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Posted to issues@calcite.apache.org by "Zhong Yu (JIRA)" <ji...@apache.org> on 2018/04/19 11:53:00 UTC

[jira] [Created] (CALCITE-2267) AbstractRelNode.getId() may produce duplicate IDs

Zhong Yu created CALCITE-2267:
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             Summary: AbstractRelNode.getId() may produce duplicate IDs
                 Key: CALCITE-2267
                 URL: https://issues.apache.org/jira/browse/CALCITE-2267
             Project: Calcite
          Issue Type: Bug
          Components: core
            Reporter: Zhong Yu
            Assignee: Julian Hyde


RelOptNode.getId() is supposed to be unique per instance; however, the generation of AbstractRelNode.id is not thread safe; in a multithreaded environment, the behavior is undeterministic, and there is a non-trivial possibility that duplicate IDs are generated for different nodes.

This ID is used for comparing nodes in several places, therefore it may affect program stability and correctness. For example, if we set id=0 for all nodes, Calcite's own test suite will have multiple failures. 

In our own test environment, the optimizers are expected to be deterministic, yet occasionally they mysteriously produce different plans. While we cannot be 100% sure that it is caused by AbstractRelNode.id, we can verify that fudging with the ID will reliably change the output of our optimizers.



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