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https://issues.apache.org/jira/browse/CALCITE-3503?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16978665#comment-16978665
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Xiening Dai commented on CALCITE-3503:
--------------------------------------
I explained this before. The reason to create a new MQ instance is to avoid
polluting meta data cache (RelMetadataQueryBase#map). As discussed with
[~julianhyde], we don't want isValid() to have any side effect. Otherwise
turning on and off DEBUG mode could result in different planner behaviors,
which is absolutely not we want.
I also want to point out that this behavior (creating a new MQ instance) is
part to the change CALCITE-2018, not something new with this patch.
CALCITE-2018 was reviewed and signed off by multiple person including you. If
you feel we want to revisit that decision, we should discuss in 2018 or a
separate JIRA.
> NPE at VolcanoPlanner#isValid when DEBUG is enabled
> ---------------------------------------------------
>
> Key: CALCITE-3503
> URL: https://issues.apache.org/jira/browse/CALCITE-3503
> Project: Calcite
> Issue Type: Bug
> Components: core
> Affects Versions: 1.21.0
> Reporter: Stamatis Zampetakis
> Priority: Blocker
> Labels: pull-request-available
> Fix For: 1.22.0
>
> Time Spent: 3h
> Remaining Estimate: 0h
>
> The stacktrace is the following:
> {noformat}
> java.lang.NullPointerException
> at
> org.apache.calcite.plan.volcano.VolcanoPlanner.isValid(VolcanoPlanner.java:880)
> at
> org.apache.calcite.plan.volcano.VolcanoPlanner.ensureRegistered(VolcanoPlanner.java:870)
> at
> org.apache.calcite.plan.volcano.VolcanoPlanner.ensureRegistered(VolcanoPlanner.java:92)
> at
> org.apache.calcite.rel.AbstractRelNode.onRegister(AbstractRelNode.java:321)
> at
> org.apache.calcite.plan.volcano.VolcanoPlanner.registerImpl(VolcanoPlanner.java:1701)
> at
> org.apache.calcite.plan.volcano.VolcanoPlanner.setRoot(VolcanoPlanner.java:298)
> at
> org.apache.calcite.tools.Programs.lambda$standard$3(Programs.java:269)
> {noformat}
> According to [~volodymyr] this is a regression caused by CALCITE-3487.
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