[CALCITE-1990] Make RelDistribution extend RelMultipleTrait

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.15.0
• Assignee: Julian Hyde
• Reporter: LeoWangLZ
• Created: 21/Sep/17 14:49
• Updated: 13/Dec/17 02:26
• Resolved: 06/Nov/17 17:04

Description

In Distributed System, RelDistribution is used for Exchange or SortExchange. for some operators it may deliver RelDistribution Trait, but some operator like SortedMergeJoin may deliver multiple traits.
eg:

Query:
select * from T1 join T2 on T1.c1=T2.d1;

Suppose Plan:
SortedMergeJoin
    Exchange(c1)
        T1(c1)
    Exchange(d1)
        T2(d1)

than SortedMergeJoin can deliver RelDistribution(hash[c1]) or RelDistribution(hash[d1]).
we can consider RelDistribution extend RelMultipleTrait like RelCollation.
EnumerableMergeJoin is the case for RelCollation, and RelDistribution is also fit for SortedMergeJoin in Distributed system