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From "Rick Hillegas (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (DERBY-6263) Make acceptChildren() overloads visit all clauses in QueryTreeNodes
Date Mon, 17 Jun 2013 13:05:19 GMT

     [ https://issues.apache.org/jira/browse/DERBY-6263?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Rick Hillegas updated DERBY-6263:
---------------------------------

    Attachment: derby-6263-02-aa-ignored-clauses-in-SelectNode.diff

Attaching derby-6263-02-aa-ignored-clauses-in-SelectNode.diff. This patch adds some missing
clauses to SelectNode.acceptChildren(). I am running tests now.

15 test cases involving subqueries broke when I simply added the clauses. The tests work if
I wrap the clauses in a conditional which excludes the HasCorrelatedCRsVisitor Visitor. A
better solution might be to fix that Visitor. But I don't have much context for picking one
solution over another. Hopefully we will get more insight if we systematically study the problem
of missing clauses in the Visitor logic.

Touches the following file:

M       java/engine/org/apache/derby/impl/sql/compile/SelectNode.java

                
> Make acceptChildren() overloads visit all clauses in QueryTreeNodes
> -------------------------------------------------------------------
>
>                 Key: DERBY-6263
>                 URL: https://issues.apache.org/jira/browse/DERBY-6263
>             Project: Derby
>          Issue Type: Bug
>          Components: SQL
>    Affects Versions: 10.11.0.0
>            Reporter: Rick Hillegas
>         Attachments: derby-6263-01-aa-visit-ignored-clauses.diff, derby-6263-02-aa-ignored-clauses-in-SelectNode.diff
>
>
> The acceptChildren() overloads don't visit all of the clauses in an AST node. This is
probably a mistake. However, fixing it will require a systematic analysis of the AST nodes
and probably some changes to the Visitors. Some queries rely on the fact that certain Visitors
will not be called on some AST nodes even though the Visitors are called on sister nodes in
the same parent AST node.
> An example of this defect is the CursorNode. If you call treePrint() on a CursorNode,
you will see information on ORDER BY, FETCH, and OFFSET clauses. However, these clauses are
not visited by CursorNode.acceptChildren(). This looks like an omission. This defect was brought
to our attention by this email thread: http://apache-database.10148.n7.nabble.com/Using-ASTParser-and-TreeWalker-for-parsing-SQL-query-td131219.html.
You can see the difference in treePrint() and acceptChildren() behavior by running the following
query through the ASTParser and TreePrinter tools attached to DERBY-3946:
>     select tablename from sys.systables where 1=2 order by tablename;

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