ARROW-10837: [Rust][DataFusion] Use `Vec<u8>` for hash keys by Dandandan · Pull Request #8863 · apache/arrow

Dandandan · 2020-12-07T18:34:34Z

This PR is a follow up of #8765 . Here, the hashmap values for the key are converted to Vec<u8> to use as key instead.

This is a bit faster as both hashing and cloning will be faster. It will also use less additional memory than the earlier usage of the dynamic GroupByScalar values (for hash join).

[This PR]

Query 12 iteration 0 took 1315 ms
Query 12 iteration 1 took 1324 ms
Query 12 iteration 2 took 1329 ms
Query 12 iteration 3 took 1334 ms
Query 12 iteration 4 took 1335 ms
Query 12 iteration 5 took 1338 ms
Query 12 iteration 6 took 1337 ms
Query 12 iteration 7 took 1349 ms
Query 12 iteration 8 took 1348 ms
Query 12 iteration 9 took 1358 ms

[Master]

Query 12 iteration 0 took 1379 ms
Query 12 iteration 1 took 1383 ms
Query 12 iteration 2 took 1401 ms
Query 12 iteration 3 took 1406 ms
Query 12 iteration 4 took 1420 ms
Query 12 iteration 5 took 1435 ms
Query 12 iteration 6 took 1401 ms
Query 12 iteration 7 took 1404 ms
Query 12 iteration 8 took 1418 ms
Query 12 iteration 9 took 1416 ms

[This PR]

Query 1 iteration 0 took 871 ms
Query 1 iteration 1 took 866 ms
Query 1 iteration 2 took 869 ms
Query 1 iteration 3 took 869 ms
Query 1 iteration 4 took 867 ms
Query 1 iteration 5 took 874 ms
Query 1 iteration 6 took 870 ms
Query 1 iteration 7 took 875 ms
Query 1 iteration 8 took 871 ms
Query 1 iteration 9 took 869 ms

[Master]

Query 1 iteration 0 took 1189 ms
Query 1 iteration 1 took 1192 ms
Query 1 iteration 2 took 1189 ms
Query 1 iteration 3 took 1185 ms
Query 1 iteration 4 took 1193 ms
Query 1 iteration 5 took 1202 ms
Query 1 iteration 6 took 1547 ms
Query 1 iteration 7 took 1242 ms
Query 1 iteration 8 took 1202 ms
Query 1 iteration 9 took 1197 ms

FWIW, micro benchmark results for aggregate queries:

aggregate_query_no_group_by 15 12 time: [538.54 us 541.48 us 544.74 us]
change: [+5.4384% +6.6260% +8.2034%] (p = 0.00 < 0.05)
Performance has regressed.
Found 8 outliers among 100 measurements (8.00%)
7 (7.00%) high mild
1 (1.00%) high severe
aggregate_query_no_group_by_count_distinct_wide 15 12 time: [4.8418 ms 4.8744 ms 4.9076 ms]
change: [-13.890% -12.580% -11.260%] (p = 0.00 < 0.05)
Performance has improved.
aggregate_query_no_group_by_count_distinct_narrow 15 12 time: [2.1910 ms 2.2100 ms 2.2291 ms]
change: [-30.490% -28.886% -27.271%] (p = 0.00 < 0.05)
Performance has improved.
Benchmarking aggregate_query_group_by 15 12: Warming up for 3.0000 s
Warning: Unable to complete 100 samples in 5.0s. You may wish to increase target time to 8.1s, enable flat sampling, or reduce sample count to 50.
aggregate_query_group_by 15 12 time: [1.5905 ms 1.5977 ms 1.6054 ms]
change: [-18.271% -16.780% -15.396%] (p = 0.00 < 0.05)
Performance has improved.
Found 6 outliers among 100 measurements (6.00%)
1 (1.00%) high mild
5 (5.00%) high severe
aggregate_query_group_by_with_filter 15 12 time: [788.26 us 792.05 us 795.74 us]
change: [-9.8088% -8.5606% -7.4141%] (p = 0.00 < 0.05)
Performance has improved.
Found 6 outliers among 100 measurements (6.00%)
5 (5.00%) high mild
1 (1.00%) high severe
Benchmarking aggregate_query_group_by_u64 15 12: Warming up for 3.0000 s
Warning: Unable to complete 100 samples in 5.0s. You may wish to increase target time to 9.3s, enable flat sampling, or reduce sample count to 50.
aggregate_query_group_by_u64 15 12 time: [1.8502 ms 1.8565 ms 1.8630 ms]
change: [+8.6203% +9.8872% +10.973%] (p = 0.00 < 0.05)
Performance has regressed.
Found 8 outliers among 100 measurements (8.00%)
3 (3.00%) low mild
2 (2.00%) high mild
3 (3.00%) high severe
aggregate_query_group_by_with_filter_u64 15 12 time: [777.83 us 782.75 us 788.15 us]
change: [-7.5157% -6.6393% -5.6558%] (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

FYI @jorgecarleitao

github-actions · 2020-12-07T19:02:27Z

https://issues.apache.org/jira/browse/ARROW-10837

Dandandan · 2020-12-07T21:13:35Z

As a next step after this, I think it would be interesting if we can have a look at calculating the hashes on the columns instead to benefit from the columnar data layout.

Some material I found on this:

https://www.cockroachlabs.com/blog/vectorized-hash-joiner/ (simple explanation)
https://pure.uva.nl/ws/files/4321270/68049_09.pdf

Please add if you know of more/newer material!

codecov-io · 2020-12-08T18:07:46Z

Codecov Report

Merging #8863 (008d3ea) into master (db94f24) will decrease coverage by 0.02%.
The diff coverage is n/a.

@@ Coverage Diff @@## master #8863 +/- ##
==========================================
- Coverage 77.03% 77.01% -0.03% 
==========================================
Files 173 173 Lines 40090 40101 +11 ==========================================
Hits 30885 30885 - Misses 9205 9216 +11

Impacted Files	Coverage Δ
...ust/datafusion/src/physical_plan/hash_aggregate.rs	`0.00% <ø> (ø)`
rust/datafusion/src/physical_plan/hash_join.rs	`0.00% <ø> (ø)`
rust/datafusion/tests/dataframe.rs	`0.00% <0.00%> (ø)`
rust/datafusion/src/datasource/csv.rs	`0.00% <0.00%> (ø)`
rust/datafusion/src/datasource/memory.rs	`0.00% <0.00%> (ø)`
rust/datafusion/src/datasource/parquet.rs	`0.00% <0.00%> (ø)`

Continue to review full report at Codecov.

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Dandandan · 2020-12-08T18:09:31Z

@jorgecarleitao

Just extended the change for hash aggregates as well.

Turns out, a good speedup as well for hash aggregate queries!

[This version]

Query 1 iteration 0 took 871 ms
Query 1 iteration 1 took 866 ms
Query 1 iteration 2 took 869 ms
Query 1 iteration 3 took 869 ms
Query 1 iteration 4 took 867 ms
Query 1 iteration 5 took 874 ms
Query 1 iteration 6 took 870 ms
Query 1 iteration 7 took 875 ms
Query 1 iteration 8 took 871 ms
Query 1 iteration 9 took 869 ms

[Master]

Query 1 iteration 0 took 1189 ms
Query 1 iteration 1 took 1192 ms
Query 1 iteration 2 took 1189 ms
Query 1 iteration 3 took 1185 ms
Query 1 iteration 4 took 1193 ms
Query 1 iteration 5 took 1202 ms
Query 1 iteration 6 took 1547 ms
Query 1 iteration 7 took 1242 ms
Query 1 iteration 8 took 1202 ms
Query 1 iteration 9 took 1197 ms

andygrove

Nice improvement!

jorgecarleitao

Good work and optimization!

codecov-commenter · 2026-04-05T17:53:18Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 77.01%. Comparing base (db94f24) to head (008d3ea).

Additional details and impacted files

@@ Coverage Diff @@## master #8863 +/- ##
==========================================
- Coverage 77.03% 77.01% -0.03% 
==========================================
Files 173 173 Lines 40090 40101 +11 ==========================================
Hits 30885 30885 - Misses 9205 9216 +11

☔ View full report in Codecov by Sentry.
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Dandandan added 11 commits November 24, 2020 22:17

Reduce size of key by boxing string
8bdefdf

Use Box<str>
8f1238d

Simplify using into
eb44aaa

Improve benchmarks
02d8da0

Format fixes
7d4ee70

Reduce to 16 bytes, use Box<[GroupByScalar]> for key
b28a6d4

Remove unnecessary Box around indices
9c8b8f0

Merge master
3a6127b

Use byte vec for hash key
feb13e4

Merge branch 'master' into key_byte_vec
26f479a

Fix imports
a2d441c

github-actionsBot added Component: Rust - DataFusion Component: Rust labels Dec 7, 2020

Dandandan changed the title ~~ARROW-10837: [Rust][DataFusion] Use Vec<u8> for hash join key values~~ARROW-10837: [Rust][DataFusion] Use Vec<u8> for hash join keysDec 7, 2020

github-actionsBot added the needs-rebase A PR that needs to be rebased by the author label Dec 7, 2020

Merge master
f1fc4dc

Dandandan marked this pull request as ready for review December 7, 2020 20:32

github-actionsBot removed the needs-rebase A PR that needs to be rebased by the author label Dec 7, 2020

Use for hash aggregate as well
3559d97

Dandandan changed the title ~~ARROW-10837: [Rust][DataFusion] Use Vec<u8> for hash join keys~~ARROW-10837: [Rust][DataFusion] Use Vec<u8> for hash keysDec 8, 2020

Dandandan added 2 commits December 8, 2020 19:21

Merge branch 'master' into key_byte_vec
379c3bd

Update comments
008d3ea

Dandandan mentioned this pull request Dec 10, 2020
ARROW-10812: [Rust] Make BooleanArray not a PrimitiveArray #8842
Closed

andygrove approved these changes Dec 10, 2020
View reviewed changes

jorgecarleitao approved these changes Dec 11, 2020
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jorgecarleitao closed this in 259fd71Dec 11, 2020

alamb mentioned this pull request Jul 28, 2021
Rework GroupByHash for faster performance and support grouping by nulls apache/datafusion#790
Closed

asfimport mentioned this pull request Dec 11, 2020
[Rust] Use Vec<u8> for hash key instead #26774
Closed

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