fix: column aware row encoding: improve the implementation and add bench #17818
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BugenZhao
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Jul 26, 2024
src/common/src/util/value_encoding/column_aware_row_encoding.rs
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The sorted implementation is still 10% faster than this hash-table implementation.
Considering the effort of refactoring the code and additional logic for compatibility, perhaps we can postpone it until necessary. |
fuyufjh
commented
Jul 26, 2024
src/common/src/util/value_encoding/column_aware_row_encoding.rs
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BugenZhao
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Jul 26, 2024
| @@ -176,7 +168,7 @@ impl ValueRowSerializer for Serializer { | |||
| /// Should non-null default values be specified, a new field could be added to Deserializer | |||
| #[derive(Clone)] | |||
| pub struct Deserializer { | |||
| needed_column_ids: BTreeMap<i32, usize>, | |||
| required_column_ids: HashMap<i32, usize>, | |||
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Interesting. I thought BTreeMap is faster when there are only a few entries: https://arc.net/l/quote/okdycbqi
The current value of B is 6. According to this, can we also benchmark the case for a table containing less than 6 columns?
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Added bench column_aware_row_encoding_4_columns. Observed a similar performance improvement.
Benchmarking column_aware_row_encoding_16_columns_encode: Collecting 100 samples in estimated 5.0015
column_aware_row_encoding_16_columns_encode
time: [491.00 ns 492.30 ns 493.95 ns]
change: [-3.6361% -2.8341% -2.0340%] (p = 0.00 < 0.05)
Performance has improved.
Found 10 outliers among 100 measurements (10.00%)
6 (6.00%) high mild
4 (4.00%) high severe
Benchmarking column_aware_row_encoding_16_columns_decode: Collecting 100 samples in estimated 5.0011
column_aware_row_encoding_16_columns_decode
time: [445.62 ns 448.76 ns 451.61 ns]
change: [-51.073% -50.248% -49.515%] (p = 0.00 < 0.05)
Performance has improved.
Found 7 outliers among 100 measurements (7.00%)
3 (3.00%) low mild
2 (2.00%) high mild
2 (2.00%) high severe
Benchmarking column_aware_row_encoding_4_columns_encode: Collecting 100 samples in estimated 5.0009 s (23M iter
column_aware_row_encoding_4_columns_encode
time: [221.45 ns 224.51 ns 228.98 ns]
change: [+0.1302% +0.7332% +1.4856%] (p = 0.03 < 0.05)
Change within noise threshold.
Found 7 outliers among 100 measurements (7.00%)
2 (2.00%) high mild
5 (5.00%) high severe
Benchmarking column_aware_row_encoding_4_columns_decode: Collecting 100 samples in estimated 5.0004 s (38M iter
column_aware_row_encoding_4_columns_decode
time: [131.47 ns 131.82 ns 132.26 ns]
change: [-46.562% -46.074% -45.656%] (p = 0.00 < 0.05)
Performance has improved.
Found 11 outliers among 100 measurements (11.00%)
1 (1.00%) low mild
5 (5.00%) high mild
5 (5.00%) high severe
src/common/src/util/value_encoding/column_aware_row_encoding.rs
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stdrc
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Jul 30, 2024
fuyufjh
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What's changed and what's your intention?
Resolves #16763
Unfortunately, currently we don't ensure the persisted column IDs to be sorted. For example,
create table t (a varchar, b int, c int)will create a state table that has column ids1,2,3,0, where0always refers to_row_id.As a result, I reverted the order-based implementation and use a hash-table now.
Benchmark result (on my MacBook)
Why
ahash::HashMap?According to my benchmark,
ahash::HashMapis the fastest implementation.Checklist
./risedev check(or alias,./risedev c)Documentation
Release note
If this PR includes changes that directly affect users or other significant modifications relevant to the community, kindly draft a release note to provide a concise summary of these changes. Please prioritize highlighting the impact these changes will have on users.