Rachelint commented on code in PR #11943:
URL: https://github.com/apache/datafusion/pull/11943#discussion_r1730379309
##########
datafusion/functions-aggregate-common/src/aggregate/groups_accumulator/prim_op.rs:
##########
@@ -92,32 +101,69 @@ where
opt_filter: Option<&BooleanArray>,
total_num_groups: usize,
) -> Result<()> {
+ if total_num_groups == 0 {
+ return Ok(());
+ }
+
assert_eq!(values.len(), 1, "single argument to update_batch");
let values = values[0].as_primitive::<T>();
- // update values
- self.values.resize(total_num_groups, self.starting_value);
-
// NullState dispatches / handles tracking nulls and groups that saw
no values
- self.null_state.accumulate(
- group_indices,
- values,
- opt_filter,
- total_num_groups,
- |group_index, new_value| {
- let value = &mut self.values[group_index];
- (self.prim_fn)(value, new_value);
- },
- );
+ match self.mode {
+ GroupStatesMode::Flat => {
+ // Ensure enough room in values
+ ensure_enough_room_for_flat_values(
+ &mut self.values_blocks,
+ total_num_groups,
+ self.starting_value,
+ );
+
+ let block = self.values_blocks.current_mut().unwrap();
+ self.null_state.accumulate_for_flat(
+ group_indices,
+ values,
+ opt_filter,
+ total_num_groups,
+ |group_index, new_value| {
+ let value = &mut block[group_index];
+ (self.prim_fn)(value, new_value);
+ },
+ );
+ }
+ GroupStatesMode::Blocked(blk_size) => {
Review Comment:
@alamb I try to merge the two mode(flat and blocked) into one this weekend.
But these two modes have the different parsing method for group index, if we
eliminate branches, we will need to use `trait object` or `function pointer` to
support this, and that will lead to dynamic dispatch for the row level
operation, and finally hurt the performance...
In my local
- q32 + static dispatch, 6800+ms
- q32 + dynmaic dispatch, 7100+ms
- q22(can't support blocked emission) + static dispatch, 1980+ms
- q22(can't support blocked emission) + static dispatch, 2050+ms
Is it ok to keep some branches for these two modes? like:
https://github.com/Rachelint/arrow-datafusion/blob/4fc0a27848bf490f2612a1525407aafe2743076d/datafusion/functions-aggregate/src/count.rs#L394-L418
What I am worried about is that this will lead to slight performance
regression although we disabled the new feature(like q22)...
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