Node.js AWS DynamoDB Scan specific field(s) only

In many AWS DynamoDB datas, I want to search specific key-value data using node.js.

My Database single-key sample is like under.

{    "device_id" : "abcde12345", // Primary Key, String    "setting": {      "left_motor": 30,      "right_motor": 30,      "motor_name": "STRING_WHAT_I_WANT_TO_CHECK"    },    "another_fields1" : "1234",    "another_fields2": {      "key1" : 1,      "key2" : "2",      "key3" : { ... }    }  }  

My code for collect all of item's motor_name is like under.

// require modules  var fs       = require('fs'); // used for save json-result.  var AWS      = require('aws-sdk');  var config   = require('./config_file'); // secret data  var schedule = require('node-schedule');    AWS.config.update({    region: config.dynamodb.region,    endpoint: config.dynamodb.endpoint,    accessKeyId: config.dynamodb.access_key,    secretAccessKey: config.dynamodb.secret_key  });    var documentClient = new AWS.DynamoDB.DocumentClient();    var params = {    TableName: config.dynamodb.device_table  };    // I set run once at 9 o'clock, but after do single-time, I kill pm2 process.  // (just for run once only)    var motor_name_list = {}; // result will be saved.  var j = schedule.scheduleJob("0 0 9 * * *", function() {    documentClient.scan(params, onScan);  });    function onScan(err, data) {    if(err) {      console.log(err);    }    else { // READ SUCCESS      /*        'single_item' sample is like upper json-code         But, I reference only one value, setting.motor_name      */      data.Items.forEach(function(single_item) {        // process scan success datas        var motor_name = single_item.setting.motor_name;        if(motor_name_list.hasOwnProperty(motor_name))          motor_name_list[motor_name] += 1;        else          motor_name_list[motor_name] = 1;      });           if(typeof data.LastEvaluatedKey != 'undefined') {        params.ExclusiveStartKey = data.LastEvaluatedKey;          // Because of Read Limit per minute, I delay next-step for one minute.        // (maybe, ReadCapacityUnits)        setTimeout(function() {          documentClient.scan(params, onScan);        }, 60 * 1000);      }      else {        // save motor_name_list as a file (fs.writeFileSync...)      }    } // END OF READ SUCCESS  }  

Because of delay, It takes a lot of time. (10~15 minutes, in fact).
(single onScan reads 300~500 items and I have almost 5000 items.

Is there any possible way to scan only single-item without change my json format?

Thank you for read my Question.

https://stackoverflow.com/questions/66773393/node-js-aws-dynamodb-scan-specific-fields-only March 24, 2021 at 09:07AM