AWS DynamoDB Parse Server Adapter

this is database adapter to add support of AWS DynamoDB to Parse Server

Setup

Create one Table using the AWS Console or the AWS API or the AWS CLI with the following parameters

• Primary Key : _pk_className
• Sort Key : _sk_id

YOU MUST USE THESE KEYS NAME IN ORDER TO USE THIS ADAPTER!

Example creating the table using the CLI

pip install awscli                    // install awscli using python pip
aws configure set region eu-central-1 // set your aws region
aws configure                         // set your AWS Access Key ID and Secret
aws dynamodb create-table 
    --table-name parse-server 
    --attribute-definitions AttributeName=_pk_className,AttributeType=S AttributeName=_sk_id,AttributeType=S
    --key-schema AttributeName=_pk_className,KeyType=HASH AttributeName=_sk_id,KeyType=RANGE 
    --provisioned-throughput ReadCapacityUnits=500,WriteCapacityUnits=1000

Please read more about Read/Write Capacity Units here

Make sure you provision enough Capacity Units, it depends on your application, if your application is write intensive provision as twice as the read capacity units for your write capacity

The Read/Write Capacity Units can be changed anytime, but you cannot change the Primary Key and Sort Key once the table is created!

Create AWS IAM User

Learn here about how to setup an AWS IAM User and generate aws credentials

If you are using AWS EC2, I suggest using AWS IAM Roles and attach it to your EC2 Instance instead of IAM Users for better security

Usage

var DynamoDB = require('parse-server-dynamodb-adapter').DynamoDB;
var dynamo = new DynamoDB('parse-server', // your DynamoDB Table 
              { apiVersion: '2012-08-10', // AWS API Version
                region : 'eu-central-1',  // your AWS Region where you setup your DynamoDB Table
                accessKeyId: 'AK....',    // your AWS Access Key ID, ignore if you are using IAM Roles 
                secretAccessKey: 'secret' // your AWS Secret Access Key, ignore if you are using IAM Roles
               }
           );

var api = new ParseServer({
  databaseAdapter: dynamo.getAdapter(),
  appId: 'myAppId',
  masterKey: 'myMasterKey'
  serverURL: 'http://localhost:1337/parse'
  ...
});

Limits in AWS DynamoDB

Just like other databases DynamoDB has also some limits that are documented here: But the most important limits that you need to know are

• Maximum Document/Object/Item Size : 400KB (vs 16MB in MongoDB)
• Maximum number of elements in the $in query : 100 (vs as many as you want in MongoDB, as long the whole query document size doesn't exceed 16MB)
• Maximum Expression Length : 4 KB

Compatibility with Parse Server

Please remember AWS DynamoDB is mainly a key-value Database, this adapter tried its best to simulate how Parse Server works with other Databases like MongoDB, however these features or functions won't work as you expect

• Skip : You cannot use skip on your Parse.Query
• Sort : If you use ascending/descending on any key other than objectId with your Parse.Query, the sort will be applied on the query results
• containedIn : this cannot support huge array more than 98 elements when using Parse.Query
• containsAll : you can use this with bigger array however remember that you may hit the maximum length of Expression, which is limited by 4KB
• Uniqueness : This adapter impelements uniqueness on the adapter layer, so uniquness is not 100% guaranteed when inserting data in parallel
• startsWith/contains : Works with strings but not with RegEx
• endsWith : doesn't work, because DynamoDB doesn't support RegEx
• read consistency : DynamoDB has an eventually read consistency by default, but this query for the nature of Parse Server is using strong read consistency, this may come with extra AWS charges, read more about this topic here
• Array of Pointers : you can use pointers but you cannot have an array of pointers! we suggest storing only the objectId as string like this Activity.set("users",[User1.id, User2.id, ... ]") instead of Activity.set("users", [User1, User2, ... ])

Usage without Parse Server

You can use this adapter as a npm module with any project you have without Parse Server

var dynamo = new DynamoDB('my-table', // your DynamoDB Table
              { apiVersion: '2012-08-10', // AWS API Version
                region : 'eu-central-1',  // your AWS Region where you setup your DynamoDB Table
                accessKeyId: 'AK....',    // your AWS Access Key ID, ignore if you are using IAM Roles
                secretAccessKey: 'secret' // your AWS Secret Access Key, ignore if you are using IAM Ro$
               }
           );

var db = dynamo.getAdapter()
var User = db._adaptiveCollection('User');
User.insertOne({ _id : "1234", "name" : "benishak" });
User.find({ _id : "1234" });

// or using Partiton instance
var Partition = dynamo.Partition;
var User = new Partition('my-table', 'User', dynamo.adapter.service);
User.insertOne({ _id : "1234", "name" : "benishak" });
User.find({ _id : "1234" });
User.deleteOne({ _id : "1234" });

I will create a much easier API in next version of this adapter