[jira] [Created] (IMPALA-7888) Incorrect NumericLiteral overflow checks for FLOAT, DOUBLE

["Paul Rogers (JIRA)" <ji...@apache.org>]

Paul Rogers created IMPALA-7888:
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             Summary: Incorrect NumericLiteral overflow checks for FLOAT, DOUBLE
                 Key: IMPALA-7888
                 URL: https://issues.apache.org/jira/browse/IMPALA-7888
             Project: IMPALA
          Issue Type: Bug
          Components: Frontend
    Affects Versions: Impala 3.0
            Reporter: Paul Rogers
            Assignee: Paul Rogers


Consider the following (new) unit test:

{code:java}
    assertFalse(NumericLiteral.isOverflow(BigDecimal.ZERO, Type.FLOAT));
{code}

This test fails (that is, the value zero, so the method claims, overflows a FLOAT.)

The reason is a misunderstanding of the meaning of {{MIN_VALUE}} for Float:

{code:java}
      case FLOAT:
        return (value.compareTo(BigDecimal.valueOf(Float.MAX_VALUE)) > 0 ||
            value.compareTo(BigDecimal.valueOf(Float.MIN_VALUE)) < 0);
{code}

For Float, {{MIN_VALUE}} is the smallest positive number that Float can represent:

{code:java}
    public static final float MIN_VALUE = 0x0.000002P-126f; // 1.4e-45f
{code}

The value that the Impala code wants to check it {{- Float.MAX_VALUE}}.

The only reason that this is not marked as more serious is that the method appears to be used in only one place, and that place does not use {{FLOAT}} values.



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