The `exists` and `missing` filters need to merge postings lists of all existing
terms, which can be very costly, especially on high-cardinality fields. This
commit indexes the field names of a document under `_field_names` and reuses it
to speed up the `exists` and `missing` filters.
This is only enabled for indices that are created on or after Elasticsearch
1.3.0.
Close#5659
The `field_value_factor` function uses the value of a field in the
document to influence the score.
A query that looks like:
{
"query": {
"function_score": {
"query": {"match": { "body": "foo" }},
"functions": [
{
"field_value_factor": {
"field": "popularity",
"factor": 1.1,
"modifier": "square"
}
}
],
"score_mode": "max",
"boost_mode": "sum"
}
}
}
Would have the score modified by:
square(1.1 * doc['popularity'].value)
Closes#5519
hanneskaeufler
Adrien Grand
Lee Hinman
David Pilato
Konrad Feldmeier
Clinton Gormley