HuSen8891 commented on code in PR #12811:
URL: https://github.com/apache/datafusion/pull/12811#discussion_r1800472105
##########
datafusion/physical-plan/src/windows/mod.rs:
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@@ -257,31 +257,55 @@ fn create_built_in_window_expr(
}
}
BuiltInWindowFunction::Lag => {
- let arg = Arc::clone(&args[0]);
+ let mut arg = Arc::clone(&args[0]);
let shift_offset = get_scalar_value_from_args(args, 1)?
.map(get_signed_integer)
.map_or(Ok(None), |v| v.map(Some))?;
- let default_value =
- get_casted_value(get_scalar_value_from_args(args, 2)?,
out_data_type)?;
+ // If value is NULL, we use default data type as output data type,
no need to cast data type
+ let default_value = match out_data_type {
+ DataType::Null => match get_scalar_value_from_args(args, 2)? {
+ Some(value) => {
+ let null_value =
ScalarValue::try_from(value.data_type())?;
+ arg = Arc::new(Literal::new(null_value));
+ value
+ }
+ None => ScalarValue::try_from(DataType::Null)?,
+ },
+ _ => {
+ get_casted_value(get_scalar_value_from_args(args, 2)?,
out_data_type)?
+ }
+ };
Review Comment:
Thanks！Refactor the code as described above.
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