[CALCITE-2355] Add multiset operators MULTISET UNION, IS A SET, FUSION, etc.

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.17.0
• Component/s: core
• Assignee: Julian Hyde
• Reporter: Sergey Nuyanzin
• Created: 07/Jun/18 12:43
• Updated: 20/Jul/18 08:18
• Resolved: 13/Jun/18 23:59

Description

While working on https://issues.apache.org/jira/browse/FLINK-4542 I realized that most of the multiset operations do not work and skipped in tests with

if (TODO) 

. So here I propose to fix it.
Here it is my branch with fixes and tests
Currently it is done for

IS A SET
IS NOT A SET
IS EMPTY
IS NOT EMPTY
MEMBER OF
MULTISET INTERSECT
MULTISET INTERSECT ALL
MULTISET UNION
MULTISET UNION ALL
MULTISET EXCEPT
MULTISET EXCEPT ALL
SUBMULTISET OF
NOT SUBMULTISET OF

may be the only one which is not done yet is FUSION

by the way I have a question: is it ok that default case for MULTISET INTERSECT/UNION /EXCEPT is DISTINCT (here ) ? At the same time Oracle behaves in the opposite way (e.g. here https://docs.oracle.com/cd/B19306_01/server.102/b14200/operators006.htm)

https://github.com/apache/calcite/compare/master...snuyanzin:CALCITE_MULTISETS
I can make a PR if nobody minds