[jira] [Assigned] (CALCITE-3143) Dividing NULLIF clause may cause Division by zero error

["Feng Zhu (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/CALCITE-3143?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Feng Zhu reassigned CALCITE-3143:
---------------------------------

    Assignee: Feng Zhu

> Dividing NULLIF clause may cause Division by zero error
> -------------------------------------------------------
>
>                 Key: CALCITE-3143
>                 URL: https://issues.apache.org/jira/browse/CALCITE-3143
>             Project: Calcite
>          Issue Type: Bug
>    Affects Versions: 1.16.0
>            Reporter: Li Xian
>            Assignee: Feng Zhu
>            Priority: Critical
>
> execution of query with pattern like below (column COL_A with type BigDecimal) 
> {code:java}
> select case when a < 77 and a > 0 then 99 else 88 end from
> (
>   select SUM(COL_A) / nullif(SUM(0),0) as a
>   from SOME_TABLE group by COL_B
> )
> {code}
>  
> will cause error java.lang.ArithmeticException: Division by zero.
> And the generated code is like below. Division is executed on _input2 (which is 0)
> {code:java}
> /* 154 */ public Object current() {
> /* 155 */ final Object[] current = (Object[]) inputEnumerator.current();
> /* 156 */ final java.math.BigDecimal inp1_ = current[1] == null ? (java.math.BigDecimal) null : org.apache.calcite.runtime.SqlFunctions.toBigDecimal(current[1]);
> /* 157 */ final int inp2_ = org.apache.calcite.runtime.SqlFunctions.toInt(current[2]);
> /* 158 */ final boolean v0 = inp2_ != 0;
> /* 159 */ final java.math.BigDecimal v2 = org.apache.calcite.runtime.SqlFunctions.divide(inp1_, new java.math.BigDecimal(
> /* 160 */ inp2_));
> /* 161 */ return new Object[] {
> /* 162 */ inp1_ != null && v0 && org.apache.calcite.runtime.SqlFunctions.lt(v2, $L4J$C$new_java_math_BigDecimal_77_) && (inp1_ != null && v0 && org.apache.calcite.runtime.SqlFunctions.gt(v2, $L4J$C$new_java_math_BigDecimal_0_)) ? 99 : 88,
> /* 163 */ current[2]};
> /* 164 */ }
> {code}
>  
>  
> And by tracing the code generation, I found that in org.apache.calcite.adapter.enumerable.RexImpTable#implementNullSemantics
> {code:java}
> case FALSE:
>   // v0 != null && v1 != null && f(v0, v1)
>   for (Ord<RexNode> operand : Ord.zip(call.getOperands())) {
>     if (translator.isNullable(operand.e)) {
>       list.add(
>           translator.translate(
>               operand.e, NullAs.IS_NOT_NULL));
>       translator = translator.setNullable(operand.e, false);
>     }
>   }
>   list.add(implementCall(translator, call, implementor, nullAs));
>   return Expressions.foldAnd(list);
> {code}
> operand "SUM(COL_A) / nullif(SUM(0),0)" is set as nullable=false and caused this error.
> My understanding is that since operands are translated as NullAs.IS_NOT_NULL, it's then safe to evaluate them as nullable=false. But in my case, the evaluation with nullable=false will make "nullif(SUM(0), 0)" to be translated to 0, and cause problem on the division. 
> After comment out the below line
> {code:java}
> translator = translator.setNullable(operand.e, false);{code}
> the query will work. May I ask if it is ok to comment out that line? cause that looks like solving my problem temporarily. 
>  



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