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Created Jan 23, 2019

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Example Schema

Example API DynamoDB Spec

The table design for an Example API service

Table of Contents

Table Spec

Params to create the table using the CLI or the AWS SDK:
{
  "AttributeDefinitions": [
    {
      "AttributeName": "pk",
      "AttributeType": "S"
    },
    {
      "AttributeName": "sk",
      "AttributeType": "S"
    }
  ],
  "TableName": "example-api-table",
  "KeySchema": [
    {
      "AttributeName": "pk",
      "KeyType": "HASH"
    },
    {
      "AttributeName": "sk",
      "KeyType": "RANGE"
    }
  ],
  "ProvisionedThroughput": {
    "ReadCapacityUnits": 5,
    "WriteCapacityUnits": 5
  },
  "GlobalSecondaryIndexes": [
    {
      "KeySchema": [
        {
          "AttributeName": "selector",
          "KeyType": "HASH"
        },
        {
          "AttributeName": "data",
          "KeyType": "RANGE"
        }
      ],
      "IndexName": "CycleSelector",
      "Projection": {
        "ProjectionType": "ALL"
      }
    }
  ]
}

createTable Using the CLI:

$ aws dynamodb create-table --table-name example-api-table --cli-input-json create-table.json

Using the AWS SDK:

const DynamoDB = require("aws-sdk/clients/dynamodb");

const service = new DynamoDB({ region: process.env.AWS_REGION });

service.createTable(tableJson, (err, data) => {
  console.log(data);
});

Access Patterns

Get all items reserved for a global cycle, ordered by score

Provides the ability to release new items to everyone in a specific week

Perform a DocumentClient.query against the CycleSelector index:

{
  "TableName": "example-api-table",
  "KeyConditionExpression": "#selector = :selector",
  "ExpressionAttributeNames": {
    "#selector": "selector"
  },
  "ExpressionAttributeValues": {
    ":selector": "global-cycle:5"
  },
  "ScanIndexFoward": false,
  "IndexName": "CycleSelector"
}

Matching Records

selector (HASH) data (RANGE)
global-cycle:5 80 pk: item-65 sk: metadata
global-cycle:5 70 pk: item-55 sk: metadata

Get all items reserved for the user's cycle #, ordered by score

Provides the ability to reserve items for a specific week in the user's journey

Perform a DocumentClient.query against the CycleSelector index:

{
  "TableName": "example-api-table",
  "KeyConditionExpression": "#selector = :selector",
  "ExpressionAttributeNames": {
    "#selector": "selector"
  },
  "ExpressionAttributeValues": {
    ":selector": "user-cycle:1"
  },
  "ScanIndexFoward": false,
  "IndexName": "CycleSelector"
}

Matching Records

selector (HASH) data (RANGE)
user-cycle:1 35 pk: item-84 sk: metadata

Get all items in the back catalogue

Items are duplicated across all write-sharded keys

Perform a DocumentClient.query against the CycleSelector index:

{
  "TableName": "example-api-table",
  "KeyConditionExpression": "#selector = :selector",
  "ExpressionAttributeNames": {
    "#selector": "selector"
  },
  "ExpressionAttributeValues": {
    ":selector": "back-catalogue:4"
  },
  "IndexName": "CycleSelector"
}

Matching Records

selector (HASH) data (RANGE)
back-catalogue:4 87 pk: item-45 sk: metadata

Get all items currently assigned to a user, ordered by score

Perform a DocumentClient.query against the Main index with a begins_with(#sk, :sk) condition on the sort key:

{
  "TableName": "example-api-table",
  "KeyConditionExpression": "#pk = :pk and begins_with(#sk, :sk)",
  "ExpressionAttributeNames": {
    "#pk": "pk",
    "#sk": "sk"
  },
  "ExpressionAttributeValues": {
    ":pk": "user-8790",
    ":sk": "item:assigned:"
  },
  "ScanIndexFoward": false
}

Matching Records

pk (HASH) sk (RANGE)
user-8790 item:assigned:350 itemId: item-84
user-8790 item:assigned:87 itemId: item-45

Get all completed items by a user, ordered by completed date

Perform a DocumentClient.query against the Main index with a begins_with(#sk, :sk) condition on the sort key:

{
  "TableName": "example-api-table",
  "KeyConditionExpression": "#pk = :pk and begins_with(#sk, :sk)",
  "ExpressionAttributeNames": {
    "#pk": "pk",
    "#sk": "sk"
  },
  "ExpressionAttributeValues": {
    ":pk": "user-8790",
    ":sk": "item:completed:"
  },
  "ScanIndexFoward": false
}

Matching Records

pk (HASH) sk (RANGE)
user-8790 item:completed:2019-01-22T11:15:00.000Z itemId: item-102
user-8790 item:completed:2019-01-22T10:28:49.930Z itemId: item-55

Get in-progress item for a user

Perform a DocumentClient.get against the Main index:

{
  "TableName": "example-api-table",
  "Key": {
    "pk": "user-8790",
    "sk": "item:in-progress"
  }
}

Matching Records

pk (HASH) sk (RANGE)
user-8790 item:in-progress itemId: item-3 progress: 0.87

Get all orphaned items for a user, ordered by orphan time

Perform a DocumentClient.query against the Main index with a begins_with(#sk, :sk) condition on the sort key:

{
  "TableName": "example-api-table",
  "KeyConditionExpression": "#pk = :pk and begins_with(#sk, :sk)",
  "ExpressionAttributeNames": {
    "#pk": "pk",
    "#sk": "sk"
  },
  "ExpressionAttributeValues": {
    ":pk": "user-8790",
    ":sk": "item:orphaned:"
  }
}

Matching Records

pk (HASH) sk (RANGE)
user-8790 item:orphaned:2018-12-25T11:15:00.000Z itemId: item-34

Get stats for a user

Perform a DocumentClient.get against the Main index:

{
  "TableName": "example-api-table",
  "Key": {
    "pk": "user-8790",
    "sk": "stats"
  }
}

Matching Records

pk (HASH) sk (RANGE)
user-8790 stats completed: 55 correctGuesses: 24 liveCompleted: 4

Indexes

Main

pk (HASH) sk (RANGE)
item-55 metadata selector: global-cycle:5 data: 70
item-65 metadata selector: global-cycle:5 data: 80
item-84 metadata selector: user-cycle:1 data: 35
item-3 metadata selector: back-catalogue data: 99
item-45 metadata selector: back-catalogue:4 data: 87
user-8790 item:assigned:87 itemId: item-45
user-8790 item:assigned:350 itemId: item-84
user-8790 item:completed:2019-01-22T10:28:49.930Z itemId: item-55
user-8790 item:completed:2019-01-22T11:15:00.000Z itemId: item-102
user-8790 item:in-progress itemId: item-3 progress: 0.87
user-8790 item:orphaned:2018-12-25T11:15:00.000Z itemId: item-34
user-8790 stats completed: 55 correctGuesses: 24 liveCompleted: 4

CycleSelector

selector (HASH) data (RANGE)
global-cycle:5 70 pk: item-55 sk: metadata
global-cycle:5 80 pk: item-65 sk: metadata
user-cycle:1 35 pk: item-84 sk: metadata
back-catalogue 99 pk: item-3 sk: metadata
back-catalogue:4 87 pk: item-45 sk: metadata

Author

Spec authored by Eric Allam and generated by dynamodb-spec-generator

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