[teiid-issues] [JBoss JIRA] Issue Comment Edited: (TEIID-1448) XMLTABLE processing should support streaming when possible

[Steven Hawkins (JIRA)]

    [ https://issues.jboss.org/browse/TEIID-1448?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12607905#comment-12607905 ] 

Steven Hawkins edited comment on TEIID-1448 at 6/10/11 2:00 PM:
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Integrated XOM/NUX for situations where simple context item xquery expressions and path expressions allow for subtrees to be processed independently.  The reference guide was updated with the current limitations (in short, context expressions must be a simple path to a non-root element).

We can look at expanding the logic later to handle predicates or other more complicated expressions.  

Example workaround to simplify the context expression:

If a user wishes to perform streaming but wants a predicate applied, they would omit the predicate from the context path and instead use criteria to filter results.

So instead of:

SELECT * FROM XMLTABLE('/a/b[@x=1]/c' PASSING doc COLUMNS z string) t

they would use:

SELECT * FROM XMLTABLE('/a/b/c' PASSING doc COLUMNS z string, x integer PATH '../@x') t WHERE x = 1


      was (Author: shawkins):
    Integrated XOM/NUX for situations where simple context item xquery expressions and path expressions allow for subtrees to be processed independently.  The reference guide was updated with the current limitations (in short, context expressions must be a simple path to a non-root element).

We can look at expanding the logic later to handle predicates or other more complicated expressions.  

Example workaround to simplify the context expression:

If a user wishes to perform streaming but wants a predicate applied, they would omit the predicate from the context path and instead use criteria to filter results.

So instead of:

SELECT * FROM XMLTABLE('/a/b[\@x=1]/c' PASSING doc COLUMNS z string) t

they would use:

SELECT * FROM XMLTABLE('/a/b/c' PASSING doc COLUMNS z string, x integer PATH '../@x') t WHERE x = 1

  
> XMLTABLE processing should support streaming when possible
> ----------------------------------------------------------
>
>                 Key: TEIID-1448
>                 URL: https://issues.jboss.org/browse/TEIID-1448
>             Project: Teiid
>          Issue Type: Feature Request
>          Components: Query Engine
>    Affects Versions: 7.1
>            Reporter: Steven Hawkins
>            Assignee: Steven Hawkins
>             Fix For: 7.4.1
>
>
> Just like the old xml/relational processing if the xpaths/xquery used is sufficiently restrictive the xml can be processed in a streaming fashion - where independent siblings are processed independently without loading the rest of the document.

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