Thread-safe and persistent Golang implementations of probabilistic data structures: Bloom Filter, Cuckoo Filter, HyperLogLog, Count-Min Sketch and Top-K
This package provides two implementations of the data structures (a) In-memory (b) Redis backed. While keeping data in-memory has the advantages of being higly performant and yielding high throughput, it doesn't serve use cases of portability or communication of the underlying data so well. Take, for example, a setup where two applications are running to fulfill a goal. One of them writes the data and the other reads from it taking decisions based upon that. In this case, there should be a mechanism to share the underlying data structure for the two applications to do their tasks. With some trade-off to performance, this package solves that problem using Redis as the intermediate storage layer to achieve the same.
A Bloom filter is a space-efficient probabilistic data structure that is used to test whether an element is a member of a set. It provides a way to check for the presence of an element in a set without actually storing the entire set. Bloom filters are particularly useful in scenarios where memory is limited or when the exact membership information is not critical.
Refer: https://web.stanford.edu/~balaji/papers/bloom.pdf
package main
import (
"fmt"
"github.com/kwertop/gostatix"
)
func main() {
// create a new in-memory bloom filter with 1000000 items and a false positive rate of 0.0001
filter, _ := gostatix.NewMemBloomFilterWithParameters(1000000, 0.001)
e1 := []byte("cat")
e2 := []byte("dog")
// insert a few elements - "cat" and "dog"
filter.Insert(e1).Insert(e2)
// do a lookup for an element
ok := filter.Lookup(e1)
fmt.Printf("found cat, %v\n", ok) // found cat, true
ok = filter.Lookup([]byte("elephant"))
fmt.Printf("found elephant, %v\n", ok) // found elephant, false
}package main
import (
"fmt"
"github.com/kwertop/gostatix"
)
func main() {
// parse redis uri
redisConnOpt, _ := gostatix.ParseRedisURI("redis://127.0.0.1:6379")
// create redis connection
gostatix.MakeRedisClient(*redisConnOpt)
// create a new redis bloom filter with 1000000 items and a false positive rate of 0.0001
bloomRedis, _ := gostatix.NewRedisBloomFilterWithParameters(1000000, 0.001)
e1 := []byte("cat")
e2 := []byte("dog")
// insert a few elements - "cat" and "dog"
bloomRedis.Insert(e1).Insert(e2)
// do a lookup for an element
ok := bloomRedis.Lookup(e1)
fmt.Printf("found cat, %v\n", ok) // found cat, true
ok = filter.Lookup([]byte("elephant"))
fmt.Printf("found elephant, %v\n", ok) // found elephant, false
}A Cuckoo filter is a data structure used for approximate set membership queries, similar to a Bloom filter. It is designed to provide a compromise between memory efficiency, fast membership queries, and the ability to delete elements from the filter. Unlike a Bloom filter, a Cuckoo filter allows for efficient removal of elements while maintaining relatively low false positive rates. Refer: https://www.cs.cmu.edu/~dga/papers/cuckoo-conext2014.pdf
package main
import (
"fmt"
"github.com/kwertop/gostatix"
)
func main() {
// create a new in-memory cuckoo filter with 1000000 items and a false positive rate of 0.0001
// see doc for more details
filter := gostatix.NewCuckooFilterWithErrorRate(100000, 4, 100, 0.001)
e1 := []byte("cat")
e2 := []byte("dog")
// insert a few elements - "cat" and "dog"
filter.Insert(e1, false)
filter.Insert(e2, false)
// do a lookup for an element
ok := filter.Lookup(e1)
fmt.Printf("found cat, %v\n", ok) // found cat, true
ok = filter.Lookup([]byte("elephant"))
fmt.Printf("found elephant, %v\n", ok) // found elephant, false
ok = filter.Lookup(e2)
fmt.Printf("found dog, %v\n", ok) // found dog, true
//remove an element
_ = filter.Remove(e2)
ok = filter.Lookup(e2)
fmt.Printf("found dog, %v\n", ok) // found dog, false
}package main
import (
"fmt"
"github.com/kwertop/gostatix"
)
func main() {
// parse redis uri
redisConnOpt, _ := gostatix.ParseRedisURI("redis://127.0.0.1:6379")
// create redis connection
gostatix.MakeRedisClient(*redisConnOpt)
// create a new redis backed cuckoo filter with 1000000 items and a false positive rate of 0.0001
// see doc for more details
filter, _ := gostatix.NewCuckooFilterRedisWithErrorRate(1000000, 4, 100, 0.001)
// insert a few elements - "cat" and "dog"
filter.Insert(e1, false)
filter.Insert(e2, false)
// do a lookup for an element
ok, _ = filter.Lookup(e1)
fmt.Printf("found cat, %v\n", ok) // found cat, true
ok, _ = filter.Lookup([]byte("elephant"))
fmt.Printf("found elephant, %v\n", ok) // found elephant, false
ok, _ = filter.Lookup(e2)
fmt.Printf("found dog, %v\n", ok) // found dog, true
//remove an element
_, _ = filter.Remove(e2)
ok, _ = filter.Lookup(e2)
fmt.Printf("found dog, %v\n", ok) // found dog, false
}A probabilistic data structure used to estimate the frequency of items in a data stream. Refer: http://dimacs.rutgers.edu/~graham/pubs/papers/cm-full.pdf
package main
import (
"fmt"
"github.com/kwertop/gostatix"
)
func main() {
// create a new in-memory count-min sketch with error rate of 0.0001 and delta of 0.9999
sketch, _ := gostatix.NewCountMinSketchFromEstimates(0.0001, 0.9999)
e1 := []byte("cat")
e2 := []byte("dog")
// insert counts of few elements - "cat" and "dog"
sketch.Update(e1, 2)
sketch.Update(e2, 3)
sketch.Update(e1, 1)
// do a lookup for an count for any element
count := sketch.Count(e1)
fmt.Printf("found %v cats\n", count) // found 3 cats
}package main
import (
"fmt"
"github.com/kwertop/gostatix"
)
func main() {
// create redis connection
gostatix.MakeRedisClient(*redisConnOpt)
// create a new redis backed count-min sketch with error rate of 0.0001 and delta of 0.9999
sketch, _ := gostatix.NewCountMinSketchRedisFromEstimates(0.001, 0.999)
e1 := []byte("cat")
e2 := []byte("dog")
// insert counts of few elements - "cat" and "dog"
err := sketch.Update(e1, 2)
if err != nil {
fmt.Printf("error: %v\n", err)
}
sketch.Update(e2, 3)
sketch.Update(e1, 1)
// do a lookup for an count for any element
count, _ = sketch.Count(e1)
fmt.Printf("found %v cats\n", count) // found 3 cats
}A probabilistic data structure used for estimating the cardinality (number of unique elements) of in a very large dataset. Refer: https://static.googleusercontent.com/media/research.google.com/en//pubs/archive/40671.pdf
package main
import (
"fmt"
"github.com/kwertop/gostatix"
)
func main() {
// create a new in-memory hyperloglog with 4 registers
hll, _ := gostatix.NewHyperLogLog(4)
e1 := []byte("cat")
e2 := []byte("dog")
// insert counts of few elements
hll.Update(e1)
hll.Update(e2)
hll.Update(e1)
// do a lookup for count of distinct elements
distinct := hll.Count(true, true)
fmt.Printf("found %v distinct elements\n", distinct) // found 2 distinct elements
}package main
import (
"fmt"
"github.com/kwertop/gostatix"
)
func main() {
// parse redis uri
redisConnOpt, _ := gostatix.ParseRedisURI("redis://127.0.0.1:6379")
// create redis connection
gostatix.MakeRedisClient(*redisConnOpt)
// create a new redis backed hyperloglog with 4 registers
hll, _ := gostatix.NewHyperLogLogRedis(4)
e1 := []byte("cat")
e2 := []byte("dog")
// insert counts of few elements
hll.Update(e1)
hll.Update(e2)
hll.Update(e1)
// do a lookup for count of distinct elements
distinct, _ := hll.Count(true, true)
fmt.Printf("found %v distinct elements\n", distinct) // found 2 distinct elements
}It's a data structure designed to efficiently retrieve the "top-K" or "largest-K" elements from a dataset based on a certain criterion, such as frequency, value, or score.
package main
import (
"fmt"
"github.com/kwertop/gostatix"
)
func main() {
// create a new in-memory top-k with k=2, error rate of 0.001 and delta of 0.999
t := gostatix.NewTopK(2, 0.001, 0.999)
e1 := []byte("cat")
e2 := []byte("dog")
e3 := []byte("lion")
e4 := []byte("tiger")
// insert counts of few elements
t.Insert(e1, 3)
t.Insert(e2, 2)
t.Insert(e1, 1)
t.Insert(e3, 3)
t.Insert(e4, 1)
// do a lookup for top-k (2) elements
values := t.Values()
fmt.Printf("%v\n", values) // [{cat 4} {lion 3}]
}package main
import (
"fmt"
"github.com/kwertop/gostatix"
)
func main() {
// parse redis uri
redisConnOpt, _ := gostatix.ParseRedisURI("redis://127.0.0.1:6379")
// create redis connection
gostatix.MakeRedisClient(*redisConnOpt)
// create a new redis backed top-k with k=2, error rate of 0.001 and delta of 0.999
t1 := gostatix.NewTopKRedis(2, 0.001, 0.999)
e1 := []byte("cat")
e2 := []byte("dog")
e3 := []byte("lion")
e4 := []byte("tiger")
// insert counts of few elements
t1.Insert(e1, 3)
t1.Insert(e2, 2)
t1.Insert(e1, 1)
t1.Insert(e3, 3)
t1.Insert(e4, 1)
// do a lookup for top-k (2) elements
values1, _ := t1.Values()
fmt.Printf("%v\n", values1) // [{cat 4} {lion 3}]
}
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