Study Notes dlt Fundamentals Course: Lesson 3 & 4 - Pagination, Authentication, dlt Configuration, Sources & Destinations

Lesson 3 Pagination & Authentication & dlt Configuration

Introduction to Pagination

• Pagination is a technique used to retrieve data in pages, especially when an endpoint limits the amount of data that can be fetched at once.
• The GitHub API returns data in pages, and pagination allows us to retrieve all the data.

GitHub API Pagination

• The GitHub API provides the per_page and page query parameters to control pagination.
• The Link header in the response contains URLs for fetching additional pages of data.

Implementing Pagination with dlt's RESTClient

• dlt's RESTClient can handle pagination seamlessly when working with REST APIs like GitHub.
• The RESTClient is part of dlt's helpers, which makes it easier to interact with REST APIs by managing repetitive tasks.

Authentication with GitHub API

• Authentication is required to avoid rate limit errors when fetching data from the GitHub API.
• To authenticate, create an environment variable for your access token or use dlt's secrets configuration.

dlt Configuration and Secrets

• Configurations are non-sensitive settings that define the behavior of a data pipeline.
• Secrets are sensitive data like passwords, API keys, and private keys, which should be kept secure.
• dlt automatically extracts configuration settings and secrets based on flexible naming conventions.

Exercise 1: Pagination with RESTClient

• Use dlt's RESTClient to fetch paginated data from the GitHub API.
• The full list of available paginators can be found in the official dlt documentation.

Exercise 2: Run pipeline with dlt.secrets.value

• Use the sql_client to query the stargazers table and find the user with id 17202864.
• Use environment variables to set the ACCESS_TOKEN variable.

Key Takeaways

• Pagination is essential when working with APIs that return data in pages.
• dlt's RESTClient can handle pagination seamlessly and manage repetitive tasks.
• Authentication is required to avoid rate limit errors when fetching data from the GitHub API.
• dlt configuration and secrets are essential for setting up data pipelines securely.

Further Reading

• GitHub API documentation: Pagination
• dlt documentation: RESTClient, Configuration and Secrets

Lesson 4 Using Pre-built Sources and Destinations

Pre-built Sources

Overview

Pre-built sources are the simplest way to get started with building your stack. They are fully customizable and come with a set of pre-defined configurations.

Types of Pre-built Sources

• Existing Verified Sources: Use an existing verified source by running the dlt init command.
• SQL Databases: Load data from SQL databases (PostgreSQL, MySQL, SQLight, Oracle, IBM DB2, etc.) into a destination.
• Filesystem: Load data from the filesystem, including CSV, Parquet, and JSONL files.
• REST API: Load data from a REST API using a declarative configuration.

Steps to Use Pre-built Sources

1. Install dlt: Install dlt using the dlt init command.
2. List all verified sources: Use the dlt init command to list all available verified sources and their short descriptions.
3. Initialize the source: Initialize the source using the dlt init command.
4. Add credentials: Add credentials using environment variables or other methods.
5. Run the pipeline: Run the pipeline to load data into the destination.

Pre-built Destinations

Overview

Pre-built destinations are used to load data into a specific location. They are customizable and come with a set of pre-defined configurations.

Types of Pre-built Destinations

• Filesystem destination: Load data into files stored locally or in cloud storage solutions.
• Delta tables: Write Delta tables using the deltalake library.
• Iceberg tables: Write Iceberg tables using the pyiceberg library.

Steps to Use Pre-built Destinations

1. Choose a destination: Choose a destination based on your needs.
2. Modify the destination parameter: Modify the destination parameter in your pipeline configuration.
3. Run the pipeline: Run the pipeline to load data into the destination.

Example Use Cases

• Loading data from a SQL database: Use the sql_database source to load data from a SQL database into a destination.
• Loading data from a REST API: Use the rest_api source to load data from a REST API into a destination.
• Loading data from the filesystem: Use the filesystem source to load data from the filesystem into a destination.

Exercise

• Run the rest_api source: Run the rest_api source to load data from a REST API into a destination.
• Run the sql_database source: Run the sql_database source to load data from a SQL database into a destination.
• Run the filesystem source: Run the filesystem source to load data from the filesystem into a destination.

Next Steps

• Proceed to the next lesson: Proceed to the next lesson to learn more about custom sources and destinations.
• Explore the dlt documentation: Explore the dlt documentation to learn more about pre-built sources and destinations.