Discrepancy between doc_count agg and histogram agg on histogram fields #74617
Description
It looks like there is a bug when performing a histogram aggregation on a histogram field, if the document contains _doc_count field.
Expected
doc_count agg and histogram agg should return identical doc counts.
Actual:
The doc count is (almost) doubled for histogram agg compared to the doc_count agg
Affected version
{
"number" : "8.0.0-SNAPSHOT",
"build_flavor" : "default",
"build_type" : "docker",
"build_hash" : "307b82c474fe27722863fa2dc6b05def2f608ad9",
"build_date" : "2021-06-27T01:39:13.126072914Z",
"build_snapshot" : true,
"lucene_version" : "8.9.0",
"minimum_wire_compatibility_version" : "7.14.0",
"minimum_index_compatibility_version" : "7.0.0"
}Reproduce problem
PUT histogram-double-bug
{
"mappings" : {
"properties" : {
"my_histogram" : {
"type" : "histogram"
}
}
}
}
POST histogram-double-bug/_doc
{
"_doc_count": 10,
"my_histogram": {
"counts": [
10
],
"values": [
20
]
}
}
GET histogram-double-bug/_search?track_total_hits=true
{
"size": 0,
"aggs": {
"doc_count": {
"value_count": {
"field": "my_histogram"
}
},
"distribution": {
"histogram": {
"field": "my_histogram",
"interval": 1000
}
}
}
}
Response
{
"took" : 0,
"timed_out" : false,
"_shards" : {
"total" : 1,
"successful" : 1,
"skipped" : 0,
"failed" : 0
},
"hits" : {
"total" : {
"value" : 1,
"relation" : "eq"
},
"max_score" : null,
"hits" : [ ]
},
"aggregations" : {
"doc_count" : {
"value" : 10
},
"distribution" : {
"buckets" : [
{
"key" : 0.0,
"doc_count" : 19
}
]
}
}
}In the above, the correct doc count is 10 but the histogram doc count is 19.