DynaRank Plugin provides a feature for Dynamic Ranking at a search time. You can change top N documents in the search result with your re-ordering algorithm. Elasticsearch has rescoring, but DynaRank is different as below:
- DynaRank's reranking is executed on requested node only, not on each shard.
- DynaRank uses a script language for reranking.
| Version | Elasticsearch |
|---|---|
| master | 2.2.X |
| 2.1.0 | 2.1.1 |
| 1.6.0 | 1.6.0 |
| 1.5.1 | 1.5.2 |
| 1.4.5 | 1.4.2 |
| 1.3.0 | 1.3.2 |
Please file an issue. (Japanese forum is here.)
$ $ES_HOME/bin/plugin install org.codelibs/elasticsearch-dynarank/2.1.0
Create "sample" index:
$ COUNT=1;while [ $COUNT -le 100 ] ; do curl -XPOST 'localhost:9200/sample/data' -d "{\"message\":\"Hello $COUNT\",\"counter\":$COUNT}";COUNT=`expr $COUNT + 1`; done
100 documents are inserted. You can see 10 documents by an ascending order of "counter" field:
$ curl -XPOST "http://127.0.0.1:9200/sample/data/_search" -d'
{
"query": {
"match_all": {}
},
"fields": [
"counter",
"_source"
],
"sort": [
{
"counter": {
"order": "asc"
}
}
]
}'
DynaRank plugin is enabled if your re-order script is set to the target index:
$ curl -XPUT 'localhost:9200/sample/_settings?index.dynarank.script_sort.script=searchHits.sort%20%7Bs1%2C%20s2%20-%3E%20s2.field%28%27counter%27%29.value%28%29%20-%20s1.field%28%27counter%27%29.value%28%29%7D%20as%20org.elasticsearch.search.internal.InternalSearchHit%5B%5D'
$ curl -XPUT 'localhost:9200/sample/_settings?index.dynarank.reorder_size=5'
The above script is:
searchHits.sort {s1, s2 -> s2.field('counter').value() - s1.field('counter').value()} as org.elasticsearch.search.internal.InternalSearchHit[]
This setting sorts top 5 documents (5 is given by reorder_size) by a descending order of "counter" field, and others are by an ascending order.
Set an empty value to index.dynarank.script_sort.script:
$ curl -XPUT 'localhost:9200/sample/_settings?index.dynarank.script_sort.script='
DynaRank plugin provides a sort feature for a diversity problem. The sort script is dynarank_diversity_sort. The configuration is below:
curl -XPUT 'localhost:9200/sample/_settings' -d '
{
"index" : {
"dynarank":{
"script_sort":{
"lang":"native",
"script":"dynarank_diversity_sort",
"params":{
"diversity_fields":["filedname1", "filedname2"],
"diversity_thresholds":[0.95, 1]
}
},
"reorder_size":100
}
}
}'
diversity_fields is fields for a diversity. diversity_thresholds is a threshold for a similarity of each document.
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