There are a few key limitations in Hive that prevent some regular Metadata Editor features from working as intended, and limit the structure of your SQL queries in Report Designer:
- Outer joins are not supported.
- Each column can only be used once in a SELECT clause. Duplicate columns in SELECT statements cause errors.
- Conditional joins can only use the = conditional unless you use a WHERE clause. Any non-equal conditional in a FROM statement forces the Metadata Editor to use a cartesian join and a WHERE clause conditional to limit it. This is not much of a limitation, but it may seem unusual to experienced Metadata Editor users who are accustomed to working with SQL databases.