Improved hybrid rle decoding performance ~-40% #203
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ritchie46
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Nov 26, 2022
| @@ -25,6 +25,9 @@ enum State<'a> { | |||
| None, | |||
| Bitpacked(bitpacked::Decoder<'a, u32>), | |||
| Rle(std::iter::Take<std::iter::Repeat<u32>>), | |||
| // Add a special branch for a single value to | |||
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The new Single state that represent a single value. This branch is hot, hot, hot!
Codecov ReportBase: 85.75% // Head: 85.68% // Decreases project coverage by
Additional details and impacted files@@ Coverage Diff @@
## main #203 +/- ##
==========================================
- Coverage 85.75% 85.68% -0.07%
==========================================
Files 84 84
Lines 8233 8256 +23
==========================================
+ Hits 7060 7074 +14
- Misses 1173 1182 +9
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This is an amazing idea! |
ritchie46
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jorgecarleitao
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Due to the law of small numbers most values are 1 and therefore extending with a
std::iter::repeat(value).take(1)is a large overhead. This adds an extraStatebranch for the single value case.This reduces reading a single column with uuid strings by ca 40% on my real world dataset.
I also have removed a redundant
Errorfrom the types. There are more of those redundant errors that I want to follow up in a later PR.