Elasticsearch: aggregation min_doc_count for weeks doesn't work - hadoop

Question

I've the following aggregation with interval=week and min_doc_count=0
{
"aggs": {
"scores_by_date": {
"date_histogram": {
"field": "date",
"format": "yyyy-MM-dd",
"interval": "week",
"min_doc_count": 0
}
}
}
and date filter from Jan-01-2015 to Feb-23-2015
{
"range": {
"document.date": {
"from": "2015-01-01",
"to": "2015-02-23"
}
}
}
I expected Elasticsearch to fill seven weeks even if empty and return buckets but end up only with one item in it
{
"aggregations": {
"scores_by_date": {
"buckets": [
{
"key_as_string": "2015-01-05",
"key": 1420416000000,
"doc_count": 5
}
]
}
}
}
Elasticsearch version: 1.4.0
What is wrong with my aggregation or how can I say Elasticsearch to fill missing weeks?

Answer 1

You can try specifying extended bounds (there's documentation discussing this feature on the official doc page for histogram aggregations). The most relevant nugget from those docs is this:
With extended_bounds setting, you now can "force" the histogram aggregation to start building buckets on a specific min values and also keep on building buckets up to a max value (even if there are no documents anymore). Using extended_bounds only makes sense when min_doc_count is 0 (the empty buckets will never be returned if min_doc_count is greater than 0).
So your aggregation may have to look something like this to force ES to return empty buckets in that range:
{
"aggs": {
"scores_by_date": {
"date_histogram": {
"field": "date",
"format": "yyyy-MM-dd",
"interval": "week",
"min_doc_count": 0,
"extended_bounds" : {
"min" : "2015-01-01",
"max" : "2015-02-23"
}
}
}
}