A columnar database is optimized for fast retrieval of columns of data, typically in analytical applications. Column-oriented storage for database tables is an important factor in analytic query performance because it drastically reduces the overall disk I/O requirements, and reduces the amount of data you need to load from disk.
Like other NoSQL databases, column-oriented databases are designed to scale “out” using distributed clusters of low-cost hardware to increase throughput, making them ideal for data warehousing and Big Data processing.
What's is data transformation? Why do we keep talking about SQL? Here's a list of terms to help you learn the language of Matillion and ETL.