[IMPALA-1300] Unioning queries with subqueries could be supported

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: Impala 2.0
• Fix Version/s: Impala 2.1
• Assignee: Dimitris Tsirogiannis
• Reporter: casey
• Created: 23/Sep/14 22:31
• Updated: 18/Oct/14 18:36
• Resolved: 18/Oct/14 18:36

Description

The query below is rejected in analysis but could be allowed

Query: 
  select COUNT(*) FROM alltypestiny WHERE int_col = (SELECT 1) 
UNION 
  SELECT int_col FROM alltypestiny
ERROR: AnalysisException: Unsupported statement containing subqueries: SELECT count(*) FROM functional.alltypestiny WHERE int_col = (SELECT 1) UNION SELECT int_col FROM functional.alltypestiny

is the same as

Query: 
  select count(*) 
  FROM functional.alltypestiny 
  LEFT SEMI JOIN (SELECT 1 `$c$1`) `$a$1` ON int_col = `$a$1`.`$c$1` 
UNION 
  SELECT int_col FROM functional.alltypestiny
+----------+
| count(*) |
+----------+
| 4        |
| 1        |
| 0        |
+----------+