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Posted to github@arrow.apache.org by "tustvold (via GitHub)" <gi...@apache.org> on 2023/04/06 17:00:23 UTC
[GitHub] [arrow-datafusion] tustvold opened a new pull request, #5897: Specialize Primitive Cursor
tustvold opened a new pull request, #5897:
URL: https://github.com/apache/arrow-datafusion/pull/5897
_Draft as builds on #5895_
# Which issue does this PR close?
<!--
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Part of #5882
# Rationale for this change
<!--
Why are you proposing this change? If this is already explained clearly in the issue then this section is not needed.
Explaining clearly why changes are proposed helps reviewers understand your changes and offer better suggestions for fixes.
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```
merge sorted i64 time: [5.3681 ms 5.3730 ms 5.3784 ms]
change: [-43.762% -43.690% -43.621%] (p = 0.00 < 0.05)
Performance has improved.
Found 4 outliers among 100 measurements (4.00%)
3 (3.00%) high mild
1 (1.00%) high severe
sort merge i64 time: [5.6187 ms 5.6264 ms 5.6344 ms]
change: [-42.354% -42.259% -42.162%] (p = 0.00 < 0.05)
Performance has improved.
Found 1 outliers among 100 measurements (1.00%)
1 (1.00%) high mild
merge sorted f64 time: [5.6240 ms 5.6307 ms 5.6386 ms]
change: [-40.730% -40.639% -40.548%] (p = 0.00 < 0.05)
Performance has improved.
Found 5 outliers among 100 measurements (5.00%)
3 (3.00%) high mild
2 (2.00%) high severe
sort merge f64 time: [5.9045 ms 5.9124 ms 5.9207 ms]
change: [-39.173% -39.065% -38.945%] (p = 0.00 < 0.05)
Performance has improved.
```
# What changes are included in this PR?
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# Are these changes tested?
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# Are there any user-facing changes?
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[GitHub] [arrow-datafusion] tustvold commented on a diff in pull request #5897: Specialize Primitive Cursor -- make sorts / merges on a single primitive column faster
Posted by "tustvold (via GitHub)" <gi...@apache.org>.
tustvold commented on code in PR #5897:
URL: https://github.com/apache/arrow-datafusion/pull/5897#discussion_r1162453846
##########
datafusion/core/src/physical_plan/sorts/cursor.rs:
##########
@@ -93,3 +96,232 @@ impl Cursor for RowCursor {
t
}
}
+
+/// A cursor over sorted, nullable [`ArrowNativeTypeOp`]
+///
+/// Note: comparing cursors with different `SortOptions` will yield an arbitrary ordering
+#[derive(Debug)]
+pub struct PrimitiveCursor<T: ArrowNativeTypeOp> {
+ values: ScalarBuffer<T>,
+ offset: usize,
+ // If nulls first, the first non-null index
+ // Otherwise, the first null index
+ null_threshold: usize,
+ options: SortOptions,
+}
+
+impl<T: ArrowNativeTypeOp> PrimitiveCursor<T> {
+ /// Create a new [`PrimitiveCursor`] from the provided `values` sorted according to `options`
+ pub fn new(options: SortOptions, values: ScalarBuffer<T>, null_count: usize) -> Self {
+ assert!(null_count <= values.len());
+
+ let null_threshold = match options.nulls_first {
+ true => null_count,
+ false => values.len() - null_count,
+ };
+
+ Self {
+ values,
+ offset: 0,
+ null_threshold,
+ options,
+ }
+ }
+
+ fn is_null(&self) -> bool {
+ (self.offset < self.null_threshold) == self.options.nulls_first
+ }
+
+ fn value(&self) -> T {
+ self.values[self.offset]
+ }
+}
+
+impl<T: ArrowNativeTypeOp> PartialEq for PrimitiveCursor<T> {
+ fn eq(&self, other: &Self) -> bool {
+ self.cmp(other).is_eq()
+ }
+}
+
+impl<T: ArrowNativeTypeOp> Eq for PrimitiveCursor<T> {}
+impl<T: ArrowNativeTypeOp> PartialOrd for PrimitiveCursor<T> {
+ fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
+ Some(self.cmp(other))
+ }
+}
+
+impl<T: ArrowNativeTypeOp> Ord for PrimitiveCursor<T> {
+ fn cmp(&self, other: &Self) -> Ordering {
+ match (self.is_null(), other.is_null()) {
+ (true, true) => Ordering::Equal,
+ (true, false) => match self.options.nulls_first {
+ true => Ordering::Less,
+ false => Ordering::Greater,
+ },
+ (false, true) => match self.options.nulls_first {
+ true => Ordering::Greater,
+ false => Ordering::Less,
+ },
+ (false, false) => {
+ let s_v = self.value();
+ let o_v = other.value();
+
+ match self.options.descending {
Review Comment:
It's definitely something we could experiment, my expectation is that it won't make a huge difference given how branch heavy merging inherently is
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[GitHub] [arrow-datafusion] tustvold commented on a diff in pull request #5897: Specialize Primitive Cursor -- make sorts / merges on a single primitive column faster
Posted by "tustvold (via GitHub)" <gi...@apache.org>.
tustvold commented on code in PR #5897:
URL: https://github.com/apache/arrow-datafusion/pull/5897#discussion_r1162452933
##########
datafusion/core/src/physical_plan/sorts/cursor.rs:
##########
@@ -93,3 +96,232 @@ impl Cursor for RowCursor {
t
}
}
+
+/// A cursor over sorted, nullable [`ArrowNativeTypeOp`]
+///
+/// Note: comparing cursors with different `SortOptions` will yield an arbitrary ordering
+#[derive(Debug)]
+pub struct PrimitiveCursor<T: ArrowNativeTypeOp> {
+ values: ScalarBuffer<T>,
+ offset: usize,
+ // If nulls first, the first non-null index
+ // Otherwise, the first null index
+ null_threshold: usize,
Review Comment:
I thought null_index might be confused for the index of the first null, which is not always the case
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[GitHub] [arrow-datafusion] alamb commented on a diff in pull request #5897: Specialize Primitive Cursor -- make sorts / merges on a single primitive column faster
Posted by "alamb (via GitHub)" <gi...@apache.org>.
alamb commented on code in PR #5897:
URL: https://github.com/apache/arrow-datafusion/pull/5897#discussion_r1162616186
##########
datafusion/core/src/physical_plan/sorts/cursor.rs:
##########
@@ -93,3 +96,232 @@ impl Cursor for RowCursor {
t
}
}
+
+/// A cursor over sorted, nullable [`ArrowNativeTypeOp`]
+///
+/// Note: comparing cursors with different `SortOptions` will yield an arbitrary ordering
+#[derive(Debug)]
+pub struct PrimitiveCursor<T: ArrowNativeTypeOp> {
+ values: ScalarBuffer<T>,
+ offset: usize,
+ // If nulls first, the first non-null index
+ // Otherwise, the first null index
+ null_threshold: usize,
Review Comment:
that makes sense.
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[GitHub] [arrow-datafusion] tustvold merged pull request #5897: Specialize Primitive Cursor -- make sorts / merges on a single primitive column faster
Posted by "tustvold (via GitHub)" <gi...@apache.org>.
tustvold merged PR #5897:
URL: https://github.com/apache/arrow-datafusion/pull/5897
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[GitHub] [arrow-datafusion] tustvold commented on a diff in pull request #5897: Specialize Primitive Cursor
Posted by "tustvold (via GitHub)" <gi...@apache.org>.
tustvold commented on code in PR #5897:
URL: https://github.com/apache/arrow-datafusion/pull/5897#discussion_r1160051954
##########
datafusion/core/Cargo.toml:
##########
@@ -57,6 +57,8 @@ unicode_expressions = ["datafusion-physical-expr/unicode_expressions", "datafusi
ahash = { version = "0.8", default-features = false, features = ["runtime-rng"] }
apache-avro = { version = "0.14", optional = true }
arrow = { workspace = true }
+arrow-schema = { workspace = true }
+arrow-array = { workspace = true }
Review Comment:
The downcast macros require these crates to be in scope
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[GitHub] [arrow-datafusion] ozankabak commented on pull request #5897: Specialize Primitive Cursor -- make sorts / merges on a single primitive column faster
Posted by "ozankabak (via GitHub)" <gi...@apache.org>.
ozankabak commented on PR #5897:
URL: https://github.com/apache/arrow-datafusion/pull/5897#issuecomment-1502140737
Thanks @tustvold
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[GitHub] [arrow-datafusion] tustvold commented on a diff in pull request #5897: Specialize Primitive Cursor
Posted by "tustvold (via GitHub)" <gi...@apache.org>.
tustvold commented on code in PR #5897:
URL: https://github.com/apache/arrow-datafusion/pull/5897#discussion_r1160051588
##########
datafusion/core/src/physical_plan/sorts/cursor.rs:
##########
@@ -93,3 +96,232 @@ impl Cursor for RowCursor {
t
}
}
+
+/// A cursor over sorted, nullable [`ArrowNativeTypeOp`]
+///
+/// Note: comparing cursors with different `SortOptions` will yield an arbitrary ordering
+#[derive(Debug)]
+pub struct PrimitiveCursor<T: ArrowNativeTypeOp> {
+ values: ScalarBuffer<T>,
+ offset: usize,
+ // If nulls first, the first non-null index
+ // Otherwise, the first null index
+ null_threshold: usize,
+ options: SortOptions,
+}
+
+impl<T: ArrowNativeTypeOp> PrimitiveCursor<T> {
Review Comment:
The astute will notice this is parameterised on the underlying Native type, helping to reduce codegen by not forcing SortPreservingMergeStream to be generic over ArrowPrimitiveType
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[GitHub] [arrow-datafusion] alamb commented on a diff in pull request #5897: Specialize Primitive Cursor -- make sorts / merges on a single column faster
Posted by "alamb (via GitHub)" <gi...@apache.org>.
alamb commented on code in PR #5897:
URL: https://github.com/apache/arrow-datafusion/pull/5897#discussion_r1161935087
##########
datafusion/core/src/physical_plan/sorts/merge.rs:
##########
@@ -37,8 +52,16 @@ pub(crate) fn streaming_merge(
tracking_metrics: MemTrackingMetrics,
batch_size: usize,
) -> Result<SendableRecordBatchStream> {
- let streams = RowCursorStream::try_new(schema.as_ref(), expressions, streams)?;
+ if expressions.len() == 1 {
Review Comment:
I think it is worth a comment here explaining the rationale for this for future readers. Something like
```suggestion
// special case single column primitives to avoid overhead of runtime comparators
if expressions.len() == 1 {
```
##########
datafusion/core/src/physical_plan/sorts/cursor.rs:
##########
@@ -93,3 +96,232 @@ impl Cursor for RowCursor {
t
}
}
+
+/// A cursor over sorted, nullable [`ArrowNativeTypeOp`]
+///
+/// Note: comparing cursors with different `SortOptions` will yield an arbitrary ordering
+#[derive(Debug)]
+pub struct PrimitiveCursor<T: ArrowNativeTypeOp> {
+ values: ScalarBuffer<T>,
+ offset: usize,
+ // If nulls first, the first non-null index
+ // Otherwise, the first null index
+ null_threshold: usize,
+ options: SortOptions,
+}
+
+impl<T: ArrowNativeTypeOp> PrimitiveCursor<T> {
+ /// Create a new [`PrimitiveCursor`] from the provided `values` sorted according to `options`
+ pub fn new(options: SortOptions, values: ScalarBuffer<T>, null_count: usize) -> Self {
+ assert!(null_count <= values.len());
+
+ let null_threshold = match options.nulls_first {
+ true => null_count,
+ false => values.len() - null_count,
+ };
+
+ Self {
+ values,
+ offset: 0,
+ null_threshold,
+ options,
+ }
+ }
+
+ fn is_null(&self) -> bool {
+ (self.offset < self.null_threshold) == self.options.nulls_first
+ }
+
+ fn value(&self) -> T {
+ self.values[self.offset]
+ }
+}
+
+impl<T: ArrowNativeTypeOp> PartialEq for PrimitiveCursor<T> {
+ fn eq(&self, other: &Self) -> bool {
+ self.cmp(other).is_eq()
+ }
+}
+
+impl<T: ArrowNativeTypeOp> Eq for PrimitiveCursor<T> {}
+impl<T: ArrowNativeTypeOp> PartialOrd for PrimitiveCursor<T> {
+ fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
+ Some(self.cmp(other))
+ }
+}
+
+impl<T: ArrowNativeTypeOp> Ord for PrimitiveCursor<T> {
+ fn cmp(&self, other: &Self) -> Ordering {
+ match (self.is_null(), other.is_null()) {
+ (true, true) => Ordering::Equal,
+ (true, false) => match self.options.nulls_first {
+ true => Ordering::Less,
+ false => Ordering::Greater,
+ },
+ (false, true) => match self.options.nulls_first {
+ true => Ordering::Greater,
+ false => Ordering::Less,
+ },
+ (false, false) => {
+ let s_v = self.value();
+ let o_v = other.value();
+
+ match self.options.descending {
Review Comment:
I wonder if it would be worth specializing on consts `NULLS_FIRST` and `ASC/DESC` as well to avoid what looks like runtime overhead in the hot path.
Maybe it doesn't make any practical difference
##########
datafusion/core/src/physical_plan/sorts/stream.rs:
##########
@@ -139,3 +142,67 @@ impl PartitionedStream for RowCursorStream {
}))
}
}
+
+pub struct PrimitiveCursorStream<T: ArrowPrimitiveType> {
Review Comment:
```suggestion
/// Specialized stream for sorts on single primitive columns
pub struct PrimitiveCursorStream<T: ArrowPrimitiveType> {
```
##########
datafusion/core/src/physical_plan/sorts/cursor.rs:
##########
@@ -93,3 +96,232 @@ impl Cursor for RowCursor {
t
}
}
+
+/// A cursor over sorted, nullable [`ArrowNativeTypeOp`]
+///
+/// Note: comparing cursors with different `SortOptions` will yield an arbitrary ordering
+#[derive(Debug)]
+pub struct PrimitiveCursor<T: ArrowNativeTypeOp> {
+ values: ScalarBuffer<T>,
+ offset: usize,
+ // If nulls first, the first non-null index
+ // Otherwise, the first null index
+ null_threshold: usize,
Review Comment:
Is there any reason it is called `null_threshold` rather than `null_index` given it is a null index 🤔
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[GitHub] [arrow-datafusion] tustvold commented on a diff in pull request #5897: Specialize Primitive Cursor
Posted by "tustvold (via GitHub)" <gi...@apache.org>.
tustvold commented on code in PR #5897:
URL: https://github.com/apache/arrow-datafusion/pull/5897#discussion_r1160050921
##########
datafusion/core/src/physical_plan/sorts/cursor.rs:
##########
@@ -93,3 +96,232 @@ impl Cursor for RowCursor {
t
}
}
+
+/// A cursor over sorted, nullable [`ArrowNativeTypeOp`]
+///
+/// Note: comparing cursors with different `SortOptions` will yield an arbitrary ordering
+#[derive(Debug)]
+pub struct PrimitiveCursor<T: ArrowNativeTypeOp> {
+ values: ScalarBuffer<T>,
+ offset: usize,
+ // If nulls first, the first non-null index
+ // Otherwise, the first null index
+ null_threshold: usize,
Review Comment:
I'm quite pleased with this formulation of nulls, it avoids needing to consult the null mask at all :smile:
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