Jason Phelps created IMPALA-5936:
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Summary: Difference between the % Operator and Mod function with
large decimal values
Key: IMPALA-5936
URL: https://issues.apache.org/jira/browse/IMPALA-5936
Project: IMPALA
Issue Type: Bug
Reporter: Jason Phelps
It looks like the '%' operator breaks in the following scenario:
decimal(18,0) + Any value greater than INT (2147483647)
As far as I can tell, `%` will typically use the proper mod function
transparently, but instead of using/casting as BIGINT, it will use INT, and
then overflow. If I directly cast as BIGINT, it will work as expected.
+-------------+---------+-------------+
| num | num % 3 | mod(num, 3) |
+-------------+---------+-------------+
| 42607032167 | -2 | 2 |
| 42606774111 | -1 | 0 |
| 42363009429 | -1 | 0 |
| 42603003271 | 0 | 1 |
| 42606961501 | 0 | 1 |
| 42608445511 | 0 | 1 |
| 42607368197 | -2 | 2 |
| 42606319059 | -1 | 0 |
| 42602678339 | -2 | 2 |
| 42260146355 | -2 | 2 |
+-------------+---------+-------------+
If the number is used directly (i.e. not using a column), it works as expected:
+-----------------+---------------------+
| 42607032167 % 3 | mod(42607032167, 3) |
+-----------------+---------------------+
| 2 | 2 |
+-----------------+---------------------+
According to the documentation, these should be equivalent
{quote}mod(numeric_type a, same_type b)
Purpose: Returns the modulus of a number. Equivalent to the % arithmetic
operator. Works with any size integer type, any size floating-point type, and
DECIMAL with any precision and scale.
{quote}
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