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https://issues.apache.org/jira/browse/DERBY-681?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12479436
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A B commented on DERBY-681:
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Thank you for the second patch, Manish. I looked it over and it does indeed
address most of my comments, so I think we're getting closer. The reason I say
"closer" is because I noticed the following problems with the second patch, and
I think these should be addressed before the patch can be committed:
- Looks like the formatting for the first couple of lines in the license
text for views.sql has changed. I assume this was just an accident?
- This patch adds an explicit connection to views.sql, which I do not
think is right:
@@ -17,6 +14,7 @@
-- tests for views
-- set autocommit off
+connect 'jdbc:derby:wombat';
autocommit off;
Notice that the result (in views.out) is a security access violation:
@@ -17,7 +14,9 @@
-- tests for views
-- set autocommit off
-autocommit off;
+connect 'jdbc:derby:wombat';
+JAVA ERROR: java.security.AccessControlException: access denied
(java.util.PropertyPermission ij.URLCheck read)
+ij> autocommit off;
This looks wrong to me. Is the additional connect statement an intentional
change,
or is that just a remnant from some testing you were doing? If possible I
think the
extra call to "connect" should be removed and the master file updated
accordingly.
If you made the change intentionally then can you explain why it is
necessary?
- There is also the following diff in the RunTest and RunSuite classes:
- classpath = sp.getProperty("classpath");
+ classpath = sp.getProperty("java.class.path");
Again, can you explain why this particular change is necessary? Were you
experiencing problems while running the tests? If so, what were those
problems?
Other than these test issues I think the patch is ready for commit...
> Eliminate the parser's rewriting of the abstract syntax tree for queries with
> GROUP BY and/or HAVING clauses
> ------------------------------------------------------------------------------------------------------------
>
> Key: DERBY-681
> URL: https://issues.apache.org/jira/browse/DERBY-681
> Project: Derby
> Issue Type: Improvement
> Components: SQL
> Reporter: Rick Hillegas
> Assigned To: Manish Khettry
> Attachments: 681.patch.txt, 681.patch2.txt, notes.txt
>
>
> If a query contains a GROUP BY or HAVING clause, the parser rewrites the
> abstract syntax tree, putting aggregates into a subselect and treating the
> HAVING clause as the WHERE clause of a fabricated outer select from the
> subquery. This allows the compiler to re-use some machinery since the HAVING
> clause operates on the grouped result the way that the WHERE clause operates
> on the from list. Unfortunately, this rewriting creates an explosion of
> special cases in the compiler after parsing is done. The rewriting is not
> systematically handled later on in the compiler. This gives rise to defects
> like bug 280. We need to eliminate this special rewriting and handle the
> HAVING clause in a straightforward way. This is not a small bugfix but is a
> medium sized project.
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