Add basic content

src/data/roadmaps/data-engineer/content/ab-testing@5qe0q_llTzzNVudbONMYo.md

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-# A/B Testing
+# A/B Testing
+
+A/B testing is a way to compare two versions of something to see which one works better. You split your audience into two groups, one sees version A, the other sees version B — and then you measure which version gets better results, like more clicks, sales, or sign-ups. This helps you make decisions based on real data instead of guesses.
+
+Visit the following resources to learn more:
+
+- [@article@A software engineer's guide to A/B testing](https://posthog.com/product-engineers/ab-testing-guide-for-engineers)
+- [@video@A/B Testing for Beginners](https://www.youtube.com/watch?v=VpTlNRUcIDo)

src/data/roadmaps/data-engineer/content/amazon-ec2--compute@AHLsBfPfBJOhLlJ-64GcK.md

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-# Amazon EC2 ( Compute)
+# Amazon EC2 ( Compute)
+
+Amazon Elastic Compute Cloud (EC2) is a web service that provides secure, resizable compute capacity in the cloud. It is designed to make web-scale cloud computing easier for developers. EC2’s simple web service interface allows you to obtain and configure capacity with minimal friction. EC2 enables you to scale your compute capacity, develop and deploy applications faster, and run applications on AWS's reliable computing environment. You have the control of your computing resources and can access various configurations of CPU, Memory, Storage, and Networking capacity for your instances.
+
+Visit the following resources to learn more:
+
+- [@official@EC2 - User Guide](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/concepts.html)
+- [@video@Introduction to Amazon EC2](https://www.youtube.com/watch?v=eaicwmnSdCs)

src/data/roadmaps/data-engineer/content/amazon-rds-database@GtFk7phYGfXUhxanicYNQ.md

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-# Amazon RDS (Database)
+# Amazon RDS (Database)
+
+Amazon RDS (Relational Database Service) is a web service from Amazon Web Services. It's designed to simplify the setup, operation, and scaling of relational databases in the cloud. This service provides cost-efficient, resizable capacity for an industry-standard relational database and manages common database administration tasks. RDS supports six database engines: Amazon Aurora, PostgreSQL, MySQL, MariaDB, Oracle Database, and SQL Server. These engines give you the ability to run instances ranging from 5GB to 6TB of memory, accommodating your specific use case. It also ensures the database is up-to-date with the latest patches, automatically backs up your data and offers encryption at rest and in transit.
+
+Visit the following resources to learn more:
+
+- [@official@Amazon RDS](https://aws.amazon.com/rds/)

src/data/roadmaps/data-engineer/content/amazon-rds-database@nD36-PXHzOXePM7j9u_O_.md

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-# Amazon RDS (Database)
+# Amazon RDS (Database)
+
+Amazon RDS (Relational Database Service) is a web service from Amazon Web Services. It's designed to simplify the setup, operation, and scaling of relational databases in the cloud. This service provides cost-efficient, resizable capacity for an industry-standard relational database and manages common database administration tasks. RDS supports six database engines: Amazon Aurora, PostgreSQL, MySQL, MariaDB, Oracle Database, and SQL Server. These engines give you the ability to run instances ranging from 5GB to 6TB of memory, accommodating your specific use case. It also ensures the database is up-to-date with the latest patches, automatically backs up your data and offers encryption at rest and in transit.
+
+Visit the following resources to learn more:
+
+- [@official@Amazon RDS](https://aws.amazon.com/rds/)

src/data/roadmaps/data-engineer/content/amazon-redshift@omrg8QcYmTdQLBKV47b7o.md

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-# Amazon Redshift
+# Amazon Redshift
+
+Amazon Redshift is a cloud-based data warehouse service from Amazon that lets you store and analyze large amounts of data quickly. It’s designed for running complex queries on huge datasets, so businesses can use it to turn raw data into useful reports and insights. You can load data into Redshift from many sources, and then use SQL to explore it, just like you would with a regular database — but it’s optimized to handle much bigger data and run faster.
+
+Visit the following resources to learn more:
+
+- [@official@Amazon Redshift](https://aws.amazon.com/redshift/)
+- [@video@Getting Started with Amazon Redshift - AWS Online Tech Talks](https://www.youtube.com/watch?v=dfo4J5ZhlKI)

src/data/roadmaps/data-engineer/content/apache-airflow@vfO5Dz6ppsNtbGiQwpUs7.md

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-# Apache Airflow
+# Apache Airflow
+
+Apache Airflow is an open-source tool that helps you schedule, organize, and monitor workflows. Think of it like a to-do list for your data tasks, but smarter — you can set tasks to run in a specific order, track their progress, and see what happens if something fails. It’s often used for automating data pipelines so that data moves, gets processed, and is ready for use without manual work.
+
+Visit the following resources to learn more:
+
+- [@official@Apache Airflow](https://airflow.apache.org/)