Pipeline aggregations are a new type of agg that can be used to perform processing on aggregation results. For example, you may use bucket/metric aggs to calculate the maximum price-per-day, and then a pipeline agg to find the average of those max prices.
This opens up a lot of possibilities for time-series analysis which were previously difficult or impossible, simply because bucket/metric aggregations cannot operate on sequentially ordered data (due to the distributed nature of that data).
There is a lot of work going into other areas which benefit metric data too: doc values are essentially a serialized column store, improvements in numeric compression and sparse bitsets in Lucene, etc
Purpose of this thread
I'd like to use this thread as the central location to discuss pipeline aggs, feature requests, questions, comments, or really anything related to metrics and time-series analysis in Elasticsearch.
In particular, if you have a time-series use case which cannot be built with pipeline aggs yet, let us know! It is early days for pipeline aggs, and we have a lot of ideas moving forward. User input is critical so we build functionality that is actually useful to you.
Resources and Links