mongodb query performance

: Using Mongodb.bson;Using Mongodb.driver; To perform data operations, first instantiate a mongoclient var client = new Mongoclient ("mongodb://127.0.0.1:27017"); Then create DATABASE and collection var database = client. Getdatabase ("foo");var collection = database. Getcollection Then we can try to insert a piece of data, the code is as follows var document = new Bsondocument{{"Name", "SQL Server

, just use one point. More detailed can see this link: dot notationAs an example:> Db.blog.save ({title: "My first Post", Author: {Name: "Jane", Id:1}})If we want to query authors name is Jane, we can do this:> Db.blog.findOne ({"Author.name": "Jane"})If not, then you need to use the following sentence to match:Db.blog.findOne ({"Author": {"name": "Jane", "id": 1}})The following sentence:Db.blog.findOne ({"Author": {"name": "Jane"}})is not matched, be

Db.app_users.aggregate ([{ $project:{ fs:1,ls:1, subt:{$subtract: [' $ls ', ' $fs ']}, days714:{ $cond: [ { $gte: [' $ls ', (Math.Round (Newdate ()). GetTime () /1000) -14*24*60*60)]},1,0] }, days1430:{ $cond:[ { $and:[ { $lte: [' $ls ', (Math.Round (Newdate ()). GetTime () /1000) -14*24*60*60)]}, { $gte: [' $ls ', (Math.Round (Newdate ()). GetTime () /1000) -30*24*60*60)]} ]} ,1,0]}, days30:{ $cond:[{ $lte: [ ' $ls ', (Math.Round ((Newdate ()). GetTime () /1000) -30*24*60*60)]},1,0] }, days81

There are a lot of blog posts about how to take a single record out of a MongoDB library, including the following three ways:1. Skip a random number of records.dbcursor cursor = coll.find (query), int rint = Random.nextint (Cursor.count ()), Cursor.skip (rint);D bobject word = null;if ( Cursor.hasnext ()) {word = Cursor.next (); Cursor.close ();}Many people say that this is not recommended, if the amount of

Label:Ruby on Rails is well-integrated with MongoDB, the Gem pack: Address:https://rubygems.org/gems/mongoid Documentation: https://docs.mongodb.com/ecosystem/tutorial/ruby-mongoid-tutorial/#ruby-mongoid-tutorial Latest queries that are also used Model.where (name:/abc/) This can look up all the contents of the Name field in the model table with ABC. Pagination, can be combined with willpage defSelf.paginate (options ={}) options[:p age]=options[:p a

Query errors caused by corrupted MongoDB index files Problem description: When MongoDB is disabled abnormally, the index file may be damaged, and the data is not reflected in the index when the data is updated. Solution: Use scripts to recreate indexes of all MongoDB tables. Var names = db. getCollectionNames ();

[Switch] The internal implementation of IMongoQuery in MongoDB C #/. NET Driver, MongoDB is a product between relational databases and non-relational databases. It has the most abundant functions and features like relational databases. The supported data structure is very loose and is similar to the json bjson format. Therefore, it can store complicated data types. The biggest feature of Mongo is that it su

",...," Coln ":" column value n "}) 2. find 2.1 All queries Syntax: db. Set. find () 2.2 conditional Query Syntax: db. Set. find ({"Col1": "column value 1", "Col2": "column value 2 ",...," Coln ":" column value n "}) Operation example: Add + search Note: The "_ id" field is the GUID that the database uses by default to ensure data uniqueness. 3. Modify 3.1 modify update all Syntax: db. Set. update ({"Col": "column value" },{ "Col2": "column value 2 "

Tags: command configuration file version Server insertI. PrincipleThe principle of Zabbix monitoring MongoDB is through echo "Db.serverstatus ()" | MONGO Admin to see the status of MongoDBTwo Server Configuration1) Add global variables for MONGO# vim/etc/profile.d/mongo.shExport Path=/usr/local/mongodb/bin: $PATH# . /etc/profile.d/mongo.sh2) After execution you can see some status information of

[Root @ localhost ~] # Export mongodbshellversion: 1.8.1connectingto: testgt; dbtestgt; showcollections [Root @ localhost ~] # Mongo MongoDB shell version: 1.8.1 connecting to: test gt; db test gt; show collections [Root @ localhost ~] # MongoMongoDB shell version: 1.8.1Connecting to: test> DbTest> Show collectionsData_testSystem. indexesSystem. users> Db. data_test.find (). skip (3). limit (4) // query