README
¶
sroar: Serialized Roaring Bitmaps
sroar is a re-written version of Roaring Bitmaps in Go, with the aim to have equality between in-memory representation and on-disk representation. An sroar.Bitmap does not need to be marshalled or unmarshalled, as the underlying represetation is a byte slice. Therefore, it can be written to disk, brought to memory, or shipped over the network immediately. This is needed in Dgraph, where we need to deal with lots of bitmaps.
sroar only implements array and bitmap containers. It does NOT implement run containers, which is an optimization that RoaringBitmaps has. Despite that, it outperforms RoaringBitmaps as shown in the Benchmarks section.
The code borrows concepts and code from RoaringBitmaps.
Benchmarks
The benchmarks were run:
- Using real data set as described in RoaringBitmaps.
- Only on the 64-bit version of roaring bitmaps (roaring64).
- Only on
FastOr, which is the more expensive operation thanAndor equivalent. - On AMD Ryzen Threadripper 2950X 16-Core Processor.
- Using Go benchmarks serially.
Based on the benchmarks, sroar is:
- 6.5x faster (-85% p50) for benchmarks >1ms, uses
- 15x (-93.5% p50) less memory for allocations >1MB.
- 25x fewer allocations.
The benchmark command and the results are:
$ go test -bench BenchmarkRealDataFastOr --run=XXX --count=5 --benchmem
name CPU old time/op new time/op delta
RealDataFastOr/census1881-32 302ms ± 2% 2ms ± 3% -99.29% (p=0.008 n=5+5)
RealDataFastOr/wikileaks-noquotes-32 76.5ms ± 1% 0.9ms ± 1% -98.83% (p=0.008 n=5+5)
RealDataFastOr/wikileaks-noquotes_srt-32 34.8ms ± 5% 1.0ms ± 2% -97.07% (p=0.008 n=5+5)
RealDataFastOr/dimension_033-32 55.0ms ± 3% 2.7ms ± 0% -95.16% (p=0.016 n=5+4)
RealDataFastOr/census1881_srt-32 36.8ms ± 3% 2.9ms ± 1% -92.13% (p=0.008 n=5+5)
RealDataFastOr/dimension_003-32 50.4ms ± 1% 11.6ms ± 4% -77.06% (p=0.008 n=5+5)
RealDataFastOr/dimension_008-32 10.0ms ± 2% 3.7ms ± 2% -62.69% (p=0.008 n=5+5)
RealDataFastOr/weather_sept_85_srt-32 6.13ms ± 3% 2.72ms ± 2% -55.66% (p=0.008 n=5+5)
RealDataFastOr/census-income-32 1.70ms ± 3% 1.05ms ± 1% -38.53% (p=0.008 n=5+5)
RealDataFastOr/weather_sept_85-32 2.28ms ± 2% 4.07ms ± 2% +78.52% (p=0.008 n=5+5)
RealDataFastOr/uscensus2000-32 556µs ± 2% 791µs ± 1% +42.17% (p=0.008 n=5+5)
RealDataFastOr/census-income_srt-32 260µs ± 4% 986µs ± 2% +279.09% (p=0.008 n=5+5)
name MEM_BYTES old alloc/op new alloc/op delta
RealDataFastOr/census1881-32 585MB ± 0% 1MB ± 0% -99.75% (p=0.008 n=5+5)
RealDataFastOr/wikileaks-noquotes-32 76.3MB ± 0% 0.6MB ± 0% -99.24% (p=0.008 n=5+5)
RealDataFastOr/wikileaks-noquotes_srt-32 22.8MB ± 0% 0.6MB ± 0% -97.46% (p=0.008 n=5+5)
RealDataFastOr/census1881_srt-32 15.3MB ± 0% 1.4MB ± 0% -90.58% (p=0.008 n=5+5)
RealDataFastOr/dimension_003-32 7.78MB ± 0% 1.44MB ± 0% -81.49% (p=0.008 n=5+5)
RealDataFastOr/dimension_033-32 1.10MB ± 0% 1.44MB ± 0% +30.92% (p=0.008 n=5+5)
RealDataFastOr/dimension_008-32 537kB ± 0% 97kB ± 0% -81.94% (p=0.008 n=5+5)
RealDataFastOr/census-income-32 187kB ± 0% 70kB ± 0% -62.86% (p=0.008 n=5+5)
RealDataFastOr/census-income_srt-32 99.1kB ± 0% 69.6kB ± 0% -29.81% (p=0.008 n=5+5)
RealDataFastOr/weather_sept_85_srt-32 375kB ± 0% 292kB ± 0% -21.95% (p=0.008 n=5+5)
RealDataFastOr/uscensus2000-32 169kB ± 0% 231kB ± 0% +36.97% (p=0.008 n=5+5)
RealDataFastOr/weather_sept_85-32 169kB ± 0% 292kB ± 0% +72.93% (p=0.008 n=5+5)
name MEM_ALLOCS old allocs/op new allocs/op delta
RealDataFastOr/census1881_srt-32 29.7k ± 0% 0.0k ± 0% -99.91% (p=0.008 n=5+5)
RealDataFastOr/wikileaks-noquotes_srt-32 6.06k ± 0% 0.02k ± 0% -99.74% (p=0.008 n=5+5)
RealDataFastOr/dimension_003-32 4.57k ± 0% 0.03k ± 2% -99.42% (p=0.008 n=5+5)
RealDataFastOr/dimension_033-32 4.33k ± 0% 0.03k ± 0% -99.38% (p=0.000 n=5+4)
RealDataFastOr/uscensus2000-32 1.75k ± 0% 0.06k ± 0% -96.85% (p=0.008 n=5+5)
RealDataFastOr/dimension_008-32 704 ± 0% 23 ± 3% -96.79% (p=0.008 n=5+5)
RealDataFastOr/census-income-32 271 ± 0% 9 ± 0% -96.68% (p=0.008 n=5+5)
RealDataFastOr/weather_sept_85_srt-32 248 ± 0% 14 ± 0% -94.35% (p=0.008 n=5+5)
RealDataFastOr/weather_sept_85-32 81.0 ± 0% 14.0 ± 0% -82.72% (p=0.008 n=5+5)
RealDataFastOr/census-income_srt-32 40.0 ± 0% 9.0 ± 0% -77.50% (p=0.008 n=5+5)
RealDataFastOr/census1881-32 54.5k ± 0% 0.0k ± 0% ~ (p=0.079 n=4+5)
RealDataFastOr/wikileaks-noquotes-32 39.2k ± 0% 0.0k ± 0% ~ (p=0.079 n=4+5)
Documentation
¶
Index ¶
- func Memclr(b []uint16)
- type Bitmap
- func And(a, b *Bitmap) *Bitmap
- func FastAnd(bitmaps ...*Bitmap) *Bitmap
- func FastOr(bitmaps ...*Bitmap) *Bitmap
- func FastParOr(numGo int, bitmaps ...*Bitmap) *Bitmap
- func FromBuffer(data []byte) *Bitmap
- func FromBufferWithCopy(src []byte) *Bitmap
- func FromSortedList(vals []uint64) *Bitmap
- func NewBitmap() *Bitmap
- func NewBitmapWith(numKeys int) *Bitmap
- func Or(a, b *Bitmap) *Bitmap
- func (ra *Bitmap) And(bm *Bitmap)
- func (ra *Bitmap) AndNot(bm *Bitmap)
- func (ra *Bitmap) Capacity() int
- func (ra *Bitmap) Cleanup()
- func (ra *Bitmap) Clone() *Bitmap
- func (ra *Bitmap) Contains(x uint64) bool
- func (ra *Bitmap) Debug(x uint64) string
- func (ra *Bitmap) GetCardinality() int
- func (ra *Bitmap) IsEmpty() bool
- func (r *Bitmap) ManyIterator() *ManyItr
- func (ra *Bitmap) Maximum() uint64
- func (ra *Bitmap) Minimum() uint64
- func (bm *Bitmap) NewIterator() *Iterator
- func (bm *Bitmap) NewRangeIterators(numRanges int) []*Iterator
- func (dst *Bitmap) Or(src *Bitmap)
- func (ra *Bitmap) Rank(x uint64) int
- func (ra *Bitmap) Remove(x uint64) bool
- func (ra *Bitmap) RemoveRange(lo, hi uint64)
- func (ra *Bitmap) Reset()
- func (ra *Bitmap) Select(x uint64) (uint64, error)
- func (ra *Bitmap) Set(x uint64) bool
- func (ra *Bitmap) SetMany(vals []uint64)
- func (ra *Bitmap) Size() int
- func (bm *Bitmap) Split(externalSize func(start, end uint64) uint64, maxSz uint64) []*Bitmap
- func (ra *Bitmap) String() string
- func (ra *Bitmap) ToArray() []uint64
- func (ra *Bitmap) ToBuffer() []byte
- func (ra *Bitmap) ToBufferWithCopy() []byte
- type Iterator
- type ManyItr
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
Types ¶
type Bitmap ¶
type Bitmap struct {
// contains filtered or unexported fields
}
func FastOr ¶
FastOr would merge given Bitmaps into one Bitmap. This is faster than doing an OR over the bitmaps iteratively.
func FastParOr ¶
FastParOr would group up bitmaps and call FastOr on them concurrently. It would then merge the groups into final Bitmap. This approach is simpler and faster than operating at a container level, because we can't operate on array containers belonging to the same Bitmap concurrently because array containers can expand, leaving no clear boundaries.
If FastParOr is called with numGo=1, it just calls FastOr.
Experiments with numGo=4 shows that FastParOr would be 2x the speed of FastOr, but 4x the memory usage, even under 50% CPU usage. So, use wisely.
func FromBuffer ¶
FromBuffer returns a pointer to bitmap corresponding to the given buffer. This bitmap shouldn't be modified because it might corrupt the given buffer.
func FromBufferWithCopy ¶
FromBufferWithCopy creates a copy of the given buffer and returns a bitmap based on the copied buffer. This bitmap is safe for both read and write operations.
func FromSortedList ¶
func NewBitmapWith ¶
func (*Bitmap) Capacity ¶
Capacity returns the underlying arrays uint16 capacity. used to reduce amount of reallocations.
func (*Bitmap) GetCardinality ¶
func (*Bitmap) ManyIterator ¶
TODO: See if this is needed, we should remove this
func (*Bitmap) NewIterator ¶
func (*Bitmap) NewRangeIterators ¶
func (*Bitmap) RemoveRange ¶
Remove range removes [lo, hi) from the bitmap.
func (*Bitmap) Split ¶
Split splits the bitmap based on maxSz and the externalSize function. It splits the bitmap such that size of each split bitmap + external size corresponding to its elements approximately equal to maxSz (it can be greater than maxSz sometimes). The splits are returned in sorted order. externalSize is a function that should return the external size corresponding to elements in range [start, end]. External size is used to calculate the split boundaries.
Source Files