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https://issues.apache.org/jira/browse/DERBY-6211?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13647477#comment-13647477
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Rick Hillegas commented on DERBY-6211:
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Hi Mamta,
I'm not planning to fix anything that isn't broken. I think that the
RuntimeStatisticsParser does a good job of analyzing the plans chosen for many
queries. But I think that there are limitations in the approach taken by
RuntimeStatisticsParser: looking for the presence of specific strings in the
runtime statistics output. For instance, the following RuntimeStatisticsParser
method
public boolean usedTableScan(String tableName)
...will give you useful information if a table is only scanned once by a query.
But if a table is scanned more than once, then the method won't tell you which
scan was the table scan. I'm hoping that a trace plugin will be able to give us
the detailed structure of the plan. Thanks.
> Make Optimizer trace logic pluggable.
> -------------------------------------
>
> Key: DERBY-6211
> URL: https://issues.apache.org/jira/browse/DERBY-6211
> Project: Derby
> Issue Type: Improvement
> Components: SQL
> Affects Versions: 10.11.0.0
> Reporter: Rick Hillegas
> Assignee: Rick Hillegas
> Attachments: derby-6211-01-aa-createPlugin.diff
>
>
> Right now the trace logic in the optimizer is hard-coded to produce a stream
> of diagnostics. It would be good to be able to plug alternative trace logic
> into the optimizer. This would make the following possible:
> 1) Plug in trace logic which produces formats which are easier to study and
> which can be analyzed mechanically. E.g., xml formatted output.
> 2) Plug in trace logic which can be used during unit testing to verify that
> the optimizer has picked the right plan. Over time this might make it easier
> to migrate canon-based tests to assertion-based tests.
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