[teiid-issues] [JBoss JIRA] (TEIID-2381) Expanded source hint support

Thu Apr 11 10:38:57 EDT 2013

    [ https://issues.jboss.org/browse/TEIID-2381?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12766510#comment-12766510 ] 

Steven Hawkins commented on TEIID-2381:
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Here's what I can glean as a possible set of changes:

1. allow the source hint to appear for any Teiid query/subquery and not just at the root level
2. at the start of optimization associate the hints with each source access as appropriate (which would be an accumulation)
 2.a Ideally introduce a syntax to associate source hints with a particular access (such as one side of a non-pushdown self-join).  - e.g. SELECT /\*+sh:'foo' oracle[1]:'leading' \*/ or just [1] where the id would come from a numbering of the initial plan tree (not the final processing plan node id).  The issue here is that the only access to the initial plan structure is provided through debug logs.  The other possibility would be to use a form of the oracle global hint syntax - /\*+sh:'foo' vw.tbl:'leading' \*/ - which would need some way to disambiguate from just simple source names.
 2.b the structure of the accumulation would probably just be a list rather than a tree, but that will make it so hints from cousins/siblings in the initial plan hierarchy have awkward relative ordering.
3. allow a higher level hint to specify whether it overrides lower hints

> Expanded source hint support
> ----------------------------
>
>                 Key: TEIID-2381
>                 URL: https://issues.jboss.org/browse/TEIID-2381
>             Project: Teiid
>          Issue Type: Enhancement
>          Components: Query Engine
>            Reporter: Steven Hawkins
>            Assignee: Steven Hawkins
>         Attachments: HintsExecutionFactory.java, RandomExecutionFactory.java, RandomNumberStoredProcedureExecution.java, SysviewHintsExecutionTest.java
>
>
> We currently look at the source hint in only the root user query (not in subqueries nor the with clause) and only consider it in a very narrow set of circumstances when it's used in a view.

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