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https://issues.apache.org/jira/browse/DERBY-6075?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13613392#comment-13613392
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Bryan Pendleton commented on DERBY-6075:
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Thanks for the follow-up and the nice breakdown, Knut Anders.

This information is very valuable; it would be neat if we could figure out some
way to incorporate it into, say, our release notes, since as you say this is
good news and backed up by solid evidence.

It's great to see that all the hard work that you and others on the team have
been putting into performance is paying off. I'm looking forward to using the
new release even more now!

                
> Use modern collections in impl/sql/compile
> ------------------------------------------
>
>                 Key: DERBY-6075
>                 URL: https://issues.apache.org/jira/browse/DERBY-6075
>             Project: Derby
>          Issue Type: Bug
>          Components: SQL
>    Affects Versions: 10.10.1.1
>            Reporter: Knut Anders Hatlen
>            Assignee: Knut Anders Hatlen
>            Priority: Minor
>         Attachments: Compile.java, d6075-10a-aggregate-vectors.diff, 
> d6075-11a-remaining-vectors.diff, d6075-12a-stack.diff, 
> d6075-13a-unused-properties.diff, d6075-14a-dead-syntax.diff, 
> d6075-15a-sqlgrammar-vectors.diff, d6075-16a-negative-test.diff, 
> d6075-17a-rename-aggregate-vectors.diff, d6075-1a-CollectNodesVisitor.diff, 
> d6075-2a-bindExpression.diff, d6075-3a-javadoc.diff, 
> d6075-4a-parameterList.diff, d6075-5a-ordering.diff, 
> d6075-6a-DMLModStatementNode.diff, d6075-7a-more-signatures.diff, 
> d6075-8a-local-hashtables.diff, d6075-9a-hashtable-fields.diff
>
>
> The code in the org.apache.derby.impl.sql.compile package predates the Java 
> Collections Framework and uses old-style collections like java.util.Vector 
> and java.util.Hashtable. Since the old-style collection classes are used in 
> many method signatures, it's difficult to use modern collection classes when 
> adding new code.
> I suggest we switch to using interfaces (like java.util.List and 
> java.util.Map) instead of specific classes in the signatures, so that we have 
> more flexibility in choosing the right collection class for the job.
> Only changing the signatures would allow us to continue using Vector and 
> Hashtable, since they implement the interfaces. However, I think it would be 
> good to switch to ArrayList and HashMap in a second step. The instances in 
> impl/sql/compile are not shared between threads, so we don't need the 
> synchronization provided by the old-style classes. Switching to 
> unsynchronized classes may make compilation slightly faster.

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