[teiid-issues] [JBoss JIRA] (TEIID-2481) common table (with) push down improvements
Steven Hawkins (JIRA)
issues at jboss.org
Wed Oct 15 11:55:35 EDT 2014
[ https://issues.jboss.org/browse/TEIID-2481?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Work on TEIID-2481 stopped by Steven Hawkins.
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> common table (with) push down improvements
> ------------------------------------------
>
> Key: TEIID-2481
> URL: https://issues.jboss.org/browse/TEIID-2481
> Project: Teiid
> Issue Type: Enhancement
> Components: Query Engine
> Reporter: Steven Hawkins
> Assignee: Steven Hawkins
> Fix For: 8.10
>
>
> The general strategy for with pushdown should better handle:
> - a with clause that can be pushed against a source that does not support common table. If a single reference or some other sufficient condition is met then we should just inline the pushdown rather than inhibiting the whole query from pushing down.
> - even if a source supports with pushdown, it may be more performant in some circumstances to inline the common table reference (such as only a single reference). This is complicated slightly by subqueries.
> - alternatively in some situations even if a with clause can be pushed, it may be better to not perform the pushdown -e.g. two separate pushdown accesses to a common table that is expensive to compute (this may need to be hint driven).
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