roaring [](https://travis-ci.org/RoaringBitmap/roaring) [](https://coveralls.io/github/RoaringBitmap/roaring?branch=master) [](https://godoc.org/github.com/RoaringBitmap/roaring) [](https://goreportcard.com/report/github.com/RoaringBitmap/roaring)
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=============
This is a go version of the Roaring bitmap data structure.
Roaring bitmaps are used by several major systems such as [Apache Lucene][lucene] and derivative systems such as [Solr][solr] and
[Elasticsearch][elasticsearch], [Apache Druid (Incubating)][druid], [LinkedIn Pinot][pinot], [Netflix Atlas][atlas], [Apache Spark][spark], [OpenSearchServer][opensearchserver], [Cloud Torrent][cloudtorrent], [Whoosh][whoosh], [Pilosa][pilosa], [Microsoft Visual Studio Team Services (VSTS)][vsts], and eBay's [Apache Kylin][kylin].
[lucene]: https://lucene.apache.org/
[solr]: https://lucene.apache.org/solr/
[elasticsearch]: https://www.elastic.co/products/elasticsearch
[druid]: https://druid.apache.org/
[spark]: https://spark.apache.org/
[opensearchserver]: http://www.opensearchserver.com
[cloudtorrent]: https://github.com/jpillora/cloud-torrent
[whoosh]: https://bitbucket.org/mchaput/whoosh/wiki/Home
[pilosa]: https://www.pilosa.com/
[kylin]: http://kylin.apache.org/
[pinot]: http://github.com/linkedin/pinot/wiki
[vsts]: https://www.visualstudio.com/team-services/
[atlas]: https://github.com/Netflix/atlas
Roaring bitmaps are found to work well in many important applications:
> Use Roaring for bitmap compression whenever possible. Do not use other bitmap compression methods ([Wang et al., SIGMOD 2017](http://db.ucsd.edu/wp-content/uploads/2017/03/sidm338-wangA.pdf))
The ``roaring`` Go library is used by
* [Cloud Torrent](https://github.com/jpillora/cloud-torrent): a self-hosted remote torrent client
* [runv](https://github.com/hyperhq/runv): an Hypervisor-based runtime for the Open Containers Initiative
* [InfluxDB](https://www.influxdata.com)
* [Pilosa](https://www.pilosa.com/)
* [Bleve](http://www.blevesearch.com)
This library is used in production in several systems, it is part of the [Awesome Go collection](https://awesome-go.com).
There are also [Java](https://github.com/RoaringBitmap/RoaringBitmap) and [C/C++](https://github.com/RoaringBitmap/CRoaring) versions. The Java, C, C++ and Go version are binary compatible: e.g, you can save bitmaps
from a Java program and load them back in Go, and vice versa. We have a [format specification](https://github.com/RoaringBitmap/RoaringFormatSpec).
This code is licensed under Apache License, Version 2.0 (ASL2.0).
Copyright 2016-... by the authors.
### References
- Daniel Lemire, Owen Kaser, Nathan Kurz, Luca Deri, Chris O'Hara, François Saint-Jacques, Gregory Ssi-Yan-Kai, Roaring Bitmaps: Implementation of an Optimized Software Library, Software: Practice and Experience 48 (4), 2018 [arXiv:1709.07821](https://arxiv.org/abs/1709.07821)
- Samy Chambi, Daniel Lemire, Owen Kaser, Robert Godin,
Better bitmap performance with Roaring bitmaps,
Software: Practice and Experience 46 (5), 2016.
http://arxiv.org/abs/1402.6407 This paper used data from http://lemire.me/data/realroaring2014.html
- Daniel Lemire, Gregory Ssi-Yan-Kai, Owen Kaser, Consistently faster and smaller compressed bitmaps with Roaring, Software: Practice and Experience 46 (11), 2016. http://arxiv.org/abs/1603.06549
### Dependencies
Dependencies are fetched automatically by giving the `-t` flag to `go get`.
they include
- github.com/willf/bitset
- github.com/mschoch/smat
- github.com/glycerine/go-unsnap-stream
- github.com/philhofer/fwd
- github.com/jtolds/gls
Note that the smat library requires Go 1.6 or better.
#### Installation
- go get -t github.com/RoaringBitmap/roaring
### Example
Here is a simplified but complete example:
```go
package main
import (
"fmt"
"github.com/RoaringBitmap/roaring"
"bytes"
)
func main() {
// example inspired by https://github.com/fzandona/goroar
fmt.Println("==roaring==")
rb1 := roaring.BitmapOf(1, 2, 3, 4, 5, 100, 1000)
fmt.Println(rb1.String())
rb2 := roaring.BitmapOf(3, 4, 1000)
fmt.Println(rb2.String())
rb3 := roaring.New()
fmt.Println(rb3.String())
fmt.Println("Cardinality: ", rb1.GetCardinality())
fmt.Println("Contains 3? ", rb1.Contains(3))
rb1.And(rb2)
rb3.Add(1)
rb3.Add(5)
rb3.Or(rb1)
// computes union of the three bitmaps in parallel using 4 workers
roaring.ParOr(4, rb1, rb2, rb3)
// computes intersection of the three bitmaps in parallel using 4 workers
roaring.ParAnd(4, rb1, rb2, rb3)
// prints 1, 3, 4, 5, 1000
i := rb3.Iterator()
for i.HasNext() {
fmt.Println(i.Next())
}
fmt.Println()
// next we include an example of serialization
buf := new(bytes.Buffer)
rb1.WriteTo(buf) // we omit error handling
newrb:= roaring.New()
newrb.ReadFrom(buf)
if rb1.Equals(newrb) {
fmt.Println("I wrote the content to a byte stream and read it back.")
}
// you can iterate over bitmaps using ReverseIterator(), Iterator, ManyIterator()
}
```
If you wish to use serialization and handle errors, you might want to
consider the following sample of code:
```go
rb := BitmapOf(1, 2, 3, 4, 5, 100, 1000)
buf := new(bytes.Buffer)
size,err:=rb.WriteTo(buf)
if err != nil {
t.Errorf("Failed writing")
}
newrb:= New()
size,err=newrb.ReadFrom(buf)
if err != nil {
t.Errorf("Failed reading")
}
if ! rb.Equals(newrb) {
t.Errorf("Cannot retrieve serialized version")
}
```
Given N integers in [0,x), then the serialized size in bytes of
a Roaring bitmap should never exceed this bound:
`` 8 + 9 * ((long)x+65535)/65536 + 2 * N ``
That is, given a fixed overhead for the universe size (x), Roaring
bitmaps never use more than 2 bytes per integer. You can call
``BoundSerializedSizeInBytes`` for a more precise estimate.
### Documentation
Current documentation is available at http://godoc.org/github.com/RoaringBitmap/roaring
### Goroutine safety
In general, it should not generally be considered safe to access
the same bitmaps using different goroutines--they are left
unsynchronized for performance. Should you want to access
a Bitmap from more than one goroutine, you should
provide synchronization. Typically this is done by using channels to pass
the *Bitmap around (in Go style; so there is only ever one owner),
or by using `sync.Mutex` to serialize operations on Bitmaps.
### Coverage
We test our software. For a report on our test coverage, see
https://coveralls.io/github/RoaringBitmap/roaring?branch=master
### Benchmark
Type
go test -bench Benchmark -run -
To run benchmarks on [Real Roaring Datasets](https://github.com/RoaringBitmap/real-roaring-datasets)
run the following:
```sh
go get github.com/RoaringBitmap/real-roaring-datasets
BENCH_REAL_DATA=1 go test -bench BenchmarkRealData -run -
```
### Iterative use
You can use roaring with gore:
- go get -u github.com/motemen/gore
- Make sure that ``$GOPATH/bin`` is in your ``$PATH``.
- go get github.com/RoaringBitmap/roaring
```go
$ gore
gore version 0.2.6 :help for help
gore> :import github.com/RoaringBitmap/roaring
gore> x:=roaring.New()
gore> x.Add(1)
gore> x.String()
"{1}"
```
### Fuzzy testing
You can help us test further the library with fuzzy testing:
go get github.com/dvyukov/go-fuzz/go-fuzz
go get github.com/dvyukov/go-fuzz/go-fuzz-build
go test -tags=gofuzz -run=TestGenerateSmatCorpus
go-fuzz-build github.com/RoaringBitmap/roaring
go-fuzz -bin=./roaring-fuzz.zip -workdir=workdir/ -timeout=200
Let it run, and if the # of crashers is > 0, check out the reports in
the workdir where you should be able to find the panic goroutine stack
traces.
### Alternative in Go
There is a Go version wrapping the C/C++ implementation https://github.com/RoaringBitmap/gocroaring
For an alternative implementation in Go, see https://github.com/fzandona/goroar
The two versions were written independently.
### Mailing list/discussion group
https://groups.google.com/forum/#!forum/roaring-bitmaps