[teiid-issues] [JBoss JIRA] (TEIID-1990) UNION pushdown
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https://issues.jboss.org/browse/TEIID-1990?page=com.atlassian.jira.plugin...
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Steven Hawkins commented on TEIID-1990:
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The debug log shows that only some of the access nodes have been raised above their parent
project nodes after RuleRaiseAccess. The most likely reason is that the source does not
support projecting non-column reference expressions. See
ExecutionFactory.supportsSelectExpression. We should though add a debug line to the debug
log stating why the pushdown has been prevented, which is typically done for criteria
pushing but has not yet been added for all other situations.
UNION pushdown
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Key: TEIID-1990
URL: https://issues.jboss.org/browse/TEIID-1990
Project: Teiid
Issue Type: Bug
Reporter: Mark Addleman
Assignee: Steven Hawkins
Attachments: plan.txt, plan.txt
I have SQL of the form
SELECT a FROM (
SELECT a FROM ds.t1 UNION
SELECT a FROM ds.t2
) t
The execution factory extends JDBCExecutionFactory and supports everything except row
offset. It appears that the two unioned SELECTs are being executed as separate statements
rather than the entire unioned set being pushed down to the datasource.
Attached is plan
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