dynamodb查询ExpressionAttributeValues javascript

Question

Hey guys so I'm trying to query my dynamo db GIS index for any string is more than a year old on the checkdate column, so my questions is how do you construct the KeyConditionExpression or ExpressionAttributeValues? Any help is appreciated! Refer to code below:

 console.log("Loading function"); var AWS = require('aws-sdk'); var lastyeartoday = new Date(); var dd = lastyeartoday.getDate(); var mm = lastyeartoday.getMonth()+1; var yyyy = lastyeartoday.getFullYear()-1; var ddb = new AWS.DynamoDB({apiVersion: '2012-08-10'}); var s3 = new AWS.S3(); function date(err, lastyeartoday) { if(dd<10) { dd = '0'+dd; } if(mm<10) { mm = '0'+mm; } } lastyeartoday = mm + '/' + dd + '/' + yyyy; console.log(lastyeartoday); exports.handler = function(data, context, callback) { var params = { TableName: "S3_log", IndexName: "Checkdate-index", "Select": "ALL_ATTRIBUTES", KeyConditionExpression: 'Checkdate = :checkdate', ExpressionAttributeValues: { ":checkdate": {S: lastyeartoday.toString()}, }, ScanIndexForward: true, Limit: 1, ConsistentRead: false, ReturnConsumedCapacity: 'NONE', }; ddb.query(params, function(err, data) { if (err) { callback(err, null); } else { return(null, data); }; 

Answer 1

The Query API doesn't allow greater than operator for hash key attribute.

Two approaches:-

1) Redesign the GSI to have Checkdate as sort key rather than hash key. In that case, you may need to define another attribute as hash key. Also, you need to include the hash key in KeyConditionExpression . I am not sure whether this would satisfy your use case scenario. However, if you wanted to avoid full table scan and use Query API, then you need hash key value. Without hash key value, you can't use Query API.

KeyConditionExpression: 'somenewhashkey = :hashkey AND Checkdate > :checkdate',

2) Use Scan API with FilterExpression

FilterExpression: "Checkdate > :checkdate",

Please note that this would perform full table or index scan which is a costly operation