Jimexist commented on a change in pull request #520:
URL: https://github.com/apache/arrow-datafusion/pull/520#discussion_r651356971
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File path: datafusion/src/physical_plan/expressions/nth_value.rs
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@@ -113,54 +111,32 @@ impl BuiltInWindowFunctionExpr for NthValue {
&self.name
}
- fn create_accumulator(&self) -> Result<Box<dyn WindowAccumulator>> {
- Ok(Box::new(NthValueAccumulator::try_new(
- self.kind,
- self.data_type.clone(),
- )?))
- }
-}
-
-#[derive(Debug)]
-struct NthValueAccumulator {
- kind: NthValueKind,
- offset: u32,
- value: ScalarValue,
-}
-
-impl NthValueAccumulator {
- /// new count accumulator
- pub fn try_new(kind: NthValueKind, data_type: DataType) -> Result<Self> {
- Ok(Self {
- kind,
- offset: 0,
- // null value of that data_type by default
- value: ScalarValue::try_from(&data_type)?,
- })
- }
-}
-
-impl WindowAccumulator for NthValueAccumulator {
- fn scan(&mut self, values: &[ScalarValue]) -> Result<Option<ScalarValue>> {
- self.offset += 1;
- match self.kind {
- NthValueKind::Last => {
- self.value = values[0].clone();
- }
- NthValueKind::First if self.offset == 1 => {
- self.value = values[0].clone();
- }
- NthValueKind::Nth(n) if self.offset == n => {
- self.value = values[0].clone();
- }
- _ => {}
+ fn evaluate(&self, num_rows: usize, values: &[ArrayRef]) ->
Result<ArrayRef> {
+ if values.is_empty() {
+ return Err(DataFusionError::Execution(format!(
+ "No arguments supplied to {}",
+ self.name()
+ )));
}
-
- Ok(None)
- }
-
- fn evaluate(&self) -> Result<Option<ScalarValue>> {
- Ok(Some(self.value.clone()))
+ let value = &values[0];
+ if value.len() != num_rows {
+ return Err(DataFusionError::Execution(format!(
+ "Invalid data supplied to {}, expect {} rows, got {} rows",
+ self.name(),
+ num_rows,
+ value.len()
+ )));
+ }
+ if num_rows == 0 {
Review comment:
this will be changed in later pull request
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