alamb commented on code in PR #11627:
URL: https://github.com/apache/datafusion/pull/11627#discussion_r1698999874
##########
datafusion/functions-aggregate/src/count.rs:
##########
@@ -433,6 +433,49 @@ impl GroupsAccumulator for CountGroupsAccumulator {
Ok(vec![Arc::new(counts) as ArrayRef])
}
+ fn convert_to_state(
+ &self,
+ values: &[ArrayRef],
+ opt_filter: Option<&BooleanArray>,
+ ) -> Result<Vec<ArrayRef>> {
+ let values = &values[0];
+
+ let state_array = match (values.logical_nulls(), opt_filter) {
+ (Some(nulls), None) => {
+ let mut builder = Int64Builder::with_capacity(values.len());
+ nulls
+ .into_iter()
+ .for_each(|is_valid| builder.append_value(is_valid as
i64));
+ builder.finish()
+ }
+ (Some(nulls), Some(filter)) => {
+ let mut builder = Int64Builder::with_capacity(values.len());
+ nulls.into_iter().zip(filter.iter()).for_each(
+ |(is_valid, filter_value)| {
+ builder.append_value(
Review Comment:
> I've rewritten state conversion for count on bitand on buffers + cast to
Int64 in the end, and according to benchmarks from the commit it got 20-25%
faster.
🎉
> Just a suggestion -- won't it be better to use BooleanBuffer + & (bitand
operator) instead of NullBuffer + union? NullBuffer is a bit confusing, so I've
"pulled" the logic from union right into state conversion function.
I think they are equivalent:
[`NullBuffer`](https://docs.rs/arrow/latest/arrow/buffer/struct.NullBuffer.html)
just wraps `BooleanBuffer` and `NullBuffer::union` just calls `&` underneath:
https://docs.rs/arrow-buffer/52.2.0/src/arrow_buffer/buffer/null.rs.html#76
(after replicating the `match(nulls, filter)` logic)
I don't have a strong opinion about which is more/less confusing
What I suggest we do is pull the logic to compute the output null mask basd
on the optional input nullmask and the optional filter into a function (like
`fn filtered_null_mask`) as it will be used in basically all of the
`convert_to_state` implementations. As long as it is well documented, I think
either implementation will work well
> Additionally, I plan to prepare benches and minimize ArrayBuilder usage
for min / max / sum during tomorrow.
Sounds good -- would you like to keep updating this PR or shall we merge
this PR and continue improvements with additional PRs on main?
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