How to load data from SendGrid to PostgreSQL

Extract data from SendGrid

There are two main methods to get our data from SendGrid, the first one is to pull data out from it and the second one is for SendGrid to push data to you whenever an important event is triggered. The second solution is also offering a real-time aspect to the analytics we can perform with SendGrid. We will see how we can access data from both.

In order to pull data from SendGrid, we need to access its HTTP API. As a Web API following the RESTful architecture principles, it can be accessed through HTTP.

As a RESTful API, interacting with it can be achieved by using tools like CURL or Postman or by using http clients for your favorite language or framework. A few suggestions:

  • Apache HttpClient for Java
  • Spray-client for Scala
  • Hyper for Rust
  • Ruby rest-client
  • Python http-client

SendGrid maintains a number of officially supported clients or SDKs that you can use with your favorite language to access it without having to mess with the raw underlying HTTP calls. These are the following:

There’s also a huge list of community-supported libraries that you can use if you wish. A complete list can be found here.

SendGrid is currently maintaining 4 APIs that can be accessed.

  • SMTP API. SendGrid’s SMTP API allows developers to specify custom handling instructions for e-mail.
  • Web API v3. The latest version of the SendGridAPI is completely RESTful, fully featured, and easy to integrate.
  • Web API v2. The previous version of the SendGridAPI is still maintained for compatibility reasons. It is recommended that v3 is used instead of it as soon as possible.
  • Webhooks. Webhooks are an easy way to get push notifications from SendGrid.

For this guide, we are considering the v3 of the Web API and Webhooks.

SendGrid API Authentication

Authentication for accessing the SendGrid Web API happens through API keys. You generate an API Key that then you can pass together with your requests to the API, and your application will be authenticated. Additionally to the creation of API Keys, SendGrid also allows the creation and management of API Key permission lists.

So you can create Keys that will have different levels of access to SendGrid for your account. API requests you make to the Web API v3 must be authenticated by including an Authorization Header with your API Key.

SendGrid rate limiting

There are limitations to delivery rates imposed by recipient mail servers. Exceeding these limitations results in a practice referred to as throttling. Throttling in terms of email means that a recipient mail server has accepted all the mail it is willing to accept from your IP for a certain period of time.

Apart from throttling that can occur depending on the recipients’ server, SendGrid is also limiting the number of emails that you can send on a per-month period, based on the plan that you have purchased. For more information about this, you should consult the pricing page of SendGrid.

Endpoints and available resources

Some of the most important endpoints that SendGrid exposes are the following. You can also find the complete list of endpoints the Web API v3 exposes here:

  • Operations related to your users.
  • Marketing Campaigns. Campaign-related operations about loading in contacts, create segments, create and send campaigns, view your stats, and much more.
  • Operations related to white label lists of domains and subdomains, IPs, and URLs.
  • SendGrid email statistics.
  • Spam reports. Operations related to spam reports that SendGrid generates for your emails and campaigns.

And much more can be found on the link given above.

Not all of the provided endpoints are useful for pulling out data that can be used for analytics. The most important for this job are the Stats and report endpoints that SendGrid exposes. As an example, let’s assume that we want to fetch data from the Global Stats endpoint. To do that we need to perform a GET request to the following URL, providing a valid API key:

JAVASCRIPT
GET https://api.sendgrid.com/v3/stats?start_date=2015-01-01&end_date=2015-01-02 HTTP/1.1

If you pay attention to the above URL, you will notice that we are also providing two parameters, the start and end dates for which we would like to fetch statistics. The response will be in JSON format and will look like the following:

JAVASCRIPT
HTTP/1.1 200
[
 {
   "date": "2015-01-01",
   "stats": [
     {
       "metrics": {
         "blocks": 1,
         "bounce_drops": 0,
         "bounces": 0,
         "clicks": 0,
         "deferred": 1,
         "delivered": 1,
         "invalid_emails": 1,
         "opens": 1,
         "processed": 2,
         "requests": 3,
         "spam_report_drops": 0,
         "spam_reports": 0,
         "unique_clicks": 0,
         "unique_opens": 1,
         "unsubscribe_drops": 0,
         "unsubscribes": 0
       }
     }
   ]
 },
]

Statistics consist of the following metrics:

And there are a number of sub-endpoints that you can access for more specific metrics and statistics. These are the following:

Another way of retrieving metrics and statistics from the SendGrid API is by requesting it to push data to our system every time a new event occurs. To do that we need to use the Webhooks API which sends events to a predefined URL using POST requests. Events that are sent by the SendGrid API have a structure like the following:

JAVASCRIPT
[
 {
   "sg_message_id":"sendgrid_internal_message_id",
   "email": "john.doe@sendgrid.com",
   "timestamp": 1337197600,
   "smtp-id": "<4FB4041F.6080505@sendgrid.com>",
   "event": "processed"
 },
 {
   "sg_message_id":"sendgrid_internal_message_id",
   "email": "john.doe@sendgrid.com",
   "timestamp": 1337966815,
   "category": "newuser",
   "event": "click",
   "url": "https://sendgrid.com"
 },
 {
   "sg_message_id":"sendgrid_internal_message_id",
   "email": "john.doe@sendgrid.com",
   "timestamp": 1337969592,
   "smtp-id": "<20120525181309.C1A9B40405B3@Example-Mac.local>",
   "event": "group_unsubscribe",
   "asm_group_id": 42
 }
]

These events can be stored in your data warehouse solution like PostgreSQL for analysis or they can be used to trigger specific actions as they arrive.

Prepare your SendGrid data for PostgreSQL

To populate a PostgreSQL database instance with data, first, you need to have a well-defined data model or schema that describes the data. As a relational database, PostgreSQL organizes data around tables.

Each table is a collection of columns with a predefined data type like an integer or VARCHAR. PostgreSQL, like any other SQL database, supports a wide range of different data types.

A typical strategy for loading data from SendGrid to a PostgreSQL database is to create a schema where you will map each API endpoint to a table. Each key inside the SendGrid API endpoint response should be mapped to a column of that table and you should ensure the right conversion to a PostgreSQL compatible data type.

For example, if an endpoint from SendGrid returns a value as String, you should convert it into a VARCHAR with a predefined max size or TEXT data type. tables can then be created on your database using the CREATE SQL statement.

Of course, you will need to ensure that as the data types from the SendGrid API might change, you will adapt your database tables accordingly, there’s no such thing as automatic data type casting.

After you have a complete and well-defined data model or schema for PostgreSQL, you can move forward and start loading your data into the database.

Load data from SendGrid to PostgreSQL

Once you have defined your schema and you have created your tables with the proper data types, you can start loading data into your database.

The most straightforward way to insert data into a PostgreSQL database is by creating and executing INSERT statements. With INSERT statements, you will be adding data row-by-row directly to a table. It is the most basic and straightforward way of adding data into a table but it doesn’t scale very well with larger data sets.

The preferred way for adding larger datasets into a PostgreSQL database is by using the COPY command. COPY is copying data from a file on a file system that is accessible by the PostgreSQL instance, in this way much larger datasets can be inserted into the database in less time.

You should also consult the documentation of PostgreSQL on how to populate a database with data. It includes a number of very useful best practices on how to optimize the process of loading data into your PostgreSQL database.

COPY requires physical access to a file system in order to load data. Nowadays, with cloud-based, fully managed databases, getting direct access to a file system is not always possible. If this is the case and you cannot use a COPY statement, then another option is to use PREPARE together with INSERT, to end up with optimized and more performant INSERT queries.

Updating your SendGrid data on Postgres

As you will be generating more data on SendGrid, you will need to update your older data on Postgres. This includes new records together with updates to older records that for any reason have been updated on SendGrid.

You will need to periodically check SendGrid for new data and repeat the process that has been described previously while updating your currently available data if needed. Updating an already existing row on a Postgres table is achieved by creating UPDATE statements.

Another issue that you need to take care of is the identification and removal of any duplicate records on your database. Either because SendGrid does not have a mechanism to identify new and updated records or because of errors on your data pipelines, duplicate records might be introduced to your database.

In general, ensuring the quality of the data that is inserted in your database is a big and difficult issue and PostgreSQL features like TRANSACTIONS can help tremendously, although they do not solve the problem in the general case.

The best way of loading data from SendGrid to PostgreSQL

So far we just scraped the surface of what you can do with PostgreSQL and how you can load data into it. Things can get even more complicated if you want to integrate data coming from different sources.

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