使用外部托管的交叉编码器模型按字段进行重排序
在本教程中，您将学习如何使用存放在Amazon SageMaker上的跨编码器模型来重新排序搜索结果并提高搜索的相关性。
要重排文档，您需要配置一个在查询时处理搜索结果的搜索管道。该管道会拦截搜索结果并将其传递给ml_inference搜索响应处理器，该处理器调用交叉编码器模型。模型生成用于重排匹配文档by_field的分数。
先决条件：在Amazon SageMaker上部署模型
运行以下代码在Amazon SageMaker上部署模型。在本示例中，您将使用托管在Amazon SageMaker上的Hugging Face交叉编码器模型ms-marco-MiniLM-L-6-v2。我们建议使用GPU以获得更好的性能：
import sagemaker
import boto3
from sagemaker.huggingface import HuggingFaceModel
sess = sagemaker.Session()
role = sagemaker.get_execution_role()
hub = {
'HF_MODEL_ID':'cross-encoder/ms-marco-MiniLM-L-6-v2',
'HF_TASK':'text-classification'
}
huggingface_model = HuggingFaceModel(
transformers_version='4.37.0',
pytorch_version='2.1.0',
py_version='py310',
env=hub,
role=role,
)
predictor = huggingface_model.deploy(
initial_instance_count=1, # number of instances
instance_type='ml.m5.xlarge' # ec2 instance type
)
部署模型后，您可以通过在AWS管理控制台中转到Amazon SageMaker控制台并选择左侧标签中的”推理 > 端点”来找到模型端点。记下所创建模型的URL；您将使用它来创建连接器。
使用重排运行搜索
要使用重排运行搜索，请按照以下步骤操作：
1、创建连接器。
2、注册模型。
3、将文档摄入索引。
4、创建搜索管道。
5、使用重排进行搜索。
步骤1：创建连接器
通过在actions.url参数中提供模型URL来创建到交叉编码器模型的连接器：
POST /_plugins/_ml/connectors/_create
{
"name": "SageMaker cross-encoder model",
"description": "Test connector for SageMaker cross-encoder hosted model",
"version": 1,
"protocol": "aws_sigv4",
"credential": {
"access_key": "<YOUR_ACCESS_KEY>",
"secret_key": "<YOUR_SECRET_KEY>",
"session_token": "<YOUR_SESSION_TOKEN>"
},
"parameters": {
"region": "<REGION>",
"service_name": "sagemaker"
},
"actions": [
{
"action_type": "predict",
"method": "POST",
"url": "<YOUR_SAGEMAKER_ENDPOINT_URL>",
"headers": {
"content-type": "application/json"
},
"request_body": "{ \"inputs\": { \"text\": \"${parameters.text}\", \"text_pair\": \"${parameters.text_pair}\" }}"
}
]
}
记下响应中包含的连接器ID；您将在下一步中使用它。
步骤2：注册模型
要注册模型，请在connector_id参数中提供连接器ID：
POST /_plugins/_ml/models/_register
{
"name": "Cross encoder model",
"version": "1.0.1",
"function_name": "remote",
"description": "Using a SageMaker endpoint to apply a cross encoder model",
"connector_id": "<YOUR_CONNECTOR_ID>"
}
步骤3：将文档导入索引
创建索引并导入包含纽约市各行政区相关信息的示例文档：
POST /nyc_areas/_bulk
{ "index": { "_id": 1 } }
{ "borough": "Queens", "area_name": "Astoria", "description": "Astoria is a neighborhood in the western part of Queens, New York City, known for its diverse community and vibrant cultural scene.", "population": 93000, "facts": "Astoria is home to many artists and has a large Greek-American community. The area also boasts some of the best Mediterranean food in NYC." }
{ "index": { "_id": 2 } }
{ "borough": "Queens", "area_name": "Flushing", "description": "Flushing is a neighborhood in the northern part of Queens, famous for its Asian-American population and bustling business district.", "population": 227000, "facts": "Flushing is one of the most ethnically diverse neighborhoods in NYC, with a large Chinese and Korean population. It is also home to the USTA Billie Jean King National Tennis Center." }
{ "index": { "_id": 3 } }
{ "borough": "Brooklyn", "area_name": "Williamsburg", "description": "Williamsburg is a trendy neighborhood in Brooklyn known for its hipster culture, vibrant art scene, and excellent restaurants.", "population": 150000, "facts": "Williamsburg is a hotspot for young professionals and artists. The neighborhood has seen rapid gentrification over the past two decades." }
{ "index": { "_id": 4 } }
{ "borough": "Manhattan", "area_name": "Harlem", "description": "Harlem is a historic neighborhood in Upper Manhattan, known for its significant African-American cultural heritage.", "population": 116000, "facts": "Harlem was the birthplace of the Harlem Renaissance, a cultural movement that celebrated Black culture through art, music, and literature." }
{ "index": { "_id": 5 } }
{ "borough": "The Bronx", "area_name": "Riverdale", "description": "Riverdale is a suburban-like neighborhood in the Bronx, known for its leafy streets and affluent residential areas.", "population": 48000, "facts": "Riverdale is one of the most affluent areas in the Bronx, with beautiful parks, historic homes, and excellent schools." }
{ "index": { "_id": 6 } }
{ "borough": "Staten Island", "area_name": "St. George", "description": "St. George is the main commercial and cultural center of Staten Island, offering stunning views of Lower Manhattan.", "population": 15000, "facts": "St. George is home to the Staten Island Ferry terminal and is a gateway to Staten Island, offering stunning views of the Statue of Liberty and Ellis Island." }
步骤4：创建搜索管道
接下来，为重排创建搜索管道。在搜索管道配置中，input_map和output_map定义了如何为交叉编码器模型准备输入数据以及如何解释模型的输出以进行重排：
input_map指定搜索文档和查询中的哪些字段应作为模型输入：text字段映射到索引文档中的facts字段。它提供了模型将分析的文档特定内容。text_pair字段动态检索搜索请求中的查询文本（multi_match.query）。
text（文档facts）和text_pair（搜索query）的组合使交叉编码器模型能够比较文档与查询的相关性，考虑它们的语义关系。
output_map字段指定如何将模型的输出映射到响应中的字段：rank_score字段在响应中存储模型的相关性分数，该分数将用于执行重排。
使用by_field重排类型时，rank_score字段将包含与_score字段相同的分数。要从搜索结果中移除rank_score字段，请将remove_target_field设置为true。通过设置keep_previous_score为true，可以包含重排前的原始BM25分数，以便进行调试。这使您能够将原始分数与重排后的分数进行比较，以评估搜索相关性的改进情况。
要创建搜索管道，请发送以下请求：
PUT /_search/pipeline/my_pipeline
{
"response_processors": [
{
"ml_inference": {
"tag": "ml_inference",
"description": "This processor runs ml inference during search response",
"model_id": "<model_id_from_step_3>",
"function_name": "REMOTE",
"input_map": [
{
"text": "facts",
"text_pair":"$._request.query.multi_match.query"
}
],
"output_map": [
{
"rank_score": "$.score"
}
],
"full_response_path": false,
"model_config": {},
"ignore_missing": false,
"ignore_failure": false,
"one_to_one": true
},
"rerank": {
"by_field": {
"target_field": "rank_score",
"remove_target_field": true,
"keep_previous_score" : true
}
}
}
]
}
步骤5：使用重排进行搜索
使用以下请求搜索索引文档并使用交叉编码器模型对它们进行重排。该请求检索在description或facts字段中包含任何指定术语的文档。然后使用这些术语来比较和重排匹配的文档：
POST /nyc_areas/_search?search_pipeline=my_pipeline
{
"query": {
"multi_match": {
"query": "artists art creative community",
"fields": ["description", "facts"]
}
}
}
在响应中，previous_score字段包含文档的BM25分数（如果您没有应用管道，它将获得该分数）。请注意，虽然BM25将”Astoria”排名最高，但交叉编码器模型优先考虑了”Harlem”，因为它匹配了更多搜索术语：
{
"took": 4,
"timed_out": false,
"_shards": {
"total": 1,
"successful": 1,
"skipped": 0,
"failed": 0
},
"hits": {
"total": {
"value": 3,
"relation": "eq"
},
"max_score": 0.03418137,
"hits": [
{
"_index": "nyc_areas",
"_id": "4",
"_score": 0.03418137,
"_source": {
"area_name": "Harlem",
"description": "Harlem is a historic neighborhood in Upper Manhattan, known for its significant African-American cultural heritage.",
"previous_score": 1.6489418,
"borough": "Manhattan",
"facts": "Harlem was the birthplace of the Harlem Renaissance, a cultural movement that celebrated Black culture through art, music, and literature.",
"population": 116000
}
},
{
"_index": "nyc_areas",
"_id": "1",
"_score": 0.0090838,
"_source": {
"area_name": "Astoria",
"description": "Astoria is a neighborhood in the western part of Queens, New York City, known for its diverse community and vibrant cultural scene.",
"previous_score": 2.519608,
"borough": "Queens",
"facts": "Astoria is home to many artists and has a large Greek-American community. The area also boasts some of the best Mediterranean food in NYC.",
"population": 93000
}
},
{
"_index": "nyc_areas",
"_id": "3",
"_score": 0.0032599436,
"_source": {
"area_name": "Williamsburg",
"description": "Williamsburg is a trendy neighborhood in Brooklyn known for its hipster culture, vibrant art scene, and excellent restaurants.",
"previous_score": 1.5632852,
"borough": "Brooklyn",
"facts": "Williamsburg is a hotspot for young professionals and artists. The neighborhood has seen rapid gentrification over the past two decades.",
"population": 150000
}
}
]
},
"profile": {
"shards": []
}
}