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https://issues.apache.org/jira/browse/DERBY-6075?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Knut Anders Hatlen updated DERBY-6075:
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Attachment: d6075-8a-local-hashtables.diff
Attaching d6075-8a-local-hashtables.diff which changes some Hashtables to
HashSets. All the Hashtables were private to the methods in which they were
created, so Hashtable synchronization were not necessary. Also, only the hash
keys were ever looked at, so they could be replaced with HashSets rather than
HashMaps.
All the regression tests ran cleanly with the patch.
> 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: 10.10.0.0
> Reporter: Knut Anders Hatlen
> Assignee: Knut Anders Hatlen
> Priority: Minor
> Attachments: 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
>
>
> 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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