parent_docs_with_scores = [
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(doc, parent_score_map.get(doc.metadata.get("id", doc.id), 0.0))
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for doc in parent_docs
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]
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parent_docs_with_scores.sort(key=lambda x: x[1], reverse=True)
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final_docs = [doc for doc, _ in parent_docs_with_scores[:self.search_k]]
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debug(f"父子文档混合检索返回 {len(final_docs)} 个父文档")
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return final_docs
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async def _aget_relevant_documents(
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self, query: str, *, run_manager: Optional[Any] = None
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) -> List[Document]:
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"""异步检索（当前调用同步版本）"""
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return self._get_relevant_documents(query, run_manager=run_manager)
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def create_hybrid_retriever(
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collection_name: str,
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search_k: int = DEFAULT_SEARCH_K,
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embeddings: Optional[Embeddings] = None,
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) -> BaseRetriever:
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"""
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创建混合检索器（稠密向量 + BM25 稀疏向量）。
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这是默认推荐的检索方式，效果最优。
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Args:
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collection_name: Qdrant 集合名称
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search_k: 检索返回结果数
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embeddings: 可选的嵌入模型实例。若未提供，将自动获取统一嵌入服务。
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Returns:
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HybridRetriever 实例
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"""
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# 默认使用统一嵌入服务
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if embeddings is None:
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embeddings = get_embedding_service()
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info("✅ 使用统一嵌入服务（本地 llama.cpp → 智谱 API 自动降级）")
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# 创建向量存储
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vector_store = QdrantVectorStore(collection_name=collection_name, embeddings=embeddings)
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# 验证集合是否存在
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try:
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vector_store.get_client().get_collection(collection_name)
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except UnexpectedResponse as e:
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if e.status_code == 404:
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warning(f"⚠️ Qdrant 集合 '{collection_name}' 不存在，请先创建并索引文档")
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raise ValueError(f"Qdrant 集合 '{collection_name}' 不存在")
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raise
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info(f"✅ Qdrant 混合检索器初始化成功（search_k={search_k}）")
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return HybridRetriever(
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collection_name=collection_name,
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vector_store=vector_store,
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search_k=search_k
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)
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def create_parent_hybrid_retriever(
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collection_name: str,
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search_k: int = DEFAULT_PARENT_SEARCH_K,
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embeddings: Optional[Embeddings] = None,
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use_docstore: bool = True,
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) -> BaseRetriever:
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"""
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创建父子文档混合检索器（默认推荐）。
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检索流程：
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1. 混合检索找到相关子文档
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2. 根据 parent_id 找到对应的父文档
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3. 去重并返回父文档
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Args:
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collection_name: Qdrant 集合名称
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search_k: 最终返回的父文档数
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embeddings: 可选的嵌入模型实例
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use_docstore: 是否使用 PostgreSQL docstore 存储父文档
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Returns:
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ParentHybridRetriever 实例
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"""
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# 默认使用统一嵌入服务
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if embeddings is None:
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embeddings = get_embedding_service()
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info("✅ 使用统一嵌入服务（本地 llama.cpp → 智谱 API 自动降级）")
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# 创建向量存储
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vector_store = QdrantVectorStore(collection_name=collection_name, embeddings=embeddings)
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# 验证集合是否存在
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try:
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vector_store.get_client().get_collection(collection_name)
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except UnexpectedResponse as e:
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if e.status_code == 404:
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warning(f"⚠️ Qdrant 集合 '{collection_name}' 不存在，请先创建并索引文档")
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raise ValueError(f"Qdrant 集合 '{collection_name}' 不存在")
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raise
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# 创建 docstore（如果需要）
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docstore = None
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if use_docstore:
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try:
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docstore, _ = create_docstore()
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info("✅ 文档存储初始化成功（PostgreSQL）")
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except Exception as e:
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warning(f"⚠️ 文档存储初始化失败，将不使用 docstore: {e}")
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info(f"✅ Qdrant 父子文档混合检索器初始化成功（search_k={search_k}）")
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return ParentHybridRetriever(
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collection_name=collection_name,
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vector_store=vector_store,
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search_k=search_k,
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docstore=docstore
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)
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# 别名：默认就是父子文档混合检索
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create_retriever = create_parent_hybrid_retriever
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