[teiid-issues] [JBoss JIRA] Created: (TEIID-1376) Add support for pushing joins through a union

[Steven Hawkins (JIRA)]

Add support for pushing joins through a union
---------------------------------------------

                 Key: TEIID-1376
                 URL: https://jira.jboss.org/browse/TEIID-1376
             Project: Teiid
          Issue Type: Feature Request
          Components: Query Engine
    Affects Versions: 7.2
            Reporter: Steven Hawkins
            Assignee: Steven Hawkins
             Fix For: 7.3


Given a query structure such as:

inner join
   union all
     a
     b
   union all
     c
     d

where a,b,c,d are access nodes to a source that supports joins and there is a constant column projected by each union branch and that column is used in the join predicates, then we should be able examine

union all
  inner join
    a
    b
  inner join
    a
    c
...

to determine if any of the joins will no longer be necessary. 

This is a possible pattern in a multi-source or partitioning scenario.  

In some scenarios there may not be an actual projected literal, which could be accommodated if a foreign key could be marked as partitioned.



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