📖 SQL Commands

🔰 PostgreSQL 101: The Everything Database

Built using C language, PostgreSQL is the most popular choice of database from small web apps to enterprise systems. It runs as a multi-process system and follows ACID principles.

📋 The key points about PostgreSQL’s Architecture are as follows:

1 - PostgreSQL supports concurrent client connections independently. Each client connection to PostgreSQL creates a dedicated server process.

2 - The Postmaster Process is the main supervisor that manages all other PostgreSQL processes. It controls the entire database instance.

3 - Background workers run parallel processes when needed to handle specialized tasks.

4 - PostgreSQL shared memory is a central memory area containing multiple buffers such as Shared, WAL, Clog, and Temporary buffers. All components communicate through this shared memory.

5 - PostgreSQL also has several auxiliary processes such as:
- BG Writer: Manages background writing
- WAL Writer: Handles write-ahead logging
- Auto Vacuum: Maintains database cleanliness
- Checkpointer: Ensures data consistency
- Stats Collector: Gathers statistics
- System Logger: Manages Logging
- Archiver: Handles archiving
- Replication launcher: Manages replication

6 - PostgreSQL has different types of physical files for varied needs such as:
- Data Files: Stores actual database data
- WAL Files: Write-ahead log storage
- Archive Files: Backup and recovery data
- Log Files: System and error logs

🔅 SQL Practice: Intermediate Queries

📝 Practice writing immediate queries in SQL in this hands-on, interactive course with coding challenges in CoderPad.

🌐 Author: Scott Simpson
🔰 Level: Intermediate
⏰ Duration: 11m

📋 Topics: SQL, Database Queries

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📱Data Analysis
📱SQL Practice: Intermediate Queries

📁 Master Excel like a pro

Here's your ultimate Excel Cheat Sheet tailored for Data Analysts. Save it, share it, and boost your productivity!

🔅 Learning Apache Airflow

📝 Get an introduction to Apache Airflow—its uses, structure, how to get it up and running, and how to create and execute workflows.

🌐 Author: Janani Ravi
🔰 Level: Advanced
⏰ Duration: 2h 10m

📋 Topics: Apache Airflow, IT Automation

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📱Data Analysis
📱Learning Apache Airflow

📦 Exercise Files