Genericize RoaringBitmap and implements Roaring32 and Roaring64 #260
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grim7reaper
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| /// A generic compressed bitmap using the [Roaring bitmap compression scheme](https://roaringbitmap.org/). | ||
| #[derive(PartialEq)] | ||
| pub struct RoaringBitmap<V: Value> { | ||
| containers: Vec<container::Container<V>>, |
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I worry that using a Vec for RoaringBitmap64 might not be the best idea. For RoaringBitmap32, in the worst case, we're moving around 64k containers, but for RoaringBitmap64, inserting a new container may involve quite a lot of copying, which is why the original used a BTreeMap instead.
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I guess that's depends on the distribution of your dataset/workload, using a BTreeMap isn't great either in term locality/pointer chasing.
I would say that for most of the case it should be fine, at least the paper didn't notice large difference in memory usage.
But maybe both approach should be offered?
This will allows to easily implement Roaring64, a 64-bit RoaringBitmap using the TwoLevelRoaringBitmap approach, which is up to 11x faster than the RoaringTreemap approach and reuse most of Roaring32 code. Note that RoaringBitmap::full have been removed because it won't scale for Roaring64. Comment out RoaringTreemap for now, will be replaced in the next commit.
Benchmark results on insert_range (only bench available for 64-bit):
group roaring64 treemap
----- --------- -------
from_empty_1000 1.00 87.6±4.76ns 10.6 GElem/sec 1.65 144.2±1.28ns 6.5 GElem/sec
from_empty_10000 1.00 166.8±9.32ns 55.8 GElem/sec 1.28 213.6±7.26ns 43.6 GElem/sec
from_empty_8589934590 1.01 151.5±0.99ms 52.8 GElem/sec 1.00 149.7±1.00ms 53.5 GElem/sec
pre_populated_1000 1.00 139.3±19.83ns 6.7 GElem/sec 1.30 180.8±20.70ns 5.2 GElem/sec
pre_populated_10000 1.00 235.4±83.29ns 39.6 GElem/sec 1.26 295.9±106.25ns 31.5 GElem/sec
pre_populated_8589934590 1.00 74.8±2.56ms 107.0 GElem/sec 1.01 75.3±1.82ms 106.3 GElem/sec
Done in the last commit |
Roaring32is the new name ofRoaringBitmap(which is now the core generic implementation,RoaringBitmap<V>).Roaring64is the 64-bit version and replacesRoaringTreemap.