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https://issues.apache.org/jira/browse/IMPALA-7805?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Paul Rogers updated IMPALA-7805:
--------------------------------
Description:
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. And, of course,
we're only talking about the output of {{EXPLAIN}}, which is never parsed
anyway (except in tests.)
To make testing easier, change the behavior to always emit "0" when the value
is zero, regardless of precision or scale.
was:
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.
> 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. And, of
> course, we're only talking about the output of {{EXPLAIN}}, which is never
> parsed anyway (except in tests.)
> 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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