mongodb query performance

Tags: blog http io os using java ar for file"Suzhou needs to work to add me QQ, the introduction of fee-splitting" MongoDB advanced1. Database commandsA. How the command worksDrop command to delete a collection in the shell and Execute Db.refactor.drop (). Actually, this function actually runs the drop command,You can use RunCommand to achieve the same effect:Db.runcommand ({"Drop": "Refactor"}){"Nindexeswas": 1, "MSG": "Indexes dropped for collection

I. Software environment (version not required) PHP v5.6 extension: MongoDB nginx v1.11 MongoDB v3.2Note: MongoDB extensions must be installedIi. Connection $client = new Mongoclient ($server, $option);$server variable is a string that describes the server to which you want to connectMongodb://[username:[email protected]]host1[:p ort1][,host2[:p ort2:],...] /dbIt

Inserting more than one test data> for (i=1;i... db.blog.insert ({"title": I, "content": "MongoDB Test article. "," name ":" Liu "+i});... }Db.blog.list.find (). Limit ((). ForEach (function (data) {print ("title:" +data.title);}) Cyclic foreach usageDb.blog.findOne (); Fetch a piece of dataDb.blog.find (); take more than one dataDb.blog.remove (); Delete a data setDb.blog.drop (); Delete tableTo delete a database:1.use dbname2.db.dropdatabase ()=====

UPDATETblscoreSETTblscore. Score=(--Here we start with the average of cotyledons.SELECT AVG(TT.AA) from (SELECTTblscore. Score AA fromTblscoreWHERETblscore. CourseID=( SELECTTblcourse. CourseID fromTblcourseWHERETblcourse. CourseID=(SELECTTblteacher. Teaid fromTblteacherWHERETblteacher. Teaname='cotyledons')) TT--figure out the average of cotyledons courses ) WHERETblscore. CourseID= (SELECTTblcourse. CourseID fromTblcourseWHERETblcourse. CourseID=(SELECTTblteacher. Teaid fromTblteacherWHERE

example, querying ageDb.users.find ({age:{$lt: ()}) Db.users.find ({age:{$gt:()})Db.users.find ({age:{$lte:]}) Db.users.find ({age:{$gte:22}})1.3 The logical OR operator is represented using $or, and the format is{$or: [{For example, querying all the user age=21 or age=22Db.users.find ({$or: [{age:21},{age:22}]})1.4, the logic and operator use ",", or $and, the format is{$and: [{For example, the query name is "T1" and all the user age=21Db.users.find

I have been idle for a while recently, and I have been able to spend enough time studying code integration. Because there are too many linguistics, I gradually feel that it is meaningless. I learned a little from other groups using MongoDB. In view of this quick start, because the foundation is not very reliable, it will always be forgotten. Looking at the MongoDB authoritative guide, although it is in Engl

This article is a blog post from MongoDB core developer @ kchodorow. It is the first article about MongoDB query puzzles. It introduces some query rules and usage of range query in Array through several examples. Assume that a Collection contains the following data: {x:-5} {

MongoDB has been the most popular NoSQL, and according to Db-engines ranking the latest ranking, now MongoDB has defeated PostgreSQL leaped to the fourth place in the database ranking, after Oracle, MySQL and Microsoft SQ L Server, this article summarizes how to MongoDB performance tuning. Have you ever encountered

In the past-blogs, the topic mainly focus on the high query operation of MongoDB. In this blog, we simply study the regex expression in the mongdb. MongoDB also support the Regex query. For exampleThe expression is also able to combination with other expression.Notes:/^a/; /^a.*/; /^a.*$/has the same result, however th

We know that MongoDB is a kind of relational database, so its query method is very different from the standard Structured Query language SQL. But no matter how complicated a structure it is, when it passes through the developer's hands, it only becomes the structure that the customer wants. Today is about how to MongoDB