Migrating from Mongodb to Dynamo db

referernce: https://www.codementor.io/devops/tutorial/handling-date-and-datetime-in-dynamodb


Dynamo Db does not support multiple indexes
It supports only Hash key, hash key + range key only
Does not support native date, DateTime object

Advantage:
No worries of scaling, monitoring, security updates.
average good response.

Use unix time stamp, store as Number
Combine multiple mongo db key if required
Database denormalization
Based on query patter, create schema

Dynamo DB is  NO SQL db

Queries are slow
GetItem call as fast

Terminology
Table , Item, Attribute, Primary Key, hash attribute value, hash and range attribute values
secondary index on non key attibute value

Start the dynamo db locally
java -Djava.library.path=./DynamoDBLocal_lib -jar DynamoDBLocal.jar -help
Dynamo db port: 8000

Create table
var params = {
  TableName : "Music",
  KeySchema:[
    {AttributeName:"Artist", KeyType:"Hash"},
    {AttributeName:"SongTitle", KeyType:"Range"}
  ],
  AttributeDefinitions:[
     {AttibuteName:"Artist", AttibuteType:"S"},
     {AttibuteName:"SongTitle", AttibuteType:"S"},
  ],
  ProvisionedThroughput:{
      ReadCapacityUnits:1,
      WriteCapacityUnits: 1
  }
};
dynamodb.createTable(params, function(err, data){

});

TableStatus is should be Active

2)
var params = { TableName: "Music" }; dynamodb.describeTable(params, function(err, data) { if (err) console.log(JSON.stringify(err, null, 2)); else console.log(JSON.stringify(data, null, 2)); });

3)
var params = {}; dynamodb.listTables(params, function(err, data) { if (err) console.log(JSON.stringify(err, null, 2)); else console.log(JSON.stringify(data, null, 2)); });

4)

var params = { TableName: "Music", Item: { "Artist":"No One You Know", "SongTitle":"Call Me Today", "AlbumTitle":"Somewhat Famous", "Year": 2015, "Price": 2.14, "Genre": "Country", "Tags": { "Composers": [ "Smith", "Jones", "Davis" ], "LengthInSeconds": 214 } } }; dynamodb.putItem(params, function(err, data) { if (err) console.log(JSON.stringify(err, null, 2)); else console.log(JSON.stringify(data, null, 2)); });

primarykey is must, remaining attribute are optional

5)Condition Expressoin

var params = { TableName: "Music", Item: { "Artist":"No One You Know", "SongTitle":"Call Me Today", "AlbumTitle":"Somewhat Famous", "Year": 2015, "Price": 2.14, "Genre": "Country", "Tags": { "Composers": [ "Smith", "Jones", "Davis" ], "LengthInSeconds": 214 } }, "ConditionExpression": "attribute_not_exists(Artist) and attribute_not_exists(SongTitle)" };

6)Batch insert
var params = { RequestItems: { "Music": [ { PutRequest: { Item: { "Artist": "No One You Know", "SongTitle": "My Dog Spot", "AlbumTitle":"Hey Now", "Price": 1.98, "Genre": "Country", "CriticRating": 8.4 } } }, { PutRequest: { Item: { "Artist": "No One You Know", "SongTitle": "Somewhere Down The Road", "AlbumTitle":"Somewhat Famous", "Genre": "Country", "CriticRating": 8.4, "Year": 1984 } } }
]}

7)Dynamo db data types
String, number, float, map, list

8)
var params = { TableName: "Music", Key: { "Artist": "No One You Know", "SongTitle": "Call Me Today" } }; dynamodb.getItem(params, function(err, data) { if (err) console.log(JSON.stringify(err, null, 2)); else console.log(JSON.stringify(data, null, 2)); });
9)
var params = { TableName: "Music", Key: { "Artist": "No One You Know", "SongTitle": "Call Me Today" }, ProjectionExpression: "AlbumTitle" };
10)
var params = { TableName: "Music", KeyConditionExpression: "Artist = :artist", ExpressionAttributeValues: { ":artist": "No One You Know" } }; dynamodb.query(params, function(err, data) { if (err) console.log(JSON.stringify(err, null, 2)); else console.log(JSON.stringify(data, null, 2)); });

11)

var params = { TableName: "Music" }; dynamodb.scan(params, function(err, data) { if (err) console.log(JSON.stringify(err, null, 2)); else console.log(JSON.stringify(data, null, 2)); });

Operations

12)

var params = { TableName: "Music", AttributeDefinitions:[ {AttributeName: "Genre", AttributeType: "S"}, {AttributeName: "Price", AttributeType: "N"} ], GlobalSecondaryIndexUpdates: [ { Create: { IndexName: "GenreAndPriceIndex", KeySchema: [ {AttributeName: "Genre", KeyType: "HASH"}, {AttributeName: "Price", KeyType: "RANGE"}, ], Projection: { "ProjectionType": "ALL" }, ProvisionedThroughput: { "ReadCapacityUnits": 1,"WriteCapacityUnits": 1 } } } ] }; dynamodb.updateTable(params, function(err, data) { if (err) console.log(JSON.stringify(err, null, 2)); else console.log(JSON.stringify(data, null, 2)); });

13)
var params = { TableName: "Music", Key: { "Artist":"No One You Know", "SongTitle":"Call Me Today" }, UpdateExpression: "SET RecordLabel = :label", ExpressionAttributeValues: { ":label": "Global Records" }, ReturnValues: "ALL_NEW" }; dynamodb.updateItem(params, function(err, data) { if (err) console.log(JSON.stringify(err, null, 2)); else console.log(JSON.stringify(data, null, 2)); });

15)Automatic counter

15)
var params = { TableName: "Music", Key: { Artist: "The Acme Band", SongTitle: "Look Out, World" } }; dynamodb.deleteItem(params, function(err, data) { if (err) console.log(JSON.stringify(err, null, 2)); else console.log(JSON.stringify(data, null, 2)); });

http://docs.aws.amazon.com/amazondynamodb/latest/developerguide/BestPractices.html

refernce: http://docs.aws.amazon.com/amazondynamodb/latest/gettingstartedguide/GettingStarted.Java.html