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perf: Improve DataFrame.sort().limit/top_k performance #19731

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merged 4 commits into from
Nov 11, 2024
Merged

perf: Improve DataFrame.sort().limit/top_k performance #19731

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c987243
perf: Improve `DataFrame.sort().limit` performance
ritchie46 Nov 11, 2024
134e249
perf: Improve `DataFrame.sort().limit` performance
ritchie46 Nov 11, 2024
5d83109
lint
ritchie46 Nov 11, 2024
632509b
fix
ritchie46 Nov 11, 2024
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5 changes: 5 additions & 0 deletions crates/polars-core/src/chunked_array/ops/sort/arg_bottom_k.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -39,6 +39,11 @@ pub fn _arg_bottom_k(
_broadcast_bools(by_column.len(), &mut sort_options.descending);
_broadcast_bools(by_column.len(), &mut sort_options.nulls_last);

// Don't go into row encoding.
if by_column.len() == 1 && sort_options.limit.is_some() && !sort_options.maintain_order {
return Ok(NoNull::new(by_column[0].arg_sort((&*sort_options).into())));
}

let encoded = _get_rows_encoded(
by_column,
&sort_options.descending,
Expand Down
64 changes: 58 additions & 6 deletions crates/polars-core/src/chunked_array/ops/sort/arg_sort.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -18,7 +18,7 @@ pub(super) fn arg_sort<I, J, T>(
iters: I,
options: SortOptions,
null_count: usize,
len: usize,
mut len: usize,
) -> IdxCa
where
I: IntoIterator<Item = J>,
Expand Down Expand Up @@ -49,14 +49,46 @@ where
vals.extend(iter);
}

sort_impl(vals.as_mut_slice(), options);
let vals = if let Some((limit, desc)) = options.limit {
let limit = limit as usize;
// Overwrite output len.
len = limit;
let out = if limit >= vals.len() {
vals.as_mut_slice()
} else if desc {
let (lower, _el, _upper) = vals
.as_mut_slice()
.select_nth_unstable_by(limit, |a, b| b.1.tot_cmp(&a.1));
lower
} else {
let (lower, _el, _upper) = vals
.as_mut_slice()
.select_nth_unstable_by(limit, |a, b| a.1.tot_cmp(&b.1));
lower
};

sort_impl(out, options);
out
} else {
sort_impl(vals.as_mut_slice(), options);
vals.as_slice()
};

let iter = vals.into_iter().map(|(idx, _v)| idx);
let iter = vals.iter().map(|(idx, _v)| idx).copied();
let idx = if nulls_last {
let mut idx = Vec::with_capacity(len);
idx.extend(iter);
idx.extend(nulls_idx);

let nulls_idx = if options.limit.is_some() {
&nulls_idx[..len - idx.len()]
} else {
&nulls_idx
};
idx.extend_from_slice(nulls_idx);
idx
} else if options.limit.is_some() {
nulls_idx.extend(iter.take(len - nulls_idx.len()));
nulls_idx
} else {
let ptr = nulls_idx.as_ptr() as usize;
nulls_idx.extend(iter);
Expand Down Expand Up @@ -90,9 +122,29 @@ where
}));
}

sort_impl(vals.as_mut_slice(), options);
let vals = if let Some((limit, desc)) = options.limit {
let limit = limit as usize;
let out = if limit >= vals.len() {
vals.as_mut_slice()
} else if desc {
let (lower, _el, _upper) = vals
.as_mut_slice()
.select_nth_unstable_by(limit, |a, b| b.1.tot_cmp(&a.1));
lower
} else {
let (lower, _el, _upper) = vals
.as_mut_slice()
.select_nth_unstable_by(limit, |a, b| a.1.tot_cmp(&b.1));
lower
};
sort_impl(out, options);
out
} else {
sort_impl(vals.as_mut_slice(), options);
vals.as_slice()
};

let iter = vals.into_iter().map(|(idx, _v)| idx);
let iter = vals.iter().map(|(idx, _v)| idx).copied();
let idx: Vec<_> = iter.collect_trusted();

ChunkedArray::with_chunk(name, IdxArr::from_data_default(Buffer::from(idx), None))
Expand Down
1 change: 1 addition & 0 deletions crates/polars-core/src/chunked_array/ops/sort/categorical.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -53,6 +53,7 @@ impl CategoricalChunked {
descending,
multithreaded: true,
maintain_order: false,
limit: None,
})
}

Expand Down
10 changes: 10 additions & 0 deletions crates/polars-core/src/chunked_array/ops/sort/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -335,6 +335,7 @@ impl ChunkSort<StringType> for StringChunked {
nulls_last: false,
multithreaded: true,
maintain_order: false,
limit: None,
})
}

Expand Down Expand Up @@ -406,6 +407,7 @@ impl ChunkSort<BinaryType> for BinaryChunked {
nulls_last: false,
multithreaded: true,
maintain_order: false,
limit: None,
})
}

Expand Down Expand Up @@ -536,6 +538,7 @@ impl ChunkSort<BinaryOffsetType> for BinaryOffsetChunked {
nulls_last: false,
multithreaded: true,
maintain_order: false,
limit: None,
})
}

Expand Down Expand Up @@ -672,6 +675,7 @@ impl ChunkSort<BooleanType> for BooleanChunked {
nulls_last: false,
multithreaded: true,
maintain_order: false,
limit: None,
})
}

Expand Down Expand Up @@ -797,6 +801,7 @@ mod test {
nulls_last: false,
multithreaded: true,
maintain_order: false,
limit: None,
});
assert_eq!(
Vec::from(&out),
Expand All @@ -816,6 +821,7 @@ mod test {
nulls_last: true,
multithreaded: true,
maintain_order: false,
limit: None,
});
assert_eq!(
Vec::from(&out),
Expand Down Expand Up @@ -925,6 +931,7 @@ mod test {
nulls_last: false,
multithreaded: true,
maintain_order: false,
limit: None,
});
let expected = &[None, None, Some("a"), Some("b"), Some("c")];
assert_eq!(Vec::from(&out), expected);
Expand All @@ -934,6 +941,7 @@ mod test {
nulls_last: false,
multithreaded: true,
maintain_order: false,
limit: None,
});

let expected = &[None, None, Some("c"), Some("b"), Some("a")];
Expand All @@ -944,6 +952,7 @@ mod test {
nulls_last: true,
multithreaded: true,
maintain_order: false,
limit: None,
});
let expected = &[Some("a"), Some("b"), Some("c"), None, None];
assert_eq!(Vec::from(&out), expected);
Expand All @@ -953,6 +962,7 @@ mod test {
nulls_last: true,
multithreaded: true,
maintain_order: false,
limit: None,
});
let expected = &[Some("c"), Some("b"), Some("a"), None, None];
assert_eq!(Vec::from(&out), expected);
Expand Down
12 changes: 12 additions & 0 deletions crates/polars-core/src/chunked_array/ops/sort/options.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -41,6 +41,10 @@ pub struct SortOptions {
/// If true maintain the order of equal elements.
/// Default `false`.
pub maintain_order: bool,
/// Limit a sort output, this is for optimization purposes and might be ignored.
/// - Len
/// - Descending
pub limit: Option<(IdxSize, bool)>,
}

/// Sort options for multi-series sorting.
Expand Down Expand Up @@ -96,6 +100,10 @@ pub struct SortMultipleOptions {
pub multithreaded: bool,
/// Whether maintain the order of equal elements. Default `false`.
pub maintain_order: bool,
/// Limit a sort output, this is for optimization purposes and might be ignored.
/// - Len
/// - Descending
pub limit: Option<(IdxSize, bool)>,
}

impl Default for SortOptions {
Expand All @@ -105,6 +113,7 @@ impl Default for SortOptions {
nulls_last: false,
multithreaded: true,
maintain_order: false,
limit: None,
}
}
}
Expand All @@ -116,6 +125,7 @@ impl Default for SortMultipleOptions {
nulls_last: vec![false],
multithreaded: true,
maintain_order: false,
limit: None,
}
}
}
Expand Down Expand Up @@ -224,6 +234,7 @@ impl From<&SortOptions> for SortMultipleOptions {
nulls_last: vec![value.nulls_last],
multithreaded: value.multithreaded,
maintain_order: value.maintain_order,
limit: value.limit,
}
}
}
Expand All @@ -235,6 +246,7 @@ impl From<&SortMultipleOptions> for SortOptions {
nulls_last: value.nulls_last.first().copied().unwrap_or(false),
multithreaded: value.multithreaded,
maintain_order: value.maintain_order,
limit: value.limit,
}
}
}
7 changes: 7 additions & 0 deletions crates/polars-core/src/frame/mod.rs
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Expand Up @@ -1989,6 +1989,12 @@ impl DataFrame {
return Ok(out);
}
if let Some((0, k)) = slice {
let desc = if sort_options.descending.len() == 1 {
sort_options.descending[0]
} else {
false
};
sort_options.limit = Some((k as IdxSize, desc));
return self.bottom_k_impl(k, by_column, sort_options);
}

Expand All @@ -2012,6 +2018,7 @@ impl DataFrame {
nulls_last: sort_options.nulls_last[0],
multithreaded: sort_options.multithreaded,
maintain_order: sort_options.maintain_order,
limit: sort_options.limit,
};
// fast path for a frame with a single series
// no need to compute the sort indices and then take by these indices
Expand Down
2 changes: 2 additions & 0 deletions crates/polars-expr/src/expressions/sortby.rs
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Expand Up @@ -160,6 +160,7 @@ fn sort_by_groups_multiple_by(
nulls_last: nulls_last.to_owned(),
multithreaded,
maintain_order,
limit: None,
};

let sorted_idx = groups[0]
Expand All @@ -180,6 +181,7 @@ fn sort_by_groups_multiple_by(
nulls_last: nulls_last.to_owned(),
multithreaded,
maintain_order,
limit: None,
};
let sorted_idx = groups[0]
.as_materialized_series()
Expand Down
5 changes: 5 additions & 0 deletions crates/polars-lazy/src/tests/aggregations.rs
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Expand Up @@ -450,6 +450,7 @@ fn take_aggregations() -> PolarsResult<()> {
nulls_last: false,
multithreaded: true,
maintain_order: false,
limit: None,
})
.head(Some(2)),
)
Expand Down Expand Up @@ -489,6 +490,7 @@ fn test_take_consistency() -> PolarsResult<()> {
nulls_last: false,
multithreaded: true,
maintain_order: false,
limit: None,
})
.get(lit(0))])
.collect()?;
Expand All @@ -507,6 +509,7 @@ fn test_take_consistency() -> PolarsResult<()> {
nulls_last: false,
multithreaded: true,
maintain_order: false,
limit: None,
})
.get(lit(0))])
.collect()?;
Expand All @@ -526,6 +529,7 @@ fn test_take_consistency() -> PolarsResult<()> {
nulls_last: false,
multithreaded: true,
maintain_order: false,
limit: None,
})
.get(lit(0))
.alias("1"),
Expand All @@ -537,6 +541,7 @@ fn test_take_consistency() -> PolarsResult<()> {
nulls_last: false,
multithreaded: true,
maintain_order: false,
limit: None,
})
.get(lit(0)),
)
Expand Down
1 change: 1 addition & 0 deletions crates/polars-lazy/src/tests/queries.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1666,6 +1666,7 @@ fn test_single_group_result() -> PolarsResult<()> {
nulls_last: false,
multithreaded: true,
maintain_order: false,
limit: None,
})
.over([col("a")])])
.collect()?;
Expand Down
1 change: 1 addition & 0 deletions crates/polars-ops/src/chunked_array/top_k.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -285,6 +285,7 @@ fn top_k_by_impl(
nulls_last: vec![true; by.len()],
multithreaded,
maintain_order: false,
limit: None,
};

let idx = _arg_bottom_k(k, by, &mut sort_options)?;
Expand Down
3 changes: 3 additions & 0 deletions crates/polars-ops/src/frame/join/hash_join/sort_merge.rs
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Expand Up @@ -225,6 +225,7 @@ pub(crate) fn _sort_or_hash_inner(
nulls_last: false,
multithreaded: true,
maintain_order: false,
limit: None,
});
let s_right = unsafe { s_right.take_unchecked(&sort_idx) };
let ids = par_sorted_merge_inner_no_nulls(s_left, &s_right);
Expand Down Expand Up @@ -252,6 +253,7 @@ pub(crate) fn _sort_or_hash_inner(
nulls_last: false,
multithreaded: true,
maintain_order: false,
limit: None,
});
let s_left = unsafe { s_left.take_unchecked(&sort_idx) };
let ids = par_sorted_merge_inner_no_nulls(&s_left, s_right);
Expand Down Expand Up @@ -323,6 +325,7 @@ pub(crate) fn sort_or_hash_left(
nulls_last: false,
multithreaded: true,
maintain_order: false,
limit: None,
});
let s_right = unsafe { s_right.take_unchecked(&sort_idx) };

Expand Down
2 changes: 2 additions & 0 deletions crates/polars-pipe/src/executors/sinks/sort/source.rs
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Expand Up @@ -101,6 +101,7 @@ impl SortSource {
nulls_last: self.nulls_last,
multithreaded: true,
maintain_order: false,
limit: None,
},
),
Some((offset, len)) => {
Expand All @@ -119,6 +120,7 @@ impl SortSource {
nulls_last: self.nulls_last,
multithreaded: true,
maintain_order: false,
limit: None,
},
);
*len = len.saturating_sub(df_len);
Expand Down
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