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June 17, 2012

Columnar Database Query Execution Basics

This post is to learn answer for How Query execution works in a Columnar database.

Row based storage - This is B-Tree based storage. If we have defined Clustered index on the table, Data would be ordered in based on the Clustered index key. There are a bunch of posts in msdn / blogs to explore more on this. Early Materialization happens in case of row based storage.

Coming to Columnar storage, How it works. From link Query execution in columnar database.

For column based Storage
  • Late Materialization (Load all required columns and then perform required join / filters)
  • Invisible join is another interesting concept
This link  was very useful about columnar databases. Below slide from tutorial is very good on fetching required columns and apply required filters for column store.

Happy Learning!!!

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