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Posted to github@datafusion.apache.org by "jonathanc-n (via GitHub)" <gi...@apache.org> on 2025/06/11 21:17:51 UTC
[PR] POC: Reduce `Arc` cloning on hashmap build side [datafusion]
jonathanc-n opened a new pull request, #16380:
URL: https://github.com/apache/datafusion/pull/16380
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Re: [PR] POC: Reduce `Arc` cloning on hashmap build side [datafusion]
Posted by "jonathanc-n (via GitHub)" <gi...@apache.org>.
jonathanc-n commented on code in PR #16380:
URL: https://github.com/apache/datafusion/pull/16380#discussion_r2141135830
##########
datafusion/physical-plan/src/joins/hash_join.rs:
##########
@@ -95,9 +96,11 @@ struct JoinLeftData {
/// The hash table with indices into `batch`
hash_map: JoinHashMap,
/// The input rows for the build side
- batch: RecordBatch,
- /// The build side on expressions values
- values: Vec<ArrayRef>,
+ batch: Vec<RecordBatch>,
Review Comment:
@Dandandan Does this look like what you were looking for
##########
datafusion/physical-plan/src/joins/hash_join.rs:
##########
@@ -1372,15 +1407,16 @@ pub fn equal_rows_arr(
// The results are then folded (combined) using the and function to get a final equality result.
equal = iter
.map(|(left, right)| {
- let arr_left = take(left.as_ref(), indices_left, None)?;
+ let left_refs: Vec<&dyn Array> = left.iter().map(Arc::as_ref).collect();
+ let arr_left = interleave(&left_refs, indices_left)?;
let arr_right = take(right.as_ref(), indices_right, None)?;
eq_dyn_null(arr_left.as_ref(), arr_right.as_ref(), null_equals_null)
})
.try_fold(equal, |acc, equal2| and(&acc, &equal2?))?;
let filter_builder = FilterBuilder::new(&equal).optimize().build();
- let left_filtered = filter_builder.filter(indices_left)?;
+ let left_filtered = filter_builder.filter(indices_left)?; // annoying
Review Comment:
Currently this is a bit annoying, do you know how we can filter on this left indice (Vec<(usize, usize)>)@Dandandan
##########
datafusion/physical-plan/src/joins/utils.rs:
##########
@@ -850,6 +850,43 @@ pub(crate) fn apply_join_filter_to_indices(
))
}
+
+pub(crate) fn apply_join_filter_to_hash_indices(
Review Comment:
This is temporary new functions, just so I can test it out first by isolating it for hash joins.
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Re: [PR] POC: Reduce `Arc` cloning on hashmap build side [datafusion]
Posted by "jonathanc-n (via GitHub)" <gi...@apache.org>.
jonathanc-n commented on code in PR #16380:
URL: https://github.com/apache/datafusion/pull/16380#discussion_r2141169183
##########
datafusion/physical-plan/src/joins/hash_join.rs:
##########
@@ -1372,15 +1407,16 @@ pub fn equal_rows_arr(
// The results are then folded (combined) using the and function to get a final equality result.
equal = iter
.map(|(left, right)| {
- let arr_left = take(left.as_ref(), indices_left, None)?;
+ let left_refs: Vec<&dyn Array> = left.iter().map(Arc::as_ref).collect();
+ let arr_left = interleave(&left_refs, indices_left)?;
let arr_right = take(right.as_ref(), indices_right, None)?;
eq_dyn_null(arr_left.as_ref(), arr_right.as_ref(), null_equals_null)
})
.try_fold(equal, |acc, equal2| and(&acc, &equal2?))?;
let filter_builder = FilterBuilder::new(&equal).optimize().build();
- let left_filtered = filter_builder.filter(indices_left)?;
+ let left_filtered = filter_builder.filter(indices_left)?; // annoying
Review Comment:
```let mut left_filtered = Vec::with_capacity(equal.len());
for (i, &pair) in indices_left.iter().enumerate() {
if equal.value(i) {
left_filtered.push(pair);
}
}```
I currently did this for now, but it defeats the whole point of the mask
##########
datafusion/physical-plan/src/joins/hash_join.rs:
##########
@@ -1372,15 +1407,16 @@ pub fn equal_rows_arr(
// The results are then folded (combined) using the and function to get a final equality result.
equal = iter
.map(|(left, right)| {
- let arr_left = take(left.as_ref(), indices_left, None)?;
+ let left_refs: Vec<&dyn Array> = left.iter().map(Arc::as_ref).collect();
+ let arr_left = interleave(&left_refs, indices_left)?;
let arr_right = take(right.as_ref(), indices_right, None)?;
eq_dyn_null(arr_left.as_ref(), arr_right.as_ref(), null_equals_null)
})
.try_fold(equal, |acc, equal2| and(&acc, &equal2?))?;
let filter_builder = FilterBuilder::new(&equal).optimize().build();
- let left_filtered = filter_builder.filter(indices_left)?;
+ let left_filtered = filter_builder.filter(indices_left)?; // annoying
Review Comment:
```let mut left_filtered = Vec::with_capacity(equal.len());
for (i, &pair) in indices_left.iter().enumerate() {
if equal.value(i) {
left_filtered.push(pair);
}
}
```
I currently did this for now, but it defeats the whole point of the mask
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Re: [PR] POC: Reduce `Arc` cloning on hashmap build side [datafusion]
Posted by "Dandandan (via GitHub)" <gi...@apache.org>.
Dandandan commented on code in PR #16380:
URL: https://github.com/apache/datafusion/pull/16380#discussion_r2142059305
##########
datafusion/physical-plan/src/joins/hash_join.rs:
##########
@@ -991,52 +998,72 @@ async fn collect_left_input(
let mut hashmap = JoinHashMap::with_capacity(num_rows);
let mut hashes_buffer = Vec::new();
- let mut offset = 0;
// Updating hashmap starting from the last batch
let batches_iter = batches.iter().rev();
- for batch in batches_iter.clone() {
+ let mut batch_indices: Vec<(usize, usize)> = Vec::new();
+ let mut batch_row_total = usize::default();
+
+ for (batch_id, batch) in batches_iter.enumerate().clone() {
+ let batch_num_rows = batch.num_rows();
+
hashes_buffer.clear();
hashes_buffer.resize(batch.num_rows(), 0);
update_hash(
&on_left,
batch,
&mut hashmap,
- offset,
+ batch_row_total, // this is our offset
&random_state,
&mut hashes_buffer,
0,
true,
)?;
- offset += batch.num_rows();
+
+ for row_id in 0..batch_num_rows {
Review Comment:
this can use `extend`
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Re: [PR] POC: Reduce `Arc` cloning on hashmap build side [datafusion]
Posted by "jonathanc-n (via GitHub)" <gi...@apache.org>.
jonathanc-n commented on PR #16380:
URL: https://github.com/apache/datafusion/pull/16380#issuecomment-2964423579
I've noticed that it is possible for `interleave` to perform worse than `take` despite the `Arc` clones from `take`. This happens twice as well for `equal_row_arr` and `build_batch_from_indices`.
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Re: [PR] POC: Reduce `Arc` cloning on hashmap build side [datafusion]
Posted by "jonathanc-n (via GitHub)" <gi...@apache.org>.
jonathanc-n closed pull request #16380: POC: Reduce `Arc` cloning on hashmap build side
URL: https://github.com/apache/datafusion/pull/16380
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Re: [PR] POC: Reduce `Arc` cloning on hashmap build side [datafusion]
Posted by "Dandandan (via GitHub)" <gi...@apache.org>.
Dandandan commented on code in PR #16380:
URL: https://github.com/apache/datafusion/pull/16380#discussion_r2142058321
##########
datafusion/physical-plan/src/joins/hash_join.rs:
##########
@@ -95,9 +96,11 @@ struct JoinLeftData {
/// The hash table with indices into `batch`
hash_map: JoinHashMap,
/// The input rows for the build side
- batch: RecordBatch,
- /// The build side on expressions values
- values: Vec<ArrayRef>,
+ batch: Vec<RecordBatch>,
Review Comment:
Yeah this should be it, I think the tricky part of it might be to get it to equal performance.
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Re: [PR] POC: Reduce `Arc` cloning on hashmap build side [datafusion]
Posted by "jonathanc-n (via GitHub)" <gi...@apache.org>.
jonathanc-n commented on code in PR #16380:
URL: https://github.com/apache/datafusion/pull/16380#discussion_r2141169183
##########
datafusion/physical-plan/src/joins/hash_join.rs:
##########
@@ -1372,15 +1407,16 @@ pub fn equal_rows_arr(
// The results are then folded (combined) using the and function to get a final equality result.
equal = iter
.map(|(left, right)| {
- let arr_left = take(left.as_ref(), indices_left, None)?;
+ let left_refs: Vec<&dyn Array> = left.iter().map(Arc::as_ref).collect();
+ let arr_left = interleave(&left_refs, indices_left)?;
let arr_right = take(right.as_ref(), indices_right, None)?;
eq_dyn_null(arr_left.as_ref(), arr_right.as_ref(), null_equals_null)
})
.try_fold(equal, |acc, equal2| and(&acc, &equal2?))?;
let filter_builder = FilterBuilder::new(&equal).optimize().build();
- let left_filtered = filter_builder.filter(indices_left)?;
+ let left_filtered = filter_builder.filter(indices_left)?; // annoying
Review Comment:
```let mut left_filtered = Vec::with_capacity(equal.len());
for (i, &pair) in indices_left.iter().enumerate() {
if equal.value(i) {
left_filtered.push(pair);
}
}
```
I currently did this for now, but it defeats the whole point of the mask
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Re: [PR] POC: Reduce `Arc` cloning on hashmap build side [datafusion]
Posted by "Dandandan (via GitHub)" <gi...@apache.org>.
Dandandan commented on PR #16380:
URL: https://github.com/apache/datafusion/pull/16380#issuecomment-2969139729
> I've noticed that it is possible for `interleave` to perform worse than `take` despite the `Arc` clones from `take`. This happens twice as well for `equal_row_arr` and `build_batch_from_indices`.
Yes that will be the tricky part. We gain some speed during probing by concatenating the left side (which itself can be slow) into a singe batch.
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