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Tera-Tom Genius Series - Hadoop Architecture and SQL by Jason Nolander, Tom Coffing

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Chapter 17 – Hadoop EXPLAIN

“Lucy, you got some ‘splainin’ to do!”

- Ricky Ricardo

There are Many Options to See an EXPLAIN Plan

Syntax: EXPLAIN [EXTENDED|DEPENDENCY|AUTHORIZATION] query

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To get an EXPLAIN, you can either type the word EXPLAIN in front of any Hadoop SQL or click on the magnifying glass of Nexus. Hive provides an EXPLAIN command designed to show the user the execution plan for a query being explained. The EXPLAIN plan is designed to show the user exactly how Hive translates queries into MapReduce jobs.

Explain Output has Three Parts

An Abstract Syntax Tree is really the internalsource code that is represented as a tree of nodes. ...

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