hyperloglog-foxx adds HyperLogLog algorithm implementation as arangodb foxx app.
hyperloglog algorithm - by optimizely/hyperloglog
murmurhash3 hash algorithm by karanlyons/murmurHash.js
the state of each instance is stored as serialized JSON (string) under _hll key.
each instance weight is ~8kb at 12 registers with a mathematical error of ~1.6%.
The actual errors you might experience are 0.5-3%.
Lists of all HyperLogLog instances.
echo instance have a _card key that denotes the count of unique
values that were added to the instance. e.g cardinality.
Request:
curl -X GET -H "Accept: application/json" "http://localhost:8529/_db/_system/hll/hll"
Response:
[
{
"_key": "abcd",
"_card": 176
}
]
add value/s to a HyperLogLog instance.
to add multiple values use values key in body and add multiple values in an array of strings
Request:
curl -X POST -d @- http://localhost:8529/_db/_system/hll/hll/add <<EOF
{
"_key_" : "abcd",
"value": "my unique value"
}
EOF
Response:
[
{
"_key": "abcd",
"_card": 176
}
]
Return Codes:
200: added value/s and cardinality was changed.208: added value/s but cardinality wasn't changed.
Removes an HyperLogLog instance. Request:
curl -X DELETE -H "Accept: application/json" "http://localhost:8529/_db/_system/hll/hll/abcd"
Response:
{
"success": true
}
get specific instance by id. Request:
curl -X GET -H "Accept: application/json" "http://localhost:8529/_db/_system/hll/hll/abcd"
Response:
{
"_key": "abcd",
"_card": 176
}