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perf: Speed up dt.offset_by 2x for constant durations #16728

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merged 5 commits into from
Jun 6, 2024
Merged

perf: Speed up dt.offset_by 2x for constant durations #16728

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559c3ac
speed up offset_by
MarcoGorelli Jun 4, 2024
f7c0cab
add extra tests
MarcoGorelli Jun 4, 2024
42cdc0f
try covering all changed lines
MarcoGorelli Jun 4, 2024
f6d31f8
simplify
MarcoGorelli Jun 5, 2024
42777b5
use wrapping_add_scalar
MarcoGorelli Jun 5, 2024
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72 changes: 41 additions & 31 deletions crates/polars-plan/src/dsl/function_expr/temporal.rs
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Original file line number Diff line number Diff line change
@@ -1,7 +1,7 @@
#[cfg(feature = "date_offset")]
use arrow::legacy::time_zone::Tz;
#[cfg(feature = "date_offset")]
use polars_core::chunked_array::ops::arity::try_binary_elementwise;
use polars_core::chunked_array::ops::arity::broadcast_try_binary_elementwise;
#[cfg(feature = "date_offset")]
use polars_time::prelude::*;

Expand Down Expand Up @@ -189,33 +189,52 @@ pub(super) fn datetime(
fn apply_offsets_to_datetime(
datetime: &Logical<DatetimeType, Int64Type>,
offsets: &StringChunked,
offset_fn: fn(&Duration, i64, Option<&Tz>) -> PolarsResult<i64>,
time_zone: Option<&Tz>,
) -> PolarsResult<Int64Chunked> {
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Just notice this now, but ideally the implementation should be in polars-ops or polars-time and then we only dispatch to those functions here. I'd like polars-plan to only be about the query planning/resolving.

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yup - ok if I do that separately?

match (datetime.len(), offsets.len()) {
(1, _) => match datetime.0.get(0) {
Some(dt) => offsets.try_apply_nonnull_values_generic(|offset| {
offset_fn(&Duration::parse(offset), dt, time_zone)
}),
_ => Ok(Int64Chunked::full_null(datetime.0.name(), offsets.len())),
},
(_, 1) => match offsets.get(0) {
match offsets.len() {
1 => match offsets.get(0) {
Some(offset) => {
let offset = &Duration::parse(offset);
datetime
.0
.try_apply_nonnull_values_generic(|v| offset_fn(offset, v, time_zone))
if offset.is_constant_duration(datetime.time_zone().as_deref()) {
// fastpath!
let mut duration = match datetime.time_unit() {
TimeUnit::Milliseconds => offset.duration_ms(),
TimeUnit::Microseconds => offset.duration_us(),
TimeUnit::Nanoseconds => offset.duration_ns(),
};
if offset.negative() {
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@ritchie46 ritchie46 Jun 5, 2024 •
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To reduce binary bloat, I think we can make one code branch of this that does the apply_values.

if offset.negative() {
   duration = - duration;
}

Ok(datetime.0.apply_values(|v| v + duration))

I think we can also use our already compiled kernels now. Which might also have more SIMD acceleration. If not, it at least saves compiler bloat.

// apply to inner and then you have to reconstruct the datetime.
datetime.0.clone().wrapping_add_scalar(duration);

duration = -duration;
}
Ok(datetime.0.clone().wrapping_add_scalar(duration))
} else {
let offset_fn = match datetime.time_unit() {
TimeUnit::Milliseconds => Duration::add_ms,
TimeUnit::Microseconds => Duration::add_us,
TimeUnit::Nanoseconds => Duration::add_ns,
};
datetime
.0
.try_apply_nonnull_values_generic(|v| offset_fn(offset, v, time_zone))
}
},
_ => Ok(datetime.0.apply(|_| None)),
},
_ => try_binary_elementwise(datetime, offsets, |timestamp_opt, offset_opt| {
match (timestamp_opt, offset_opt) {
_ => {
let offset_fn = match datetime.time_unit() {
TimeUnit::Milliseconds => Duration::add_ms,
TimeUnit::Microseconds => Duration::add_us,
TimeUnit::Nanoseconds => Duration::add_ns,
};
broadcast_try_binary_elementwise(datetime, offsets, |timestamp_opt, offset_opt| match (
timestamp_opt,
offset_opt,
) {
(Some(timestamp), Some(offset)) => {
offset_fn(&Duration::parse(offset), timestamp, time_zone).map(Some)
},
_ => Ok(None),
}
}),
})
},
}
}

Expand All @@ -231,7 +250,7 @@ pub(super) fn date_offset(s: &[Series]) -> PolarsResult<Series> {
.cast(&DataType::Datetime(TimeUnit::Milliseconds, None))
.unwrap();
let datetime = ts.datetime().unwrap();
let out = apply_offsets_to_datetime(datetime, offsets, Duration::add_ms, None)?;
let out = apply_offsets_to_datetime(datetime, offsets, None)?;
// sortedness is only guaranteed to be preserved if a constant offset is being added to every datetime
preserve_sortedness = match offsets.len() {
1 => offsets.get(0).is_some(),
Expand All @@ -244,21 +263,12 @@ pub(super) fn date_offset(s: &[Series]) -> PolarsResult<Series> {
DataType::Datetime(tu, tz) => {
let datetime = ts.datetime().unwrap();

let offset_fn = match tu {
TimeUnit::Nanoseconds => Duration::add_ns,
TimeUnit::Microseconds => Duration::add_us,
TimeUnit::Milliseconds => Duration::add_ms,
};

let out = match tz {
#[cfg(feature = "timezones")]
Some(ref tz) => apply_offsets_to_datetime(
datetime,
offsets,
offset_fn,
tz.parse::<Tz>().ok().as_ref(),
)?,
_ => apply_offsets_to_datetime(datetime, offsets, offset_fn, None)?,
Some(ref tz) => {
apply_offsets_to_datetime(datetime, offsets, tz.parse::<Tz>().ok().as_ref())?
},
_ => apply_offsets_to_datetime(datetime, offsets, None)?,
};
// Sortedness may not be preserved when crossing daylight savings time boundaries
// for calendar-aware durations.
Expand Down
114 changes: 114 additions & 0 deletions py-polars/tests/unit/operations/namespaces/temporal/test_offset_by.py
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Original file line number Diff line number Diff line change
@@ -0,0 +1,114 @@
from __future__ import annotations

from datetime import date, datetime
from typing import TYPE_CHECKING

import pytest

import polars as pl
from polars.testing import assert_series_equal

if TYPE_CHECKING:
from polars.type_aliases import TimeUnit


@pytest.mark.parametrize(
("inputs", "offset", "outputs"),
[
(
[date(2020, 1, 1), date(2020, 1, 2)],
"1d",
[date(2020, 1, 2), date(2020, 1, 3)],
),
(
[date(2020, 1, 1), date(2020, 1, 2)],
"-1d",
[date(2019, 12, 31), date(2020, 1, 1)],
),
(
[date(2020, 1, 1), date(2020, 1, 2)],
"3d",
[date(2020, 1, 4), date(2020, 1, 5)],
),
(
[date(2020, 1, 1), date(2020, 1, 2)],
"72h",
[date(2020, 1, 4), date(2020, 1, 5)],
),
(
[date(2020, 1, 1), date(2020, 1, 2)],
"2d24h",
[date(2020, 1, 4), date(2020, 1, 5)],
),
(
[date(2020, 1, 1), date(2020, 1, 2)],
"-2mo",
[date(2019, 11, 1), date(2019, 11, 2)],
),
],
)
def test_date_offset_by(inputs: list[date], offset: str, outputs: list[date]) -> None:
result = pl.Series(inputs).dt.offset_by(offset)
expected = pl.Series(outputs)
assert_series_equal(result, expected)


@pytest.mark.parametrize(
("inputs", "offset", "outputs"),
[
(
[date(2020, 1, 1), date(2020, 1, 2)],
"1d",
[date(2020, 1, 2), date(2020, 1, 3)],
),
(
[date(2020, 1, 1), date(2020, 1, 2)],
"-1d",
[date(2019, 12, 31), date(2020, 1, 1)],
),
(
[date(2020, 1, 1), date(2020, 1, 2)],
"3d",
[date(2020, 1, 4), date(2020, 1, 5)],
),
(
[date(2020, 1, 1), date(2020, 1, 2)],
"72h",
[date(2020, 1, 4), date(2020, 1, 5)],
),
(
[date(2020, 1, 1), date(2020, 1, 2)],
"2d24h",
[date(2020, 1, 4), date(2020, 1, 5)],
),
(
[date(2020, 1, 1), date(2020, 1, 2)],
"7m",
[datetime(2020, 1, 1, 0, 7), datetime(2020, 1, 2, 0, 7)],
),
(
[date(2020, 1, 1), date(2020, 1, 2)],
"-3m",
[datetime(2019, 12, 31, 23, 57), datetime(2020, 1, 1, 23, 57)],
),
(
[date(2020, 1, 1), date(2020, 1, 2)],
"2mo",
[datetime(2020, 3, 1), datetime(2020, 3, 2)],
),
],
)
@pytest.mark.parametrize("time_unit", ["ms", "us", "ns"])
@pytest.mark.parametrize("time_zone", ["Europe/London", "Asia/Kathmandu", None])
def test_datetime_offset_by(
inputs: list[date],
offset: str,
outputs: list[datetime],
time_unit: TimeUnit,
time_zone: str | None,
) -> None:
result = pl.Series(inputs, dtype=pl.Datetime(time_unit, time_zone)).dt.offset_by(
offset
)
expected = pl.Series(outputs, dtype=pl.Datetime(time_unit, time_zone))
assert_series_equal(result, expected)