[teiid-issues] [JBoss JIRA] (TEIID-3009) perform projection minimization on with commands

[Steven Hawkins (JIRA)]

     [ https://issues.jboss.org/browse/TEIID-3009?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Steven Hawkins resolved TEIID-3009.
-----------------------------------

    Resolution: Done


The logic here will replace any unused projection with a null value - to keep the definition of the cte consistent.  The logic is not quite as clean as I would like as it's done in a preprocessing step in relationalplanner and requires some temp plans and additional runs of ruleassignoutputelements.  The optimization is not completely deep.  Usage of a CTE in any subquery (including other CTEs) will be seen as required - regardless of whether the subquery will actually exist in the final plan form.  We'd need better iterative facilities to do any better as that would currently be quite expensive.

This commit also corrected an issue with the assignment of with clauses to pushdown queries.  The old code did not deeply check for usage.

> perform projection minimization on with commands
> ------------------------------------------------
>
>                 Key: TEIID-3009
>                 URL: https://issues.jboss.org/browse/TEIID-3009
>             Project: Teiid
>          Issue Type: Sub-task
>      Security Level: Public(Everyone can see) 
>          Components: Query Engine
>            Reporter: Steven Hawkins
>            Assignee: Steven Hawkins
>             Fix For: 8.9
>
>
> We currently treat the with clause as the creation of a temporary table at a query scope, but we can do projection minimization based upon the referenced columns.  This is somewhat tricky with the current planning logic as we must first plan the with clause to determine if it's eligible for pushdown to then plan the main command.  



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