sort-投影 //18.查询numbers中num为500的文档 db.numbers.find({num:500}) //19.查询numbers中num大于5000的文档 db.numbers.find({num:{$gt:500}}); db.numbers.find({num:{$eq:500}}); //20.查询numbers中num小于30的文档 db.numbers.find({num:{$lt:30}}); //21.查询numbers中num大于40小于...
db.mycoll.find(...).skip(n) db.mycoll.find(...).sort(...) db.mycoll.findOne([query]) db.mycoll.findAndModify( { update : ... , remove : bool [, query: {}, sort: {}, 'new': false] } ) db.mycoll.getDB() get DB object associated with collection db.mycoll.getPlanCach...
db.getCollection('users').find({username:"user2500000"}).sort({"username":-1}).explain("executionStats") 5.3 复合索引 db.users.createIndex({"age":1,"username":1}) db.users.find({"age":{"$gte":21, "$lte":30}}).sort({"username":1}).limit(10000).explain("executionStats") db.g...
$sort stage : sorts the results by year ascending. $unwind stage : splits each movie document into multiple documents, one for each cast member in the original document. For each original document, this stage unwinds the Cast array of cast members and creates separate, unique documents with ...
Atlas Search (available inMongoDB Atlas) supports multiple full-text search indexes on a single collection. To learn more, see theAtlas Search documentation. To create atextindex, use thedb.collection.createIndex()method. To index a field that contains a string or an array of string elements,...
NamePathTypeDescription documents documents array of object documents items documents object Insert DocumentOperation ID: InsertDocument Using the insertOne endpoint, you can add a document to a collection. Use the document property in the request body to specify the document that should be created....
MongoDB使用BSON文件存储在collection中,本文主要介绍MongoDB中的写操作和优化策略。 主要有三种写操作: Create Update Delete Create:可以分为两种基本操作——insert和updates with the upsert option Insert() BSON文件最大为16M;_id通常作为主key 为了测试写操作是否成功,可以调用getLastError函数{ getLastError: 1 ...
cursor.sort() Yes Yes Yes No cursor.tailable() No No No No cursor.toArray() Yes Yes Yes No * Index hint is supported with index expressions. For example, db.foo.find().hint({x:1}). Aggregation pipeline operators Topics Accumulator expressions Arithmetic operators Array operators Bool...
db.<collection>.getPlanCache().getPlansByQuery({"query": {"name": "testname"}, "sort": { "name": 1 }) queryHash and planCacheKey MongoDB 4.2 or later introduces queryHash to define query shapes. Each query shape is associated with a queryHash value. MongoDB 4.2 or later also int...
Learn about the $map aggregation operator, which applies an expression to each item in an array and returns an array with the applied results.