neilconway opened a new pull request, #11770:
URL: https://github.com/apache/arrow-rs/pull/11770
# Which issue does this PR close?
- N/A
# Rationale for this change
When views are appended to an array that already has data buffers, the view
of each out-of-line string must have its buffer index increased by the number
of buffers already in the array. The obvious way to do this is to unpack the
view from a `u128` into a `ByteView`, update the `buffer_index` field, and
re-pack it. During the course of working on #11656, we found that it is
significantly faster to instead update the corresponding bits (64-95) in the
raw view directly, via shifting and addition.
This PR applies this optimization to two additional places:
`GenericByteViewBuilder::append_array`, which `concat` uses for string and
binary view arrays, and
`InProgressByteViewArray::append_views_and_update_buffer_index`, which is used
by `BatchCoalescer`.
# What changes are included in this PR?
See above. We also add a sanity-check that the output buffer count fits in
32 bits (which will always be true in practice; the previous behavior of
`GenericByteViewBuilder::append_array` was to silently truncate the buffer
count in this situation). We also improve the benchmarks for `concat` and
`coalesce_kernels`; those changes are sent as a separate PR in #11768.
# Benchmarks
(XXX Slightly out of date, will be replaced by new benchmark results
shortly...)
- AMD EPYC Milan (x86)
- coalesce_kernels, filter keeping 1% of rows
- single_utf8view, no nulls: 3.30 ms → 3.20 ms (−3.0%)
- single_utf8view (string_len=13..40), no nulls: 3.29 ms → 3.23 ms
(−2.0%) (runs 3% apart)
- single_binaryview, no nulls: 3.30 ms → 3.17 ms (−4.1%) (runs 6% apart)
- mixed_utf8view (max_string_len=20), no nulls: 1.78 ms → 1.73 ms (−2.6%)
- mixed_binaryview (max_string_len=20), no nulls: 1.86 ms → 1.81 ms
(−2.9%) (runs 7% apart)
- single_utf8view, 10% nulls: 4.93 ms → 4.80 ms (−2.8%)
- single_utf8view (string_len=13..40), 10% nulls: 5.05 ms → 4.89 ms
(−3.2%)
- single_binaryview, 10% nulls: 4.92 ms → 4.89 ms (−0.5%)
- mixed_utf8view (max_string_len=20), 10% nulls: 3.09 ms → 3.05 ms
(−1.3%)
- mixed_binaryview (max_string_len=20), 10% nulls: 3.08 ms → 3.06 ms
(−0.4%)
- coalesce_kernels, filter keeping 80% of rows
- single_utf8view, no nulls: 868.1 µs → 783.3 µs (−9.8%)
- single_utf8view (string_len=13..40), no nulls: 867.8 µs → 800.2 µs
(−7.8%) (runs 4% apart)
- single_binaryview, no nulls: 868.5 µs → 793.2 µs (−8.7%) (runs 2.9%
apart)
- mixed_utf8view (max_string_len=20), no nulls: 730.6 µs → 701.1 µs
(−4.0%)
- mixed_binaryview (max_string_len=20), no nulls: 1.50 ms → 1.50 ms
(+0.3%) (copies its strings, so doesn't reach the changed code)
- single_utf8view, 10% nulls: 1.01 ms → 922.8 µs (−8.7%)
- single_utf8view (string_len=13..40), 10% nulls: 1.02 ms → 949.7 µs
(−6.5%)
- single_binaryview, 10% nulls: 1.02 ms → 921.9 µs (−10.0%)
- mixed_utf8view (max_string_len=20), 10% nulls: 900.1 µs → 869.6 µs
(−3.4%)
- mixed_binaryview (max_string_len=20), 10% nulls: 895.8 µs → 873.1 µs
(−2.5%)
- coalesce_kernels, take of 80% of rows
- single_utf8view, no nulls: 824.6 µs → 757.0 µs (−8.2%) (runs 2.8%
apart)
- single_binaryview, no nulls: 830.5 µs → 737.2 µs (−11.2%) (runs 4%
apart)
- mixed_utf8view (max_string_len=20), no nulls: 563.8 µs → 515.6 µs
(−8.5%) (runs 2.4% apart)
- mixed_binaryview (max_string_len=20), no nulls: 1.43 ms → 1.43 ms
(+0.2%) (copies its strings, so doesn't reach the changed code)
- single_utf8view, 10% nulls: 1.17 ms → 1.06 ms (−10.2%) (runs 7% apart)
- single_binaryview, 10% nulls: 1.15 ms → 1.05 ms (−8.5%) (runs 4% apart)
- mixed_utf8view (max_string_len=20), 10% nulls: 924.3 µs → 885.9 µs
(−4.2%) (runs 3% apart)
- mixed_binaryview (max_string_len=20), 10% nulls: 919.9 µs → 906.8 µs
(−1.4%) (runs 6% apart)
- concat of 10 string view arrays of 8192 rows
- all_inline str_len=12, no nulls: 31.57 µs → 31.54 µs (−0.1%)
- str_len=20, no nulls: 74.88 µs → 48.63 µs (−35.1%)
- str_len=128, no nulls: 75.02 µs → 49.00 µs (−34.7%)
- mixed str_len=3..20, no nulls: 73.95 µs → 48.69 µs (−34.2%)
- all_inline str_len=12, 20% nulls: 32.44 µs → 32.39 µs (−0.2%)
- str_len=20, 20% nulls: 76.59 µs → 50.01 µs (−34.7%)
- str_len=128, 20% nulls: 76.39 µs → 49.99 µs (−34.6%)
- mixed str_len=3..20, 20% nulls: 75.54 µs → 49.92 µs (−33.9%) (runs 4%
apart)
- Apple M4 Max (ARM)
- coalesce_kernels, filter keeping 1% of rows
- single_utf8view, no nulls: 1.62 ms → 1.51 ms (−6.9%) (runs 4% apart)
- single_utf8view (string_len=13..40), no nulls: 1.62 ms → 1.54 ms
(−5.0%) (runs 4% apart)
- single_binaryview, no nulls: 1.57 ms → 1.48 ms (−5.7%) (runs 2.4%
apart)
- mixed_utf8view (max_string_len=20), no nulls: 1.08 ms → 1.04 ms (−3.3%)
- mixed_binaryview (max_string_len=20), no nulls: 1.12 ms → 1.05 ms
(−6.1%) (runs 5% apart)
- single_utf8view, 10% nulls: 2.44 ms → 2.43 ms (−0.3%) (runs 2.2% apart)
- single_utf8view (string_len=13..40), 10% nulls: 2.49 ms → 2.45 ms
(−1.4%) (runs 2.5% apart)
- single_binaryview, 10% nulls: 2.45 ms → 2.47 ms (+1.0%) (runs 6% apart)
- mixed_utf8view (max_string_len=20), 10% nulls: 2.61 ms → 2.54 ms
(−2.6%)
- mixed_binaryview (max_string_len=20), 10% nulls: 2.58 ms → 2.53 ms
(−2.2%)
- coalesce_kernels, filter keeping 80% of rows
- single_utf8view, no nulls: 562.9 µs → 519.8 µs (−7.7%)
- single_utf8view (string_len=13..40), no nulls: 562.7 µs → 520.0 µs
(−7.6%)
- single_binaryview, no nulls: 562.5 µs → 520.3 µs (−7.5%)
- mixed_utf8view (max_string_len=20), no nulls: 535.7 µs → 517.7 µs
(−3.4%)
- mixed_binaryview (max_string_len=20), no nulls: 1.10 ms → 1.11 ms
(+1.7%) (copies its strings, so doesn't reach the changed code)
- single_utf8view, 10% nulls: 618.9 µs → 578.6 µs (−6.5%)
- single_utf8view (string_len=13..40), 10% nulls: 617.9 µs → 574.5 µs
(−7.0%)
- single_binaryview, 10% nulls: 621.6 µs → 574.5 µs (−7.6%)
- mixed_utf8view (max_string_len=20), 10% nulls: 600.8 µs → 581.4 µs
(−3.2%)
- mixed_binaryview (max_string_len=20), 10% nulls: 602.1 µs → 581.4 µs
(−3.4%)
- coalesce_kernels, take of 80% of rows
- single_utf8view, no nulls: 458.1 µs → 397.7 µs (−13.2%)
- single_binaryview, no nulls: 448.5 µs → 389.3 µs (−13.2%) (runs 3.0%
apart)
- mixed_utf8view (max_string_len=20), no nulls: 311.2 µs → 290.2 µs
(−6.7%)
- mixed_binaryview (max_string_len=20), no nulls: 995.3 µs → 999.1 µs
(+0.4%) (copies its strings, so doesn't reach the changed code)
- single_utf8view, 10% nulls: 641.5 µs → 560.2 µs (−12.7%) (runs 4%
apart)
- single_binaryview, 10% nulls: 639.6 µs → 545.5 µs (−14.7%)
- mixed_utf8view (max_string_len=20), 10% nulls: 468.9 µs → 450.5 µs
(−3.9%)
- mixed_binaryview (max_string_len=20), 10% nulls: 470.5 µs → 448.9 µs
(−4.6%)
- concat of 10 string view arrays of 8192 rows
- all_inline str_len=12, no nulls: 15.67 µs → 15.61 µs (−0.4%)
- str_len=20, no nulls: 31.13 µs → 27.40 µs (−12.0%)
- str_len=128, no nulls: 31.20 µs → 27.55 µs (−11.7%)
- mixed str_len=3..20, no nulls: 30.80 µs → 27.24 µs (−11.6%)
- all_inline str_len=12, 20% nulls: 16.16 µs → 16.10 µs (−0.4%)
- str_len=20, 20% nulls: 31.77 µs → 28.10 µs (−11.5%)
- str_len=128, 20% nulls: 31.84 µs → 28.28 µs (−11.2%)
- mixed str_len=3..20, 20% nulls: 31.33 µs → 27.92 µs (−10.9%)
# Are these changes tested?
Covered by existing tests.
# Are there any significant user-facing changes?
Only in a corner case: if the output buffer count exceeds `u32::MAX`, we now
panic rather than silently truncating the count.
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