Etl

README.md

@@ -56,6 +56,10 @@ This repository serves as a collection of things learned by people working in AG
 
 - [Basic SQLite3](sqlite3/basic-sqlite3.md)
 
+### ETL
+
+- [Basic ETL](etl/basic-etl.md)
+
 ## Contributing
 
 If you want to share your learnings for today, please check out CONTRIBUTING.md

etl/basic-etl.md

@@ -0,0 +1,24 @@
+# ETL - Basic
+
+**Date: (June 29, 2016)**
+
+ETL or *Extract - Transform - Load* is a process done in data warehousing. It is used when:
+- You want to aggregate data from different sources into one collection (the warehouse)
+- You want to select and arrange only the pertinent information for any kind of analytic, and provide his/her own user view of the data (Data mart)
+- You want to clean the data and make meaningful sense out of it.
+
+ETL can be broken down to three major steps:
+
+1. Extract
+    - The part where you gather data from different data sources (csv files, databases, etc...). Data can also come from different data warehouses.
+    - It should be designed to avoid negative effects on source system such as its performance, response time, or any kind of data locking.
+
+2. Transform
+    - Making the extracted data usable.
+    - This includes mapping the data, matching rows, enhancing data, summarizing data, etc.
+    - Transformation also includes standardizing data (such as currency and time formats) and handling encoding
+
+3. Load
+    - Fetches prepared data and storing them to the data warehouse and database, or data mart.
+
+Source: [ETL Tutorial | Extract Transform and Load](https://www.youtube.com/watch?v=WZw0OTgCBOY)