Posts Tagged IoT
Databases are ideal for storing and organizing data that requires a high volume of transaction-oriented query processing while maintaining data integrity. In contrast, data warehouses are designed for performing data analytics on vast amounts of data from one or more disparate sources. In our fast-paced, hyper-connected world, those sources often take the form of continuous streams of web application logs, e-commerce transactions, social media feeds, online gaming activities, financial trading transactions, and IoT sensor readings. Streaming data must be analyzed in near real-time, while often first requiring cleansing, transformation, and enrichment.
In the following post, we will demonstrate the use of Amazon Kinesis Data Firehose, Amazon Redshift, and Amazon QuickSight to analyze streaming data. We will simulate time-series data, streaming from a set of IoT sensors to Kinesis Data Firehose. Kinesis Data Firehose will write the IoT data to an Amazon S3 Data Lake, where it will then be copied to Redshift in near real-time. In Amazon Redshift, we will enhance the streaming sensor data with data contained in the Redshift data warehouse, which has been gathered and denormalized into a star schema.
In Redshift, we can analyze the data, asking questions like, what is the min, max, mean, and median temperature over a given time period at each sensor location. Finally, we will use Amazon Quicksight to visualize the Redshift data using rich interactive charts and graphs, including displaying geospatial sensor data.
The following AWS services are discussed in this post.
Amazon Kinesis Data Firehose
According to Amazon, Amazon Kinesis Data Firehose can capture, transform, and load streaming data into data lakes, data stores, and analytics tools. Direct Kinesis Data Firehose integrations include Amazon S3, Amazon Redshift, Amazon Elasticsearch Service, and Splunk. Kinesis Data Firehose enables near real-time analytics with existing business intelligence (BI) tools and dashboards.
According to Amazon, Amazon Redshift is the most popular and fastest cloud data warehouse. With Redshift, users can query petabytes of structured and semi-structured data across your data warehouse and data lake using standard SQL. Redshift allows users to query and export data to and from data lakes. Redshift can federate queries of live data from Redshift, as well as across one or more relational databases.
Amazon Redshift Spectrum
According to Amazon, Amazon Redshift Spectrum can efficiently query and retrieve structured and semistructured data from files in Amazon S3 without having to load the data into Amazon Redshift tables. Redshift Spectrum tables are created by defining the structure for data files and registering them as tables in an external data catalog. The external data catalog can be AWS Glue or an Apache Hive metastore. While Redshift Spectrum is an alternative to copying the data into Redshift for analysis, we will not be using Redshift Spectrum in this post.
According to Amazon, Amazon QuickSight is a fully managed business intelligence service that makes it easy to deliver insights to everyone in an organization. QuickSight lets users easily create and publish rich, interactive dashboards that include Amazon QuickSight ML Insights. Dashboards can then be accessed from any device and embedded into applications, portals, and websites.
What is a Data Warehouse?
According to Amazon, a data warehouse is a central repository of information that can be analyzed to make better-informed decisions. Data flows into a data warehouse from transactional systems, relational databases, and other sources, typically on a regular cadence. Business analysts, data scientists, and decision-makers access the data through business intelligence tools, SQL clients, and other analytics applications.
All the source code for this post can be found on GitHub. Use the following command to git clone a local copy of the project.
Use the two AWS CloudFormation templates, included in the project, to build two CloudFormation stacks. Please review the two templates and understand the costs of the resources before continuing.
The first CloudFormation template, redshift.yml, provisions a new Amazon VPC with associated network and security resources, a single-node Redshift cluster, and two S3 buckets.
The second CloudFormation template, kinesis-firehose.yml, provisions an Amazon Kinesis Data Firehose delivery stream, associated IAM Policy and Role, and an Amazon CloudWatch log group and two log streams.
REDSHIFT_PASSWORD value to ensure your security. Optionally, change the
REDSHIFT_USERNAME value. Make sure that the first stack completes successfully, before creating the second stack.
Review AWS Resources
To confirm all the AWS resources were created correctly, use the AWS Management Console.
Kinesis Data Firehose
In the Amazon Kinesis Dashboard, you should see the new Amazon Kinesis Data Firehose delivery stream, redshift-delivery-stream.
The Details tab of the new Amazon Kinesis Firehose delivery stream should look similar to the following. Note the IAM Role, FirehoseDeliveryRole, which was created and associated with the delivery stream by CloudFormation.
We are not performing any transformations of the incoming messages. Note the new S3 bucket that was created and associated with the stream by CloudFormation. The bucket name was randomly generated. This bucket is where the incoming messages will be written.
Note the buffer conditions of 1 MB and 60 seconds. Whenever the buffer of incoming messages is greater than 1 MB or the time exceeds 60 seconds, the messages are written in JSON format, using GZIP compression, to S3. These are the minimal buffer conditions, and as close to real-time streaming to Redshift as we can get.
COPY command, which is used to copy the messages from S3 to the
message table in Amazon Redshift. Kinesis uses the IAM Role, ClusterPermissionsRole, created by CloudFormation, for credentials. We are using a Manifest to copy the data to Redshift from S3. According to Amazon, a Manifest ensures that the
COPY command loads all of the required files, and only the required files, for a data load. The Manifests are automatically generated and managed by the Kinesis Firehose delivery stream.
In the Amazon Redshift Console, you should see a new single-node Redshift cluster consisting of one Redshift dc2.large Dense Compute node type.
Note the new VPC, Subnet, and VPC Security Group created by CloudFormation. Also, observe that the Redshift cluster is publically accessible from outside the new VPC.
Redshift Ingress Rules
The single-node Redshift cluster is assigned to an AWS Availability Zone in the US East (N. Virginia) us-east-1 AWS Region. The cluster is associated with a VPC Security Group. The Security Group contains three inbound rules, all for Redshift port 5439. The IP addresses associated with the three inbound rules provide access to the following: 1) a
/27 CIDR block for Amazon QuickSight in us-east-1, a
/27 CIDR block for Amazon Kinesis Firehose in us-east-1, and to you, a
/32 CIDR block with your current IP address. If your IP address changes or you do not use the us-east-1 Region, you will need to change one or all of these IP addresses. The list of Kinesis Firehose IP addresses is here. The list of QuickSight IP addresses is here.
If you cannot connect to Redshift from your local SQL client, most often, your IP address has changed and is incorrect in the Security Group’s inbound rule.
Redshift SQL Client
You can choose to use the Redshift Query Editor to interact with Redshift or use a third-party SQL client for greater flexibility. To access the Redshift Query Editor, use the user credentials specified in the redshift.yml CloudFormation template.
There is a lot of useful functionality in the Redshift Console and within the Redshift Query Editor. However, a notable limitation of the Redshift Query Editor, in my opinion, is the inability to execute multiple SQL statements at the same time. Whereas, most SQL clients allow multiple SQL queries to be executed at the same time.
I prefer to use JetBrains PyCharm IDE. PyCharm has out-of-the-box integration with RedShift. Using PyCharm, I can edit the project’s Python, SQL, AWS CLI shell, and CloudFormation code, all from within PyCharm.
If you use any of the common SQL clients, you will need to set-up a JDBC (Java Database Connectivity) or ODBC (Open Database Connectivity) connection to Redshift. The ODBC and JDBC connection strings can be found in the Redshift cluster’s Properties tab or in the Outputs tab from the CloudFormation stack,
You will also need the RedShift database username and password you included in the
aws cloudformation create-stack AWS CLI command you executed previously. Below, we see PyCharm’s Project Data Sources window containing a new data source for the Redshift
Database Schema and Tables
When CloudFormation created the Redshift cluster, it also created a new database,
dev. Using the Redshift Query Editor or your SQL client of choice, execute the following series of SQL commands to create a new database schema,
sensor, and six tables in the
The tables represent denormalized data, taken from one or more relational database sources. The tables form a star schema. The star schema is widely used to develop data warehouses. The star schema consists of one or more fact tables referencing any number of dimension tables. The
history tables are dimension tables. The
sensors table is a fact table.
In the diagram below, the foreign key relationships are virtual, not physical. The diagram was created using PyCharm’s schema visualization tool. Note the schema’s star shape. The
message table is where the streaming IoT data will eventually be written. The
message table is related to the
sensors fact table through the common
Sample Data to S3
Next, copy the sample data, included in the project, to the S3 data bucket created with CloudFormation. Each CSV-formatted data file corresponds to one of the tables we previously created. Since the bucket name is semi-random, we can use the AWS CLI and jq to get the bucket name, then use it to perform the copy commands.
The output from the AWS CLI should look similar to the following.
Sample Data to RedShift
Whereas a relational database, such as Amazon RDS is designed for online transaction processing (OLTP), Amazon Redshift is designed for online analytic processing (OLAP) and business intelligence applications. To write data to Redshift we typically use the
COPY command versus frequent, individual
INSERT statements, as with OLTP, which would be prohibitively slow. According to Amazon, the Redshift
COPY command leverages the Amazon Redshift massively parallel processing (MPP) architecture to read and load data in parallel from files on Amazon S3, from a DynamoDB table, or from text output from one or more remote hosts.
In the following series of SQL statements, replace the placeholder,
your_bucket_name, in five places with your S3 data bucket name. The bucket name will start with the prefix,
redshift-stack-databucket. The bucket name can be found in the Outputs tab of the CloudFormation stack,
redshift-stack. Next, replace the placeholder,
cluster_permissions_role_arn, with the ARN (Amazon Resource Name) of the ClusterPermissionsRole. The ARN is formatted as follows,
arn:aws:iam::your-account-id:role/ClusterPermissionsRole. The ARN can be found in the Outputs tab of the CloudFormation stack,
Using the Redshift Query Editor or your SQL client of choice, execute the SQL statements to copy the sample data from S3 to each of the corresponding tables in the Redshift
dev database. The
TRUNCATE commands guarantee there is no previous sample data present in the tables.
Next, create four Redshift database Views. These views may be used to analyze the data in Redshift, and later, in Amazon QuickSight.
- sensor_msg_detail: Returns aggregated sensor details, using the
sensorsfact table and all five dimension tables in a SQL Join.
- sensor_msg_count: Returns the number of messages received by Redshift, for each sensor.
- sensor_avg_temp: Returns the average temperature from each sensor, based on all the messages received from each sensor.
- sensor_avg_temp_current: View is identical for the previous view but limited to the last 30 minutes.
Using the Redshift Query Editor or your SQL client of choice, execute the following series of SQL statements.
At this point, you should have a total of six tables and four views in the
sensor schema of the
dev database in Redshift.
Test the System
With all the necessary AWS resources and Redshift database objects created and sample data in the Redshift database, we can test the system. The included Python script, kinesis_put_test_msg.py, will generate a single test message and send it to Kinesis Data Firehose. If everything is working, the message should be delivered from Kinesis Data Firehose to S3, then copied to Redshift, and appear in the
Install the required Python packages and then execute the Python script.
Run the following SQL query to confirm the record is in the
message table of the
dev database. It will take at least one minute for the message to appear in Redshift.
Once the message is confirmed to be present in the
message table, delete the record by truncating the table.
Assuming the test message worked, we can proceed with simulating the streaming IoT sensor data. The included Python script, kinesis_put_streaming_data.py, creates six concurrent threads, representing six temperature sensors. The simulated data uses an algorithm that follows an oscillating sine wave or sinusoid, representing rising and falling temperatures. In the script, I have configured each thread to start with an arbitrary offset to add some randomness to the simulated data.
The variables within the script can be adjusted to shorten or lengthen the time it takes to stream the simulated data. By default, each of the six threads creates 400 messages per sensor, in one-minute increments. Including the offset start of each proceeding thread, the total runtime of the script is about 7.5 hours to generate 2,400 simulated IoT sensor temperature readings and push to Kinesis Data Firehose. Make sure you can guarantee you will maintain a connection to the Internet for the entire runtime of the script. I normally run the script in the background, from a small EC2 instance.
To use the Python script, execute either of the two following commands. Using the first command will run the script in the foreground. Using the second command will run the script in the background.
If you used the foreground command, you should see messages being generated by each thread and sent to Kinesis Data Firehose. Each message contains the GUID of the sensor, a timestamp, and a temperature reading.
The messages are sent to Kinesis Data Firehose, which in turn writes the messages to S3. The messages are written in JSON format using GZIP compression. Below, we see an example of the GZIP compressed JSON files in S3. The JSON files are partitioned by year, month, day, and hour.
Confirm Data Streaming to Redshift
From the Amazon Kinesis Firehose Console Metrics tab, you should see incoming messages flowing to S3 and on to Redshift.
Executing the following SQL query should show an increasing number of messages.
How Near Real-time?
Earlier, we saw how the Amazon Kinesis Data Firehose delivery stream was configured to buffer data at the rate of 1 MB or 60 seconds. Whenever the buffer of incoming messages is greater than 1 MB or the time exceeds 60 seconds, the messages are written to S3. Each record in the
message table has two timestamps. The first timestamp, ts, is when the temperature reading was recorded. The second timestamp, created, is when the message was written to Redshift, using the
COPY command. We can calculate the delta in seconds between the two timestamps using the following SQL query in Redshift.
Using the results of the Redshift query, we can visualize the results in Amazon QuickSight. In my own tests, we see that for 2,400 messages, over approximately 7.5 hours, the minimum delay was 1 second, and a maximum delay was 64 seconds. Hence, near real-time, in this case, is about one minute or less, with an average latency of roughly 30 seconds.
Analyzing the Data with Redshift
I suggest waiting at least thirty minutes for a significant number of messages copied into Redshift. With the data streaming into Redshift, execute each of the database views we created earlier. You should see the streaming message data, joined to the existing static data in RedShift. As data continues to stream into Redshift, the views will display different results based on the current
message table contents.
Here, we see the first ten results of the
Next, we see the results of the
In a recent post, Getting Started with Data Analysis on AWS using AWS Glue, Amazon Athena, and QuickSight: Part 2, I detailed getting started with Amazon QuickSight. In this post, I will assume you are familiar with QuickSight.
Amazon recently added a full set of
aws quicksight APIs for interacting with QuickSight. Though, for this part of the demonstration, we will be working directly in the Amazon QuickSight Console, as opposed to the AWS CLI, AWS CDK, or CloudFormation.
Redshift Data Sets
To visualize the data from Amazon Redshift, we start by creating Data Sets in QuickSight. QuickSight supports a large number of data sources for creating data sets. We will use the Redshift data source. If you recall, we added an inbound rule for QuickSight, allowing us to connect to our Redshift cluster in us-east-1.
We will select the
sensor schema, which is where the tables and views for this demonstration are located.
We can choose any of the tables or views in the Redshift
dev database that we want to use for visualization.
Below, we see examples of two new data sets, shown in the QuickSight Data Prep Console. Note how QuickSight automatically recognizes field types, including dates, latitude, and longitude.
Using the data sets, QuickSight allows us to create a wide number of rich visualizations. Below, we see the simulated time-series data from the six temperature sensors.
Next, we see an example of QuickSight’s ability to show geospatial data. The Map shows the location of each sensor and the average temperature recorded by that sensor.
To remove the resources created for this post, use the following series of AWS CLI commands.
In this brief post, we have learned how streaming data can be analyzed in near real-time, in Amazon Redshift, using Amazon Kinesis Data Firehose. Further, we explored how the results of those analyses can be visualized in Amazon QuickSight. For customers that depend on a data warehouse for data analytics, but who also have streaming data sources, the use of Amazon Kinesis Data Firehose or Amazon Redshift Spectrum is an excellent choice.
This blog represents my own viewpoints and not of my employer, Amazon Web Services.