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From "ASF GitHub Bot (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (FLINK-8139) Check for proper equals() and hashCode() when registering a table
Date Thu, 07 Dec 2017 10:17:01 GMT

    [ https://issues.apache.org/jira/browse/FLINK-8139?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16281628#comment-16281628

ASF GitHub Bot commented on FLINK-8139:

Github user fhueske commented on the issue:

    Hmm, I agree with @twalthr. Adding these checks when a DataSet/DataStream is imported
would prevent valid queries (e.g., those that to simple transformations). I would not add
a config switch to disable the global checks. Adding the checks to the operators that require
properly implemented `equals()` and `hashCode()` methods sounds like a better approach. 
    We should also add to the documentation that all objects that are processed by the Table
API / SQL should have equals and hashCode properly implemented.

> Check for proper equals() and hashCode() when registering a table
> -----------------------------------------------------------------
>                 Key: FLINK-8139
>                 URL: https://issues.apache.org/jira/browse/FLINK-8139
>             Project: Flink
>          Issue Type: Improvement
>          Components: Table API & SQL
>            Reporter: Timo Walther
>            Assignee: Aegeaner
> In the current Table API & SQL implementation we compare {{Row}}s at different positions.
E.g., for joining we test rows for equality or put them into state. A heap state backend requires
proper hashCode() and equals() in order to work correct. Thus, every type in the Table API
needs to have these methods implemented.
> We need to check if all fields of a row have implement methods that differ from {{Object.equals()}}
and {{Object.hashCode()}} via reflections. Both coming from TableSource and DataStream/DataSet.
> Additionally, for array types, the {{Row}} class should use {{Arrays.deepEquals()}} and
{{Arrays.deepHashCode()}} instead of the non-deep variants.

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