DynamoDB Descending Order fetch records

Question

i have 100 records in collection,

collection name:'users'

{
   "name":'senthilkumar',  
   "email":'[email protected]',  //HashKey
   "age":21,
   "created":1465733486137,         //RangeKey-timestamp
}

i need to fetch records the following sql query wise

select * from users order by created desc limit 10

How i can get above query format records from DynamoDB

Answer 1

Dynamodb sorts the results by the range key attribute. You can set the ScanIndexForward boolean parameter to true for ascending or false for descending.

resource: http://docs.aws.amazon.com/amazondynamodb/latest/APIReference/API_Query.html

Use the KeyConditionExpression parameter to provide a specific value for the partition key. The Query operation will return all of the items from the table or index with that partition key value. You can optionally narrow the scope of the Query operation by specifying a sort key value and a comparison operator in KeyConditionExpression. You can use the ScanIndexForward parameter to get results in forward or reverse order, by sort key.

Answer 2

To Save Json Data to DynamoDB us put()

var Newparams = {
    TableName: this.SuffleTableName,
       Item: {
        "userId": /* YOUR PRIMARY KEY */,
        "addedAt": /* YOUR SORT KEY */,
        "status": /* Additional Datas */,
       }
}

Fetch Data From DynamoDB using Query()

  QueryParam = {
       TableName: 'YOUR TABLE NAME HERE',
       IndexName: 'YOUR INDEX NAME HERE', //IF YOUR CREATED NEW INDEX
       KeyConditionExpression: "UserId = :UserId  ", //YOUR PRIMARY KEY
       ExpressionAttributeValues: {
          ":UserId": UserId,
       },
       ScanIndexForward: false, //DESC ORDER, Set 'true' if u want asc order 
       ExclusiveStartKey: LastEvalVal, //Pagination - LastEvaluatedKeyPair
       Limit: 10 //DataPerReq
    }