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add date field to decay function doc

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Britta Weber 2013-09-17 19:54:31 +02:00
parent bf41f56f24
commit b7c3b50909
1 changed files with 27 additions and 19 deletions
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44
docs/reference/query-dsl/queries/function-score-query.asciidoc
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@ -172,13 +172,30 @@ decay function is specified as
"FIELD_NAME": { "FIELD_NAME": {
"origin": "11, 12", "origin": "11, 12",
"scale": "2km", "scale": "2km",
"offset": "1km", "offset": "0km",
"decay": 0.33
}
}
--------------------------------------------------
where `DECAY_FUNCTION` can be "linear", "exp" and "gauss" (see below). The specified field must be a numeric field. In the above example, the field is a <<mapping-geo-point-type>> and origin can be provided in geo format. `scale` and `offset` must be given with a unit in this case. If your field is a date field, you can set `scale` and `offset` as days, weeks, and so on. Example:
[source,js]
--------------------------------------------------
"DECAY_FUNCTION": {
"FIELD_NAME": {
"origin": "2013-09-17",
"scale": "10d",
"offset": "5d",
"decay" : 0.5 "decay" : 0.5
} }
} }
-------------------------------------------------- --------------------------------------------------
where `DECAY_FUNCTION` can be "linear", "exp" and "gauss" (see below).
The format of the origin depends on the <<mapping-date-format>> defined in your mapping. If you do not define the origin, the current time is used.
The `offset` and `decay` parameters are optional. The `offset` and `decay` parameters are optional.
[horizontal] [horizontal]
@ -192,30 +209,21 @@ The `offset` and `decay` parameters are optional.
given at `scale`. If no `decay` is defined, documents at the distance given at `scale`. If no `decay` is defined, documents at the distance
`scale` will be scored 0.5. `scale` will be scored 0.5.
For example, your documents might represents hotels and contain a geo In the first example, your documents might represents hotels and contain a geo
location field. You want to compute a decay function depending on how location field. You want to compute a decay function depending on how
far the hotel is from a given location. You might not immediately see far the hotel is from a given location. You might not immediately see
what scale to choose for the gauss function, but you can say something what scale to choose for the gauss function, but you can say something
like: "At a distance of 2km from the desired location, the score should like: "At a distance of 2km from the desired location, the score should
be reduced by one third." be reduced by one third."
You can provide this parameter like this:
[source,js]
--------------------------------------------------
"DECAY_FUNCTION": {
"location": {
"origin": "11, 12",
"scale": "2km",
"decay" : 0.33
}
}
--------------------------------------------------
The parameter "scale" will then be adjusted automatically to assure that The parameter "scale" will then be adjusted automatically to assure that
the score function computes a score of 0.33 for hotels that are 2km away the score function computes a score of 0.5 for hotels that are 2km away
from the desired location. from the desired location.
In the second example, documents with a field value between 2013-09-12 and 2013-09-22 would get a weight of 1.0 and documents which are 15 days from that date a weight of 0.5.
The `DECAY_FUNCTION` determines the shape of the decay: The `DECAY_FUNCTION` determines the shape of the decay:
[horizontal] [horizontal]