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https://issues.apache.org/jira/browse/CALCITE-2970?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16970751#comment-16970751
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Stamatis Zampetakis commented on CALCITE-2970:
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Let me try to sketch a bit what I have in mind. I would like to keep, if
possible, the creation of {{EnumerableSort}} (and other similar enforce
operators) in rule or rule-like structures. We could have for instance a
{{EnforcerRule}} (or change a bit the existing {{ConverterRule}}) which among
other things has a method (canConvert(RelTraitSet toTraits,...)}}) and is
called in the same way as {{RelTraitDef#canConvert}}. Then we have specific
rules like {{EnumerableSortRule}} extending {{EnforcerRule}} which can check if
they can answer positively to the {{canConvert}} method and apply the
transformation.
For the example above consider that the requested {{toTraits}} is ENUMERABLE.
[0] and our {{EnumerableSortRule#canConvert}} method performs the following
check ENUMERABLE. [] satisfies ENUMERERABLE. [0]. The answer is true so the
rule fires and applies the transformation introducing EnumerableSort.
Sorry I don't have time right now to provide a detailed description but I will
try to do it in the following weeks.
> Performance issue when enabling abstract converter for EnumerableConvention
> ---------------------------------------------------------------------------
>
> Key: CALCITE-2970
> URL: https://issues.apache.org/jira/browse/CALCITE-2970
> Project: Calcite
> Issue Type: Bug
> Components: core
> Reporter: Haisheng Yuan
> Priority: Major
> Labels: pull-request-available
> Time Spent: 1h 20m
> Remaining Estimate: 0h
>
> If we enable the use of abstract converter for {{EnumerableConvention}}, by
> making {{useAbstractConvertersForConversion}} return true,
> {{JDBCTest.testJoinManyWay}} will not complete.
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