The index stores the value of a specific field or set of fields, ordered by the value of the field. The ordering of the index entries supports efficient equality matches and range-based query operations. In addition, MongoDB can return sorted results using the ordering in the index. 大致意思...
db.collectionName.find(query,fields) 1. 1、query:查询条件 2、fields:是否显示字段查询,默认不添加,显示全部字段,{name:0}表示不显示,{name:1}只显示名称字段内容,默认_id都会显示,除非指定不显示 实例表: user 查看find方法函数 db.user.find; 1、查询全部内容 a、db.user.find() b、db.user.find({}...
The index stores the value of a specific field or set of fields, ordered by the value of the field. The ordering of the index entries supports efficient equality matches and range-based query operations. In addition, MongoDB can return sorted results using the ordering in the index. ...
Equality Match on Fields db.users.find( {"favorites.artist":"Picasso"} ) Query on Arrays When the field holds an array, you can query for an exact array match or for specific values in the array If you specify multiple conditions without using the $elemMatch operator, then some combination...
@AutowiredprivateMongoTemplatemongoTemplate;publicList<Document>querySpecificColumns(StringcollectionName,StringcolumnName){Queryquery=newQuery();query.fields().include(columnName);// 指定需要查询的列名returnmongoTemplate.find(query,Document.class,collectionName);} ...
If your application’s query patterns are known in advance, then you should use more selective indexes on the specific fields accessed by the queries. Use text search to match words inside a field Regular indexes are useful for matching the entire value of a field. If you only want to ...
A MongoDB Query Filter. The findOne action returns the first document in the collection that matches this filter. projection projection object A MongoDB Query Projection. Depending on the projection the returned document will either omit specific fields or include only specified fields or values ...
What are shard keys in MongoDB? Shard keysare based on fields inside each document. The values in those fields will decide on which shard the document will reside, according to the shard ranges and amount of chunks. This data is stored and kept in the config server replica set. ...
{ "type": "vectorSearch", "fields": [ { "numDimensions": 384, "path": "embedding", "similarity": "cosine", "type": "vector" } ] } 设置环境变量。 export OPENAI_API_KEY= 运行RAG 应用程序。 env/bin/streamlit run rag/app.py 应用程序生成的日志信息将附加到 app.log。 用法 该机器人...
Set the project property: Specifies the fields to return in the documents that match the query filter. To return all fields in the matching documents, omit this parameter. Type: string (or Expression with resultType string). Parameters: project - the project value to set. Returns: the Mo...