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https://issues.apache.org/jira/browse/DERBY-2487?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12675691#action_12675691
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Knut Anders Hatlen commented on DERBY-2487:
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Hi Bryan,
I haven't looked at the patch yet, but I've had a brief look at the
documentation that you posted on DERBY-4065 (great work, by the way!), and I
noticed that the STMT_TEXT column in SYSXPLAIN_STATEMENTS was of type LONG
VARCHAR (length 32700). Given that the maximum length of VARCHAR is just 28
characters shorter than LONG VARCHAR, do you think it would be a good idea to
change the data type of that column to VARCHAR? That would allow comparisons on
that column without a cast. Otherwise, I think a statement like "select * from
sys.sysxplain_statements where stmt_text='select * from t'" would result in
ERROR 42818: Comparisons between 'LONG VARCHAR (UCS_BASIC)' and 'CHAR
(UCS_BASIC)' are not supported.
> Enhance Derby with EXPLAIN Functionality
> ----------------------------------------
>
> Key: DERBY-2487
> URL: https://issues.apache.org/jira/browse/DERBY-2487
> Project: Derby
> Issue Type: New Feature
> Components: SQL
> Affects Versions: 10.2.2.0
> Reporter: Felix Beyer
> Assignee: Bryan Pendleton
> Priority: Minor
> Attachments: Derby physical XPLAIN schema.png,
> incorporateTrunkChanges.diff, RSProtocolNew.pdf, rts.xls, small logical
> xplain schema.pdf, startRegressionTest.diff, updateRegressionTests.diff,
> updateRegressionTests.diff, usage.txt, xplain_patch_v1.txt, xplainClasses.pdf
>
>
> This enhancement extends Derby with EXPLAIN functions. Users want to have
> more feedback than they`re getting with the current RuntimeStatistics
> facility. This extension is based on the
> RuntimeStatistics/ResultSetStatistics functions / classes.
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