Introduction

A batch sink that pushes data from hydrator pipelines into dynamoDb tables.

Use case(s)

• An organization wants to parse the logs generated by a system and want to store the metadata in dynamodb tables.

User Storie(s)

• • User should be able to provide the table name in DynamoDb. 
  • User should be able to provide the primary key of the table. 
  • User should be able to provide the type of primary key (hash or range).
  • The table should be created if it is not already existing. 
  • User should be able to provide the AWS endpoint url for DynamoDb instance.
  • User should be able to provide the AWS region id for DynamoDb instance.
  • User should be able to provide the AWS access id.
  • User should be able to provide the AWS access key.

Plugin Type

•  Batch Source
•  Batch Sink 
•  Real-time Source
•  Real-time Sink
•  Action
•  Post-Run Action
•  Aggregate
•  Join
•  Spark Model
•  Spark Compute

Configurables

This section defines properties that are configurable for this plugin. 

Design / Implementation Tips

• • For Testing purposes tables can be created either using AWS cli or using java code http://docs.aws.amazon.com/amazondynamodb/latest/developerguide/JavaDocumentAPITablesExample.html
  • AWS dynamoDb cli refrence http://docs.aws.amazon.com/cli/latest/reference/dynamodb/
  • Java example for CRUD operations http://docs.aws.amazon.com/amazondynamodb/latest/developerguide/batch-operation-document-api-java.html
  • Please reuse/modify RecordReader, InputFormat classes present here https://github.com/awslabs/emr-dynamodb-connector

Design

DynamoDB Sink JSON format:

{
     "name": "DynamoDb",
     "type": "batchsink",
     "properties": {
         "endpointUrl": "",
         "regionId": "us-east-1",
         "accessKey": "xyz",
         "secretAccessKey": "abc",
         "tableName": "Movies",
         "primaryKeyFields": "Id:N",
         "primaryKeyTypes": "Id:HASH",  
         "readCapacityUnits": "10",
         "writeCapacityUnits": "10"
    }
}

Approach(s)

1. Dropdown with the list of regions will be provided to user, to select the region for AWS Dynamo DB to connect to. Supported regions are:          
   "us-gov-west-1", "us-east-1", "us-east-2", "us-west-1", "us-west-2", "eu-west-1", "eu-west-2", "eu-central-1", "ap-south-1","ap-southeast-1", "ap-southeast-2", "ap-northeast-1", "ap-northeast-2", "sa-east-1", "cn-north-1", "ca-central-1", "getCurrentRegion".   (Referred from: http://docs.aws.amazon.com/AWSJavaSDK/latest/javadoc/
   http://docs.aws.amazon.com/general/latest/gr/rande.html#ddb_region)
   
   
2. If user does not select any region, then default region will be used, i.e. us_-west_-2.
   
   
3. getCurrentRegion from the list, returns a Region object representing the region the application is running in, when running in EC2. If this method is called from a non-EC2 environment, it will return null.
   
   
4. The plugin will support following CDAP data types in schema:   String, Number(int, long, float, double), Boolean, NULL, Map, List, Array of String and Array of Number, Bytes (will be converted to binary when storing to DynamoDB).
   
   
5. Key value drop-down to take the name of the primary key fields and attribute type. The drop-down will allow following values: String, Number(int, long, float, double), Boolean, NULL, Map, List, Array of String and Array of Number.
   
   
6. Key value drop-down to take the name of the primary key fields and key type. The drop-down will have the following values: "N"(number), "S"(string) and "B"(binary - the byte[] value received from the previous stage will be converted to binary when storing the data in DynamoDB).
   
   
7. The plugin will retry to put data 3 times before failing.
   
   

8. max batch size = 25 , max individual item size = 400 KB, total request size for each batch = 16MB  

   (http://docs.aws.amazon.com/amazondynamodb/latest/APIReference/API_BatchWriteItem.html)

Properties

• endpointUrl: aws endpoint http://docs.aws.amazon.com/general/latest/gr/rande.html#ddb_region This could be reconstructed using regionId.
• regionId: The region for AWS Dynamo DB to connect to.
• accessKey: Access key for AWS Dynamo DB.
• secretAccessKey: Secret access key for AWS Dynamo DB.
• tableName: The table to write the data to. If the specified table does not exists, it will be created using the primary key attributes and key schema and the read the data from.primaryKey: The field name to be used as priary keyand write capacity units.
• primaryKeyFields: A comma-separated list of key-value pairs representing the primary key and its attribute type. The attribute type can have the following values: "N"(Number), "S"(String) or "B"(binary).
• primaryKeyTypes:  A comma-separated list of key-value pairs representing the primary key and its attribute type. The key type can have the following values: "HASH" or "RANGE".
• readCapacityUnits: The maximum number of strongly consistent reads consumed per second before DynamoDB returns a ThrottlingException. This will be used when creating a new table if the table name specified by the user does not exists.
• writeCapacityUnits: The maximum number of writes consumed per second before DynamoDB returns a ThrottlingException. This will be used when creating a new table if the table name specified by the user does not exists.

Security

• The AWS access keys should be a password field and macros enabled

NFR

1.This plugin should be able to read the data from DynamoDB table and emits the structured record to next stage successfully.

2.Only Performance measurement is in scope as part of NFR.

Limitation(s)

Future Work

Test Case(s)

DynamoDB batch sink - using partition key.

DynamoDB batch sink - using partition and sort key.

DynamoDB batch sink - using 100k data

Sample Pipeline

DynamoDB Batch sink - using partition key

DynamoDb batch sink- using 100k data