[teiid-issues] [JBoss JIRA] Commented: (TEIID-43) command deterministic subqueries without from clauses should be merged if possible

[Steven Hawkins (JIRA)]

    [ https://issues.jboss.org/browse/TEIID-43?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12578094#comment-12578094 ] 

Steven Hawkins commented on TEIID-43:
-------------------------------------

The original customer issue I believe was around using views that were defined as a select without a from were inhibiting pushdown.  That will no longer happen as an uncorrelated scalar subqueries, since they are eligible for evalaution prior to pushdown.

Introducing a broad fix to enhance the usage of a select without a from as an inline view in a join does not seem necessary.  There will only be an issue if that join is below a higher level outer join, and thus can't be rearranged properly for pushdown.

One fix would be to allow ruleraiseaccess to see if a join child without a model can support the source/project nodes so that the access node can be raised (specific to select without a from).
Another fix (which doesn't preclude the first) would be to do more analysis to group joins under outer joins more appropriately based upon the join criteria used.

> command deterministic subqueries without from clauses should be merged if possible
> ----------------------------------------------------------------------------------
>
>                 Key: TEIID-43
>                 URL: https://issues.jboss.org/browse/TEIID-43
>             Project: Teiid
>          Issue Type: Bug
>          Components: Query Engine
>    Affects Versions: 6.0.0
>            Reporter: Steven Hawkins
>            Priority: Optional
>             Fix For: 7.4
>
>
> Defect Tracker #24752: command deterministic subqueries without from clauses should be merged if possible:
> i.e. select e1, a from pm1.g1, (select 1 a) x <=> select e1, 1 from pm1.g1
> i.e. select e1, (select 1 a)  from pm1.g1  <=> select e1, 1 from pm1.g1

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