zhuqi-lucas commented on code in PR #16641:
URL: https://github.com/apache/datafusion/pull/16641#discussion_r2179165257
##########
datafusion/physical-optimizer/src/enforce_sorting/sort_pushdown.rs:
##########
@@ -668,6 +668,15 @@ fn handle_hash_join(
plan: &HashJoinExec,
parent_required: OrderingRequirements,
) -> Result<Option<Vec<Option<OrderingRequirements>>>> {
+ // Anti-joins (LeftAnti or RightAnti) do not preserve meaningful input
order,
+ // so sorting beforehand cannot be relied on. Bail out early for both
flavors:
+ match plan.join_type() {
+ JoinType::LeftAnti | JoinType::RightAnti => {
+ return Ok(None);
+ }
+ _ => {}
+ }
Review Comment:
But we support Topk(sort with limit) pushdown for hash join:
```rust
explain
SELECT *
FROM t1
LEFT ANTI JOIN t2 ON t1.k = t2.k
ORDER BY t1.k
LIMIT 2;
+---------------+------------------------------------------------------------+
| plan_type | plan
|
+---------------+------------------------------------------------------------+
| physical_plan | ┌───────────────────────────┐
|
| | │ SortPreservingMergeExec │
|
| | │ -------------------- │
|
| | │ k ASC NULLS LASTlimit: │
|
| | │ 2 │
|
| | └─────────────┬─────────────┘
|
| | ┌─────────────┴─────────────┐
|
| | │ CoalesceBatchesExec │
|
| | │ -------------------- │
|
| | │ limit: 2 │
|
| | │ │
|
| | │ target_batch_size: │
|
| | │ 8192 │
|
| | └─────────────┬─────────────┘
|
| | ┌─────────────┴─────────────┐
|
| | │ HashJoinExec │
|
| | │ -------------------- │
|
| | │ join_type: RightAnti ├──────────────┐
|
| | │ on: (k = k) │ │
|
| | └─────────────┬─────────────┘ │
|
| | ┌─────────────┴─────────────┐┌─────────────┴─────────────┐
|
| | │ DataSourceExec ││ SortExec(TopK) │
|
| | │ -------------------- ││ -------------------- │
|
| | │ bytes: 224 ││ k@0 ASC NULLS LAST │
|
| | │ format: memory ││ │
|
| | │ rows: 1 ││ limit: 2 │
|
| | └───────────────────────────┘└─────────────┬─────────────┘
|
| | ┌─────────────┴─────────────┐
|
| | │ RepartitionExec │
|
| | │ -------------------- │
|
| | │ partition_count(in->out): │
|
| | │ 1 -> 14 │
|
| | │ │
|
| | │ partitioning_scheme: │
|
| | │ RoundRobinBatch(14) │
|
| | └─────────────┬─────────────┘
|
| | ┌─────────────┴─────────────┐
|
| | │ DataSourceExec │
|
| | │ -------------------- │
|
| | │ bytes: 80384 │
|
| | │ format: memory │
|
| | │ rows: 2 │
|
| | └───────────────────────────┘
|
| |
|
+---------------+------------------------------------------------------------+
1 row(s) fetched.
Elapsed 0.002 seconds.
```
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