A Common Table Expression (CTE) is a temporary result set derived from a simple query specified in a WITH clause, which immediately precedes a SELECT or INSERT keyword. The CTE is defined only within the execution scope of a single statement. One or more CTEs can be used in a Hive SELECT, INSERT, CREATE TABLE AS SELECT, or CREATE VIEW AS SELECT statement.
Common Table Expressions are added in Hive 0.13.0 with HIVE-1180.
Common Table Expression Syntax
Additional Grammar Rules
- The WITH clause is not supported within SubQuery Blocks
- CTEs are supported in Views, CTAS and INSERT statements.
- Recursive Queries are not supported.
CTE in Select Statements
CTE in Views, CTAS, and Insert Statements
In the second View example, a query's CTE is different from the CTE used when creating the view. The result will contain rows with key = '5' because in the view's query statement the CTE defined in the view definition takes effect.
Also see this JIRA:
- HIVE-1180 Support Common Table Expressions (CTEs) in Hive