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Posted to issues-all@impala.apache.org by "Tim Armstrong (JIRA)" <ji...@apache.org> on 2018/11/05 19:28:00 UTC
[jira] [Commented] (IMPALA-7805) NumericLiteral toSql() should
render zero as 0, not 0-E38, 0.000, etc.
[ https://issues.apache.org/jira/browse/IMPALA-7805?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16675650#comment-16675650 ]
Tim Armstrong commented on IMPALA-7805:
---------------------------------------
This would be a step towards sanity. IMPALA-5821 helps by representing type information about numeric literals in a consistent way.
> NumericLiteral toSql() should render zero as 0, not 0-E38, 0.000, etc.
> ----------------------------------------------------------------------
>
> Key: IMPALA-7805
> URL: https://issues.apache.org/jira/browse/IMPALA-7805
> Project: IMPALA
> Issue Type: Improvement
> Components: Frontend
> Affects Versions: Impala 3.0
> Reporter: Paul Rogers
> Assignee: Paul Rogers
> Priority: Minor
>
> Testing of other issues revealed a somewhat bizarre aspect of how the planner expression nodes render 0. {{NumericLiteral.toSql()}} uses the Java {{BigDecimal}} class to convert a numeric value to a string for use in explained plans.
> The default Java behavior is to consider scale when rendering numbers, including 0. Thus, depending on precision and scale, you may get:
> {noformat}
> 0
> 0.0
> 0.00
> 0.000
> ...
> 0E-38
> {noformat}
> Mathematically, zero is zero. Unlike Java, SQL attaches no significance to the decimal point. (In Java, 0 is an integer, 0.0 is a float.) Nor does SQL attach significance to the number of zeros past the decimal point.
> To make testing easier, change the behavior to always emit "0" when the value is zero, regardless of precision or scale.
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