[Downsampling++] Aggregate metric double should support all functions that gauge supported. #134294
Description
Description
When we downsample an index, gauge fields are converted to aggregate_metric_double which stores an pre-aggregated representation of the gauge values that belonged to the same interval.
Currently, the aggregate_metric_double can support accurately the following ES|QL functions:
- AVG ([ES|QL] Support avg on aggregate metric double #130421)
- MAX,
- MIN,
- SUM,
- COUNT
Other functions are not supported yet. We would like to use the default value (usually max) of aggregate_metric_double to approximate result of the ES|QL functions as they would be applied on the original data. Considering that downsampled data only have min, max, sum and count the result will not have the same accuracy as the original data.