From deec40b721ad3bb1a1ff1575897ce9228f486250 Mon Sep 17 00:00:00 2001
From: Sam Marks <sam@sammarks.me>
Date: Tue, 6 Aug 2019 11:29:21 -0400
Subject: [PATCH] fix: use DynamoDB scans instead of query

---
 serverless.yml        |  6 +-----
 src/ingest.js         |  4 +---
 src/schedule.js       |  6 ++----
 test/ingest.test.js   |  4 +---
 test/schedule.test.js | 20 +++++++++-----------
 5 files changed, 14 insertions(+), 26 deletions(-)

diff --git a/serverless.yml b/serverless.yml
index eed319d..bdc2830 100644
--- a/serverless.yml
+++ b/serverless.yml
@@ -16,7 +16,7 @@ provider:
     - Effect: Allow
       Action:
         - dynamodb:UpdateItem
-        - dynamodb:Query
+        - dynamodb:Scan
         - dynamodb:DeleteItem
       Resource:
         Fn::GetAtt: ['tasksTable', 'Arn']
@@ -44,13 +44,9 @@ resources:
         KeySchema:
           - AttributeName: taskId
             KeyType: HASH
-          - AttributeName: executeTime
-            KeyType: RANGE
         AttributeDefinitions:
           - AttributeName: taskId
             AttributeType: 'S'
-          - AttributeName: executeTime
-            AttributeType: 'N'
         ProvisionedThroughput:
           ReadCapacityUnits:
             Ref: ReadCapacityUnits
diff --git a/src/ingest.js b/src/ingest.js
index b66b9fb..1e589d7 100644
--- a/src/ingest.js
+++ b/src/ingest.js
@@ -8,16 +8,14 @@ module.exports.handler = async (event) => {
       await documentClient.update({
         TableName: process.env.TASKS_TABLE,
         Key: { taskId },
-        UpdateExpression: 'SET #executeTime = :executeTime, #taskId = :taskId, #topicArn = :topicArn, #payload = :payload',
+        UpdateExpression: 'SET #executeTime = :executeTime, #topicArn = :topicArn, #payload = :payload',
         ExpressionAttributeNames: {
           '#executeTime': 'executeTime',
-          '#taskId': 'taskId',
           '#topicArn': 'topicArn',
           '#payload': 'payload'
         },
         ExpressionAttributeValues: {
           ':executeTime': executeTime,
-          ':taskId': taskId,
           ':topicArn': topicArn,
           ':payload': payload
         }
diff --git a/src/schedule.js b/src/schedule.js
index 610daab..322bfc7 100644
--- a/src/schedule.js
+++ b/src/schedule.js
@@ -3,15 +3,13 @@ const AWS = require('aws-sdk')
 module.exports.handler = async () => {
   const sns = new AWS.SNS()
   const documentClient = new AWS.DynamoDB.DocumentClient()
-  const { Items } = await documentClient.query({
+  const { Items } = await documentClient.scan({
     TableName: process.env.TASKS_TABLE,
-    KeyConditionExpression: '#taskId != :taskId AND #executeTime <= :executeTime',
+    FilterExpression: '#executeTime <= :executeTime',
     ExpressionAttributeNames: {
-      '#taskId': 'taskId',
       '#executeTime': 'executeTime'
     },
     ExpressionAttributeValues: {
-      ':taskId': '',
       ':executeTime': (new Date()).getTime() / 1000
     }
   }).promise()
diff --git a/test/ingest.test.js b/test/ingest.test.js
index 03af554..b13ba7a 100644
--- a/test/ingest.test.js
+++ b/test/ingest.test.js
@@ -39,16 +39,14 @@ describe('ingest handler', () => {
     expect(updateStub.mock.calls[0][0]).toEqual({
       TableName: 'tasks-table',
       Key: { taskId: 'test-task-id' },
-      UpdateExpression: 'SET #executeTime = :executeTime, #taskId = :taskId, #topicArn = :topicArn, #payload = :payload',
+      UpdateExpression: 'SET #executeTime = :executeTime, #topicArn = :topicArn, #payload = :payload',
       ExpressionAttributeNames: {
         '#executeTime': 'executeTime',
-        '#taskId': 'taskId',
         '#topicArn': 'topicArn',
         '#payload': 'payload'
       },
       ExpressionAttributeValues: {
         ':executeTime': 20,
-        ':taskId': 'test-task-id',
         ':topicArn': 'arn:aws:sns:us-east-1:123456789:test-topic',
         ':payload': { foo: 'bar' }
       }
diff --git a/test/schedule.test.js b/test/schedule.test.js
index 4cbcd85..80545fb 100644
--- a/test/schedule.test.js
+++ b/test/schedule.test.js
@@ -12,7 +12,7 @@ afterEach(() => {
 })
 
 describe('schedule handler', () => {
-  let publishStub, queryStub, deleteStub
+  let publishStub, scanStub, deleteStub
   beforeEach(() => {
     process.env.TASKS_TABLE = 'tasks-table'
     publishStub = jest.fn((params, callback) => callback(null, 'Success'))
@@ -22,7 +22,7 @@ describe('schedule handler', () => {
   })
   describe('when there are tasks in the past that need to be executed', () => {
     beforeEach(() => {
-      queryStub = jest.fn((params, callback) => callback(null, {
+      scanStub = jest.fn((params, callback) => callback(null, {
         Items: [
           {
             taskId: 'test-task-one',
@@ -36,20 +36,18 @@ describe('schedule handler', () => {
           }
         ]
       }))
-      AWS.mock('DynamoDB.DocumentClient', 'query', queryStub)
+      AWS.mock('DynamoDB.DocumentClient', 'scan', scanStub)
       return handler()
     })
-    it('queries for the items properly', () => {
-      expect(queryStub.mock.calls.length).toEqual(1)
-      expect(queryStub.mock.calls[0][0]).toEqual({
+    it('scans for the items properly', () => {
+      expect(scanStub.mock.calls.length).toEqual(1)
+      expect(scanStub.mock.calls[0][0]).toEqual({
         TableName: 'tasks-table',
-        KeyConditionExpression: '#taskId != :taskId AND #executeTime <= :executeTime',
+        FilterExpression: '#executeTime <= :executeTime',
         ExpressionAttributeNames: {
-          '#taskId': 'taskId',
           '#executeTime': 'executeTime'
         },
         ExpressionAttributeValues: {
-          ':taskId': '',
           ':executeTime': 20
         }
       })
@@ -79,10 +77,10 @@ describe('schedule handler', () => {
   })
   describe('when there are no tasks in the past that need to be executed', () => {
     beforeEach(() => {
-      queryStub = jest.fn((params, callback) => callback(null, {
+      scanStub = jest.fn((params, callback) => callback(null, {
         Items: []
       }))
-      AWS.mock('DynamoDB.DocumentClient', 'query', queryStub)
+      AWS.mock('DynamoDB.DocumentClient', 'scan', scanStub)
       return handler()
     })
     it('does nothing', () => {