Sampler aggregation
/ Sampler, / AggregationSampler aggregation #
A single-bucket aggregation that keeps only a sample of the matching
documents before running its sub-aggregations — used to cut aggregation
cost on very large result sets. If a terms aggregation over millions
of documents is too slow or too memory-hungry, sampling trades exact
counts for an order-of-magnitude answer at a fraction of the cost.
How it works #
The sampler keeps the first shard_size matching documents (default
100) and discards the rest; its sub-aggregations then run over that
sample only. The result is a single bucket keyed sample, carrying the
sample’s doc_count and the sub-aggregation results: