[HIVE-4751] Support distinct aggregations

• Type: Sub-task
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Component/s: Query Processor
• Assignee: Yin Huai
• Reporter: Yin Huai
• Created: 18/Jun/13 18:29
• Updated: 18/Jun/13 18:35

Description

Right now, the query shown below cannot be optimized by correlation optimizer because for distinct aggregations, distinct columns will be added into the sorting keys.

SELECT a.key AS key1, a.cnt AS cnt1, b.key AS key2, b.cnt AS cnt2
FROM (SELECT x.key as key, count(DISTINCT x.value) AS cnt FROM src x group by x.key) a
JOIN (SELECT y.key as key, count(DISTINCT y.value) AS cnt FROM src1 y group by y.key) b
ON (a.key = b.key)