Data Science
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Learn how to analyze data effectively and manage databases with ease.

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πŸ”° 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.


πŸ“‹ 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
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πŸ”… SQL Practice: Intermediate Queries

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

🌐 Author: Scott Simpson
πŸ”° Level: Intermediate
⏰ Duration: 11m

πŸ“‹ Topics: SQL, Database Queries

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SQL Practice: Intermediate Queries.zip
18.7 MB
πŸ“±Data Analysis
πŸ“±SQL Practice: Intermediate Queries
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πŸ“– SQL Joins
πŸ“ Master Excel like a pro

Here's your ultimate Excel Cheat Sheet tailored for Data Analysts. Save it, share it, and boost your productivity!
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Here’s a practical, code-first playbook for exploring numerical data πŸ‘‡

How we approach EDA (with Python code + outputs):

- Basics: shape, dtypes, and missing values.
- Descriptives: mean/median, variance, and percentiles for quick sanity checks.
- Distributions: histograms, boxplots, density to spot skew and spread.
- Relationships: scatter plots and a correlation heatmap to find signals.
- Outliers: z-scores/IQR to flag anomalies worth investigating.
- Scaling: MinMax vs Z-score depending on the model and metric.
- Segments: groupby comparisons to surface patterns you miss in globals.
- Decisions: tie insights back to the question and next steps.

What this really means is: you get a repeatable workflow that turns raw numbers into clear hypotheses fast.
πŸ”… Learning Apache Airflow

πŸ“ Get an introduction to Apache Airflowβ€”its uses, structure, how to get it up and running, and how to create and execute workflows.

🌐 Author: Janani Ravi
πŸ”° Level: Advanced
⏰ Duration: 2h 10m

πŸ“‹ Topics: Apache Airflow, IT Automation

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Learning Apache Airflow.zip
271.3 MB
πŸ“±Data Analysis
πŸ“±Learning Apache Airflow
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πŸ“– Data Visualization CheatSheet
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πŸ“– Data Science
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πŸ“– Data Analytic Skills that will get you hired
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