Mongodb index commands with examples

Create OR Use existing Database

use bank;

Create a new collection.

db.createCollection("users");

Add Records in collection.

db.users.insert([{"isActive":false,"balance":"$3,960.64","age":30,"eyeColor":"blue","name":"Dawn Keith","gender":"female","company":"COSMOSIS","email":"dawnkeith@cosmosis.com","phone":"+1 (839) 437-3421","address":"392 Clifford Place, Fontanelle, Arizona, 2687"},{"isActive":false,"balance":"$1,280.14","age":31,"eyeColor":"green","name":"Bettie Eaton","gender":"female","company":"COMTREK","email":"bettieeaton@comtrek.com","phone":"+1 (861) 460-2317","address":"203 Allen Avenue, Elrama, North Carolina, 4453"},{"isActive":true,"balance":"$2,042.37","age":38,"eyeColor":"green","name":"Margie Ayala","gender":"female","company":"VOIPA","email":"margieayala@voipa.com","phone":"+1 (941) 569-2231","address":"111 Schroeders Avenue, Suitland, Louisiana, 7042"},{"isActive":false,"balance":"$3,170.35","age":37,"eyeColor":"blue","name":"Baker Townsend","gender":"male","company":"EVIDENDS","email":"bakertownsend@evidends.com","phone":"+1 (808) 500-2793","address":"190 Just Court, Canoochee, Alabama, 325"}]);

Get all records

db.users.find().pretty();

Analyse the Query

db.users.find().explain("executionStats");

Add Index on collection

db.users.ensureIndex({"age":1});

Get all indexes on collection.

db.users.getIndexes();

Output

[
  {
    "v": 1,
    "key": {
      "_id": 1
    },
    "name": "_id_",
    "ns": "bank.users"
  },
  {
    "v": 1,
    "key": {
      "age": 1
    },
    "name": "age_1",
    "ns": "bank.users"
  }
]

Delete Index on collection.

db.users.dropIndex({"age":1});

Output

{
  "nIndexesWas": 2,
  "ok": 1
}

Drop all indexes.

db.users.dropIndexes();

Output

{
  "nIndexesWas": 1,
  "msg": "non-_id indexes dropped for collection",
  "ok": 1
}

Check Indexes, after droping an index.

db.users.getIndexes();

Output

[
  {
    "v": 1,
    "key": {
      "_id": 1
    },
    "name": "_id_",
    "ns": "bank.users"
  }
]

ReIndex the collecton.

db.users.reIndex()

Output

{
  "nIndexesWas": 1,
  "nIndexes": 1,
  "indexes": [
    {
      "key": {
        "_id": 1
      },
      "name": "_id_",
      "ns": "bank.users"
    }
  ],
  "ok": 1
}

Simple Aggregate Example

db.users.aggregate({$group:{_id:"$age",total:{$sum:1}}});

Output

{
  "_id": 37,
  "total": 1
}{
  "_id": 38,
  "total": 1
}{
  "_id": 31,
  "total": 1
}{
  "_id": 30,
  "total": 2
}

Average Aggregate Example

db.users.aggregate({$group:{_id:"$gender",avgAge:{$avg:"$age"}}});

Output

{
  "_id": "female",
  "avgAge": 32.25
}{
  "_id": "male",
  "avgAge": 37
}

Max Value in Aggregate

db.users.aggregate({$group:{_id:"$gender",richest:{$max:"$balance"}}});

Output

{
  "_id": "female",
  "richest": "$3,960.64"
}{
  "_id": "male",
  "richest": "$3,170.35"
}

Best Related Posts are Following:

1. MongoDB Interview Questions and Answer for 1 Year Experienced.
2. MongoDB operators with examples.
3. MongoDb PHP functions Questions and Answers.
4. How to Configure MongoDB with PHP for WampServer on Windows.
5. MongoDb Technical Interview Questions and Answers.
6. MongoDB Interview Questions and Answers.
7. How to install MongoDB install on window 7.
8. MongoDB - Where and Why should we use MongoDb?.
9. Advance MongoDB Interview Questions and Answer.
10. MongoDB Interview Questions and Answer on Database.

Download the media files with node in Azure serverless

Pre-requisite for Node in Azure Serverless 

1. You have created a function with with name "download-files"
2. You have downloaded ffmpeg files (ffmpeg.exe) in "site -> wwwroot-> bin"
3. You have created a folder with name wav_to_mp3 "site -> wwwroot-> wav_to_mp3"

Source Code

//Download the Required module
const http = require('https');
const fs = require('fs');
//const childProcess = require('child_process');
const path = require('path');

//Define constants
const VIDEO_PATH = 'wav_to_mp3/';
const ffmpegLib='bin/ffmpeg';

module.exports =  function (context, req) {
    ////////////// params declaration
    let bodyData=req.body;
    let tourStreamName=bodyData.tour_stream_name;
    let videoUrls=bodyData.url;
    
    let filename='';
    let filenameSuccessLog={};
    let completedCounter=0;
    if (tourStreamName && videoUrls.length>0) {
        ////////////////////// ALL VIDEOS DOWNLOAD ////////////////////////////
        //const forLoop = async _ => {
         videoUrls.forEach(async (url) => {
              filename=path.basename(url); 
             // let videoDownload=VIDEO_PATH+filename;
                //full video url, filename, force download
                downloadFileAsync(url,filename,0).then(data=>{  
                   filenameSuccessLog[data.filename]=data.success;
                   completedCounter++;
                   if(videoUrls.length==completedCounter){
                       messageData(200,{success:1,'msg':'',result:filenameSuccessLog});
                   }                    
               }); 
          })
        //}    
         //forLoop();
        ////////////////////// ALL VIDEOS DOWNLOAD ////////////////////////////

    } else {
        messageData(200,{success:0,msg:"Parameter missing (tour_stream_name OR url)",'result':{}});
    }
    
    
    
    //for print the message
    function messageData(statusCode,message){
        context.res = {
            status: statusCode,
            body: message,
            headers: {
                'Content-Type': 'application/json'
            }
        };   
         context.done();
               
    } 
    
};



///////////////////////////// Other Functions ////////////////////////////////////
/**
 * @url: url of video
 * @destination: file with name download in wav_to_mp3
 * @forcedownload: 1 means download again even
 */
async function downloadFileAsync(url, destination,forcedownload) {
    return new Promise(function(resolve, reject) {
        let result={success:0,'msg':'',filename:destination};
        if (fs.existsSync(VIDEO_PATH+destination) && forcedownload==0) {
            result.success=1
            resolve(result);            
        }else{
            const file = fs.createWriteStream(VIDEO_PATH+destination);
            const request = http.get(url, (res) => {
              res.pipe(file);
            });
            request.once('error', (error) => 
              {
                  result.msg=error;
                  reject(result);
              }
            );
            file.once('finish', () => 
              {
                result.success=1
                resolve(result);
              }
            );             
        }
       
        
    })
}

///////////////////////////// Other Functions ////////////////////////////////////

URL: https://function-name.azurewebsites.net/api/download-files
Method: POST
Request:

{"tour_stream_name":"arun","url":["https://example.com/video/0_20190821064650782.mp4","https://example.com/video/tq_33038dev-GM-ma9kW-1106-26079.mp4"]}

Response:

{
    "success": 1,
    "msg": "",
    "result": {
        "tq_33038dev-GM-ma9kW-1106-26079.mp4": 1,
        "0_20190821064650782.mp4": 1
    }
}