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https://issues.apache.org/jira/browse/DERBY-6003?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13507501#comment-13507501
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Mike Matrigali commented on DERBY-6003:
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Changes look good to me.
With respect to downgrade issue, I wonder if it is necesary. I don't
understand the performance impact, but a little concerned that we are
penalizing a lot of users that will not see the problem.
At least in the cases where an apache release exists that fixes the bugs with
usual handling of upgrade and downgrade, should we still disable the trigger
performance because user may
downgrade to a release known release with more bugs, ie. say db version is 10.8
and latest 10.8 release has all fixes.
Also to understand the range of your changes, do you plan on backporting the
downgrade changes, or will these just be in 10.10 software and above?
I understand it helps with the tests. In general I think we expect to people
to at least be able to software upgrade to the latest bug fix release on a
given branch. As we decided previously
it was reasonable if version X.1 could not boot because of bug that user could
could use X.2. Now if there are no available apache releases for a given
version your fix seems like an excellent
help to those users stuck at that release.
> Create row templates outside of the generated code
> --------------------------------------------------
>
> Key: DERBY-6003
> URL: https://issues.apache.org/jira/browse/DERBY-6003
> Project: Derby
> Issue Type: Improvement
> Components: SQL
> Affects Versions: 10.10.0.0
> Reporter: Knut Anders Hatlen
> Assignee: Knut Anders Hatlen
> Priority: Minor
> Attachments: d6003-1a-cleanup.diff, d6003-2a-unused-field.diff,
> d6003-3a-safe-downgrade.diff
>
>
> The constructors for many of the result set classes take GeneratedMethod
> parameters that create row templates (an ExecRow of a certain size and column
> types, each column initialized to an SQL null value).
> As an alternative, the compiler could produce an ExecRow instance and put it
> into the savedObjects field of GenericPreparedStatement, and the constructors
> could take parameter that points to the object in savedObjects. Where the
> result sets currently invoke the generated method to produce a fresh
> template, they could instead clone the saved object.
> Advantages with the suggested approach would be:
> - Reduce the size of the code generator, which should reduce total code
> complexity.
> - Reduce the amount of generated code, which makes it easier for tools
> (profilers, static code analyzers, IDEs) to map executable code to source
> code.
> - Reduce the actual number of generated methods, which makes it less likely
> that queries need to use reflection to invoke the remaining generated methods
> (there's a switchover from DirectCall to ReflectCall when the number of
> generated methods exceeds 10).
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