peterxcli commented on code in PR #23854:
URL: https://github.com/apache/datafusion/pull/23854#discussion_r3748022493
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datafusion/physical-plan/src/joins/hash_join/shared_bounds.rs:
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@@ -656,38 +661,99 @@ impl SharedBuildAccumulator {
}
}
- let filter_expr = if has_canceled_unknown {
- let mut when_then_branches = empty_partition_ids
- .into_iter()
- .map(|partition_id| {
- (
- lit(ScalarValue::UInt64(Some(partition_id as
u64))),
- lit(false),
- )
- })
- .collect::<Vec<_>>();
- when_then_branches.extend(real_branches);
-
- if when_then_branches.is_empty() {
- lit(true)
- } else {
- Arc::new(CaseExpr::try_new(
- Some(modulo_expr),
- when_then_branches,
- Some(lit(true)),
- )?) as Arc<dyn PhysicalExpr>
- }
- } else if real_branches.is_empty() {
+ let filter_expr = if has_canceled_unknown
+ && real_partition_ids.is_empty()
+ && empty_partition_ids.is_empty()
+ {
+ lit(true)
+ } else if !has_canceled_unknown &&
real_partition_ids.is_empty() {
lit(false)
- } else if real_branches.len() == 1
+ } else if !has_canceled_unknown
+ && real_partition_ids.len() == 1
&& empty_partition_ids.len() + 1 == num_partitions
{
- Arc::clone(&real_branches[0].1)
+ Arc::clone(&partition_filters[real_partition_ids[0]])
+ } else if let Some(range_partitioning) =
&self.probe_range_partitioning {
+ // Range partitioning
+ assert_eq!(
+ partition_filters.len(),
+ range_partitioning.partition_count()
+ );
+ assert_eq!(self.on_right.len(),
range_partitioning.ordering().len());
+ let sort_exprs = self
+ .on_right
+ .iter()
+ .zip(range_partitioning.ordering())
+ .map(|(expr, sort_expr)| {
+ PhysicalSortExpr::new(Arc::clone(expr),
sort_expr.options)
+ })
+ .collect::<Vec<_>>();
+ let else_expr = partition_filters
+ .pop()
+ .expect("Range partitioning always has at least one
partition");
+ // CASE evaluates in order
+ //
+ // CASE
+ // WHEN key <range split[0] THEN F0
+ // WHEN key <range split[1] THEN F1
+ // ...
+ // ELSE Fn
+ // END
+ let when_then_expr = range_partitioning
+ .split_points()
+ .iter()
+ .zip(partition_filters)
+ .map(|(split_point, then_expr)| {
+ let when_expr = build_lexicographic_filter(
Review Comment:
Yes, a new expression would be easier than using `CASE WHEN key <
range_split[0] THEN F0 WHEN key < range_split[1] THEN F1 ... ELSE Fn END`.
There are a few similar discussions around this:
1. https://github.com/apache/datafusion/issues/23376#issuecomment-5025773266
2. https://github.com/apache/datafusion/issues/23376#issuecomment-5047433301
3. https://github.com/apache/datafusion/issues/23817#issuecomment-5139892005
The original idea behind using `WHEN key < range_split[0...n-2]` was to
avoid adding a new UDF, with the expectation that we could later optimize `CASE
WHEN` with a binary search on this kind of "monotonic function."
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