Advanced dbt use cases with Teradata Vantage

Overview

This project showcases the integration of dbt with Teradata Vantage from an advanced user perspective. If you are new to data engineering with dbt we recommend that you start with our introductory project.

The advanced use cases showcased in the demo are the following:

• Incremental materializations
• Utility macros
• Optimizing table/view creations with Teradata-specific modifiers

The application of these concepts is illustrated through the ELT process of teddy_retailers, a fictional store.

Prerequisites

• Access to a Teradata Vantage instance.

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  If you need a test instance of Vantage, you can provision one for free at https://clearscape.teradata.com

• Python 3.7, 3.8, 3.9 or 3.10 installed.

• A database client for running database commands, an example of the configuration of one such client is presented in this tutorial..

Demo project setup

1. Clone the tutorial repository and cd into the project directory:

2. Create a new python environment to manage dbt and its dependencies. Confirm that the Python Version you are using to create the environment is within the supported versions listed above.

3. Activate the python environment according to your operating system.

   for Mac, Linux, or

   for Windows

4. Install the dbt-teradata module. The core dbt module is included as a dependency so you don't have to install it separately:

5. Install the project's dependencies dbt-utils and teradata-utils. This can be done through the following command:

Data warehouse setup

The demo project assumes that the source data is already loaded into your data warehouse, this mimics the way that dbt is used in a production environment. To achieve this objective we provide public datasets available in Google Cload Platform (GCP), and scripts to load those datasets into your mock data warehouse.

1. Create or select a working database. The dbt profile in the project points to a database called teddy_retailers. You can change the schema value to point to an existing database in your Teradata Vantage instance or you can create the teddy_retailers database running the following script in your database client:
2. Load Initial data set. To load the initial data set into the data warehouse, the required scripts are available in the references/inserts/create_data.sql path of the project. You can execute these scripts by copying and pasting them into your database client. For guidance on running these scripts in your specific case please consult your database client's documentation.

Configure dbt

We will now configure dbt to connect to your Vantage database. Create the file $HOME/.dbt/profiles.yml with the following content. Adjust <host>, <user>, <password> to match your Teradata Vantage instance. If you have already used dbt before in your environment you only need to add a profile for the project in your home's directory .dbt/profiles.yml file. If the directory .dbt doesn't exist in your system yet you will need to create it and add the profiles.yml to manage your dbt profiles.

Now, that we have the profile file in place, we can validate the setup:

If the debug command returned errors, you likely have an issue with the content of profiles.yml.

About the Teddy Retailers warehouse

As mentioned, teddy_retailers is a fictional store. Through dbt driven transformations we transform source data ingested from theteddy_retailers transactional database into a star schema ready for analytics.

The data models

The source data consists of the following tables customers, orders, products, and order_products, according to the following Entity Relations Diagram:

Using dbt, we leverage the source data tables to construct the following dimensional model, which is optimized for analytics tools.

The sources

• For Teddy Retailers, the orders and order_products sources are periodically updated by the organization's ELT (Extract, Load, Transform) process.
• The updated data only includes the latest changes rather than the entire dataset due to its large volume.
• To address this challenge, it is necessary to capture these incremental updates while preserving the previously available data.

The dbt models

The schema.yml file in the project's models directory specifies the sources for our models. These sources align with the data we loaded from GCP using our SQL scripts.

Staging area

The staging area models are merely ingesting the data from each of the sources and renaming each field, if appropiate. In the schema.yml of this directory we define basic integrity checks for the primary keys.

Core area

The following advanced dbt concepts are applied in the models at this stage:

Incremental materializations

The schema.yml file in this directory specifies that the materializations of the two models we are building are incremental. We employ different strategies for these models:

• For the all_orders model, we utilize the delete+insert strategy. This strategy is implemented because there may be changes in the status of an order that are included in the data updates.
• For the all_order_products model, we employ the default append strategy. This approach is chosen because the same combination of order_id and product_id may appear multiple times in the sources. This indicates that a new quantity of the same product has been added or removed from a specific order.

Macro assisted assertions

Within the all_order_products model, we have included an assertion with the help of a macro to test and guarantee that the resulting model encompasses a unique combination of order_id and product_id. This combination denotes the latest quantity of products of a specific type per order.

Teradata modifiers

For both the all_order and all_order_products models, we have incorporated Teradata Modifiers to enhance tracking of these two core models. To facilitate collecting statistics, we have added a post_hook that instructs the database connector accordingly. Additionally, we have created an index on the order_id column within the all_orders table.

Running transformations

Create dimensional model with baseline data

By executing dbt, we generate the dimensional model using the baseline data.

This will create both our core and dimensional models using the baseline data.

Test the data

We can run our defined test by executing:

Running sample queries

You can find sample business intelligence queries in the references/query path of the project. These queries allow you to analyze the factual data based on dimensions such as customers, orders, and products.

Mocking the ELT process

The scripts for loading updates into the source data set can be found in the references/inserts/update_data.sql path of the project.

After updating the data sources, you can proceed with the aforementioned steps: running dbt, testing the data, and executing sample queries. This will allow you to visualize the variations and incremental updates in the data.

Summary

In this tutorial, we explored the utilization of advanced dbt concepts with Teradata Vantage. The sample project showcased the transformation of source data into a dimensional data mart. Throughout the project, we implemented several advanced dbt concepts, including incremental materializations, utility macros, and Teradata modifiers.

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