I'm noticing some unexpected and undesirable behavior when using JSON Facet API
with Stats functions when using nested functions. Below is an example which
hopefully helps illustrate the behavior I'm seeing.
I have a JSON Facet string of the following:
json.facet={
"grp_0": {
"field": "ssnm",
"limit": -1,
"type": "terms",
"mincount": 1,
"refine": true,
"sort": {"index": "asc"},
"facet": {
"avg_TotalCpuUsec": "avg(TotalCpuUsec)",
"avg_sqrt_TotalCpuUsec": "avg(sqrt(TotalCpuUsec))",
"count_TotalCpuUsec": "countvals(TotalCpuUsec)",
"count_sqrt_TotalCpuUsec": "countvals(sqrt(TotalCpuUsec))",
"sum_TotalCpuUsec": "sum(TotalCpuUsec)",
"sum_sqrt_TotalCpuUsec": "sum(sqrt(TotalCpuUsec))"
}
}
}
And an example of one of the buckets returned is:
"facets":{
"count":32,
"grp_0":{
"buckets":[{
"val":"Activity",
"count":6,
"count_sqrt_TotalCpuUsec":6,
"sum_sqrt_TotalCpuUsec":495.29246931322893,
"count_TotalCpuUsec":4,
"sum_TotalCpuUsec":61464.399999999994,
"avg_TotalCpuUsec":15366.099999999999,
"avg_sqrt_TotalCpuUsec":82.54874488553816},
.
.
.
} ]}}}
Notice that there are 6 documents in the bucket, but only 4 of them have the
field "TotalCpuUsec", which is reflected in value for countvals(TotalCpuUsec).
My issue is with the calculation of avg(sqrt(TotalCpuUsec)). The calculation
of avg(TotalCpuUsec) is correct, equaling sum(TotalCpuUsec) / 4. However, the
value of avg(sqrt(TotalCpuUsec)) equals sum(sqrt(TotalCpuUsec)) / 6. I think
it should have been divided by 4, since only 4 documents have a value for this
field. It appears that sqrt(TotalCpuUsec) is returning 0.0 for documents that
don't have the field, so this 0.0 for the 2 documents is factoring into the avg
calculation, which seems to be reflected by the value of
countvals(sqrt(TotalCpuUsec)), which is 6.
This seems like a bug, but wanted to reach out to see if this is "working as
expected" and if there are some facet attributes that can be set to work around
this.
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