lidavidm commented on a change in pull request #12080:
URL: https://github.com/apache/arrow/pull/12080#discussion_r813887878
##########
File path: cpp/src/arrow/compute/exec.cc
##########
@@ -772,14 +769,27 @@ class ScalarExecutor : public
KernelExecutorImpl<ScalarKernel> {
return Status::OK();
}
- Status SetupPreallocation(int64_t total_length) {
+ Status SetupPreallocation(int64_t total_length, const std::vector<Datum>&
args) {
output_num_buffers_ =
static_cast<int>(output_descr_.type->layout().buffers.size());
-
- // Decide if we need to preallocate memory for this kernel
- validity_preallocated_ =
- (kernel_->null_handling != NullHandling::COMPUTED_NO_PREALLOCATE &&
- kernel_->null_handling != NullHandling::OUTPUT_NOT_NULL &&
- output_descr_.type->id() != Type::NA);
+ auto out_type_id = output_descr_.type->id();
+ // Default to no validity pre-allocation for following cases:
+ // - Output Array is NullArray
+ // - kernel_->null_handling is COMPUTED_NO_PREALLOCATE or OUTPUT_NOT_NULL
+ validity_preallocated_ = false;
+ if (out_type_id != Type::NA) {
+ if (kernel_->null_handling == NullHandling::COMPUTED_PREALLOCATE) {
+ // Override the flag if kernel asks for pre-allocation
+ validity_preallocated_ = true;
+ } else if (kernel_->null_handling == NullHandling::INTERSECTION) {
+ bool are_all_inputs_valid = true;
+ for (auto& arg : args) {
+ auto null_gen = NullGeneralization::Get(arg) ==
NullGeneralization::ALL_VALID;
+ are_all_inputs_valid = are_all_inputs_valid && null_gen;
+ }
+ validity_preallocated_ =
+ !(are_all_inputs_valid || kernel_->can_write_into_slices);
Review comment:
Why does `can_write_into_slices` disable preallocation?
##########
File path: cpp/src/arrow/compute/exec.cc
##########
@@ -792,7 +802,7 @@ class ScalarExecutor : public
KernelExecutorImpl<ScalarKernel> {
preallocate_contiguous_ =
(exec_context()->preallocate_contiguous() &&
kernel_->can_write_into_slices &&
validity_preallocated_ && !is_nested(output_descr_.type->id()) &&
- !is_dictionary(output_descr_.type->id()) &&
+ !is_dictionary(out_type_id) &&
Review comment:
nit: if we're going to update this here, also update the usage of
`output_descr_.type->id()` on the previous line?
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