[teiid-issues] [JBoss JIRA] Updated: (TEIID-1474) Add query hint to limit parallel execution of union members
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https://issues.jboss.org/browse/TEIID-1474?page=com.atlassian.jira.plugin...
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Steven Hawkins updated TEIID-1474:
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Fix Version/s: 7.4
Component/s: Query Engine
Affects: [Documentation (Ref Guide, User Guide, etc.), Release Notes]
The config now has userRequestSourceConcurrency, which is also covered in the admin guide,
to limit parallel source execution on a per user query basis. Having a hint override this
value is now straight-forward to implement, but it would take effect for the entire user
query, rather than a specific union or join. Would that cover your usecase, or would you
need control down to a specific operation?
Add query hint to limit parallel execution of union members
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Key: TEIID-1474
URL: https://issues.jboss.org/browse/TEIID-1474
Project: Teiid
Issue Type: Feature Request
Components: Query Engine
Reporter: Howard Abrams
Assignee: Steven Hawkins
Fix For: 7.4
We would like a new query hint to limit the number of parallel executions of union
members. This is useful in two situations:
1. When the queries are expensive, but the overall union contains a limit that is most
likely to be fulfilled by the first member of the union
2. When the queries are backed by a common resource which may be overloaded by multiple
queries
The addition of a hint would make this manageable by the client; perhaps something like
"/*+ parallel=2*/"?
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