Yuwei Fu created BEAM-10379:
-------------------------------
Summary: Some problems when implementing BIT_AND aggregation
function in BeamSQL
Key: BEAM-10379
URL: https://issues.apache.org/jira/browse/BEAM-10379
Project: Beam
Issue Type: Task
Components: dsl-sql, dsl-sql-zetasql
Reporter: Yuwei Fu
Performs a bitwise AND operation on expression and returns the result.
Supported Argument Types: INT64
Returned Data Types: INT64
Examples
{code:sql}
SELECT BIT_AND(c) as bit_and FROM UNNEST([0xF001, 0x00A1]) as c;
+---------+
| bit_and |
+---------+
| 1 |
+---------+
{code}
What is expected: should include both Calcite and ZetaSQL dialects.
How to test: unit tests
Reference:
[https://cloud.google.com/bigquery/docs/reference/standard-sql/aggregate_functions#bit_and]
Problems:
After implementation, the current situation is:
# When table is empty, the result is empty, correct.
# When table contains only null values, the result is null, correct.
# When table contains only valid numerical values, the result is as expected,
correct.
# When table contains both valid numerical values and null values, the result
should be null, but it seems all null values have been directly ignored before
doing the bit_and operation. Only numerical values are taken into operation, so
the result is incorrect.
It turns out that on direct runner, NULL will not be passed to CombineFn thus
all NULL inputs are ignored. And then if there is any non-null inputs, bit_and
will be applied on them only, which leads to a non-null result, which is not
correct.
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