[HIVE-591] create new type of join ( 1 row for a given key from multiple tables) (UNIQUEJOIN)

• Type: New Feature
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 0.5.0
• Component/s: Query Processor
• Hadoop Flags: Reviewed
• Assignee: Emil Ibrishimov
• Reporter: Namit Jain
• Created: 29/Jun/09 21:15
• Updated: 28/Jul/17 03:20
• Resolved: 10/Sep/09 18:59

Description

It will be useful to support a new type of join:

say:

.

select .. from JOIN TABLES (A,B,C) WITH KEYS (A.key, B.key, C.key) where ....

The semantics are that for a given key only 1 row is created - nulls are present for the the tables which do not contain a row for that key.
There is no limit on the number of tables, the number of keys should be the same as the number of tables.