Hybrid search with post-filtering
Introduced 2.13
You can perform post-filtering on hybrid search results by providing the post_filter parameter in your query.
The post_filter clause is applied after the search results have been retrieved. Post-filtering is useful for applying additional filters to the search results without impacting the scoring or the order of the results.
Post-filtering does not impact document relevance scores or aggregation results.
Example
The following example request combines two query clauses—a term query and a match query—and contains a post_filter:
GET /my-nlp-index/_search?search_pipeline=nlp-search-pipeline
{
"query": {
"hybrid":{
"queries":[
{
"match":{
"passage_text": "hello"
}
},
{
"term":{
"passage_text":{
"value":"planet"
}
}
}
]
}
},
"post_filter":{
"match": { "passage_text": "world" }
}
}
Compare the results to the results in the example without post-filtering. In the example without post-filtering, the response contains two documents. In this example, the response contains one document because the second document is filtered out:
{
"took": 18,
"timed_out": false,
"_shards": {
"total": 2,
"successful": 2,
"skipped": 0,
"failed": 0
},
"hits": {
"total": {
"value": 1,
"relation": "eq"
},
"max_score": 0.3,
"hits": [
{
"_index": "my-nlp-index",
"_id": "1",
"_score": 0.3,
"_source": {
"id": "s1",
"passage_text": "Hello world"
}
}
]
}
}