[jira] [Commented] (CALCITE-4263) Clarify RelNode#estimateRowCount behavior with regards to nulls

["Chunwei Lei (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CALCITE-4263?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17334417#comment-17334417 ] 

Chunwei Lei commented on CALCITE-4263:
--------------------------------------

+1

> Clarify RelNode#estimateRowCount behavior with regards to nulls
> ---------------------------------------------------------------
>
>                 Key: CALCITE-4263
>                 URL: https://issues.apache.org/jira/browse/CALCITE-4263
>             Project: Calcite
>          Issue Type: Sub-task
>          Components: core
>    Affects Versions: 1.25.0
>            Reporter: Vladimir Sitnikov
>            Priority: Blocker
>
> {{RelNode#estimateRowCount}} implementation must return non-nullable value, and it often uses metadata which might return {{null}}
> For instance,
> {code:java}
> class Correlate {
>   @Override public double estimateRowCount(RelMetadataQuery mq) {
>     double leftRowCount = mq.getRowCount(left); // <-- NPE here
>     switch (joinType) {
>     case SEMI:
>     case ANTI:
>       return leftRowCount;
>     default:
>       return leftRowCount * mq.getRowCount(right); // <-- NPE here
>     }
>   }
> {code}
> There should be documentation on the desired behavior in case metadata returns "unknown", and the code needs adjustment as lot of the implementation perform blind unboxing.



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