alamb commented on code in PR #21487:
URL: https://github.com/apache/datafusion/pull/21487#discussion_r3066186666
##########
datafusion/functions-aggregate/benches/first_last.rs:
##########
@@ -72,92 +74,129 @@ fn prepare_groups_accumulator(is_first: bool) -> Box<dyn
GroupsAccumulator> {
}
}
-fn prepare_accumulator(is_first: bool) -> Box<dyn Accumulator> {
- let schema = Arc::new(Schema::new(vec![
- Field::new("value", DataType::Int64, true),
- Field::new("ord", DataType::Int64, true),
- ]));
-
- let order_expr = col("ord", &schema).unwrap();
- let sort_expr = PhysicalSortExpr {
- expr: order_expr,
- options: SortOptions::default(),
- };
-
- let value_field: Arc<Field> = Field::new("value", DataType::Int64,
true).into();
- let accumulator_args = AccumulatorArgs {
- return_field: Arc::clone(&value_field),
- schema: &schema,
- expr_fields: &[value_field],
- ignore_nulls: false,
- order_bys: std::slice::from_ref(&sort_expr),
- is_reversed: false,
- name: if is_first {
- "FIRST_VALUE(value ORDER BY ord)"
- } else {
- "LAST_VALUE(value ORDER BY ord)"
- },
- is_distinct: false,
- exprs: &[col("value", &schema).unwrap()],
- };
-
+fn create_trivial_accumulator(
+ is_first: bool,
+ ignore_nulls: bool,
+) -> Box<dyn Accumulator> {
if is_first {
- FirstValue::new().accumulator(accumulator_args).unwrap()
+ Box::new(
+ TrivialFirstValueAccumulator::try_new(&DataType::Int64,
ignore_nulls)
+ .unwrap(),
+ )
} else {
- LastValue::new().accumulator(accumulator_args).unwrap()
+ Box::new(
+ TrivialLastValueAccumulator::try_new(&DataType::Int64,
ignore_nulls).unwrap(),
+ )
}
}
#[expect(clippy::needless_pass_by_value)]
-fn convert_to_state_bench(
+#[expect(clippy::too_many_arguments)]
+fn evaluate_bench(
c: &mut Criterion,
is_first: bool,
+ emit_to: EmitTo,
name: &str,
values: ArrayRef,
+ ord: ArrayRef,
opt_filter: Option<&BooleanArray>,
+ num_groups: usize,
) {
+ let n = values.len();
+ let group_indices: Vec<usize> = (0..n).map(|i| i % num_groups).collect();
+
c.bench_function(name, |b| {
- b.iter(|| {
- let accumulator = prepare_groups_accumulator(is_first);
- black_box(
- accumulator
- .convert_to_state(std::slice::from_ref(&values),
opt_filter)
- .unwrap(),
- )
+ b.iter_custom(|iters| {
+ // Every `evaluate` call mutates the accumulator, so prebuild
`iters` accumulators
+ let mut accumulators: Vec<Box<dyn GroupsAccumulator>> = (0..iters)
Review Comment:
Why are we creating more than one accumulator?
I think the important benchmark is a single accumuatlor and then merge
multiple batches per iteration. This seems like it merges one batch per
iteration across multiple accumulators?
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