Percentiles aggregation #5323
Description
A percentiles aggregation would allow to compute (approximate) values of arbitrary percentiles based on the t-digest algorithm. Computing exact percentiles is not reasonably feasible as it would require shards to stream all values to the node that coordinates search execution, which could be gigabytes on a high-cardinality field. On the other hand, t-digest allows to trade accuracy for memory by trying to summarize the set of values that have been accumulated with interesting properties/features:
- compression is configurable, meaning that if you can configure it to have better accuracy at the cost of a higher memory usage,
- accuracy is excellent for extreme percentiles,
- percentiles are going to be accurate if few values were accumulated.
Example:
{
"aggs" : {
"load_time_outlier" : {
"percentiles" : {
"field" : "load_time",
"percents" : [95, 99, 99.9]
}
}
}
}