[teiid-issues] [JBoss JIRA] (TEIID-2356) Add a query hint to limit the number of concurrent source queries

[Steven Hawkins (JIRA)]

     [ https://issues.jboss.org/browse/TEIID-2356?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Steven Hawkins updated TEIID-2356:
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          Summary: Add a query hint to limit the number of concurrent source queries  (was: CLONE - Add a query hint to limit the number of concurrent source queries)
    Fix Version/s:     (was: 7.4)


#1 was largely addressed by TEIID-1543

#2 could still be addressed via a hint - with the caveat from TEIID-1543, that the current concurrency throttle is set on the request and is hard to tie to the actual plan
                
> Add a query hint to limit the number of concurrent source queries
> -----------------------------------------------------------------
>
>                 Key: TEIID-2356
>                 URL: https://issues.jboss.org/browse/TEIID-2356
>             Project: Teiid
>          Issue Type: Sub-task
>          Components: Query Engine
>    Affects Versions: 7.4
>            Reporter: Steven Hawkins
>            Assignee: Steven Hawkins
>            Priority: Minor
>
> 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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