BoolFilter and BoolQuery in ElasticSearch

Question

I am applying to two search requests a filter and a query semantically identical like so:

static FilterBuilder filter(String field1Value, String field2Value){
    return FilterBuilders.boolFilter().must(FilterBuilders.termFilter("field1",field1Value)).should(FilterBuilders.termFilter("field2",field2Value));
}
static QueryBuilder query(String field1Value, String field2Value){
    return QueryBuilders.boolQuery().must(QueryBuilders.termQuery("field1",field1Value)).should(QueryBuilders.termQuery("field2",field2Value));
}
client.prepareSearch(indexName).setPostFilter(filter("hello", "world")).setTypes("mytype");
client.prepareSearch(indexName).setQuery(query("hello","world")).setTypes("mytype");

However, while the search with the query returns results, the search with the filter doesn't return any result. Aren't the two suppose to behave identically and if not, why?

Don't use PostFilter. It removes documents after the query stage. This is meant to remove documents after aggregating against some superset. You want to use the filteredQuery that contains your filter. — pickypg
– pickypg, Commented Jul 6, 2015 at 23:16
Thanks although I oversimplified. I am doing a filtered aggregation, is that a bad idea? — Edmondo
– Edmondo, Commented Jul 7, 2015 at 8:31
Filtered aggregation is a good use. You really just want to be sure that you really want to do a post filter. The other types of filters are harder to misuse. — pickypg
– pickypg, Commented Jul 7, 2015 at 14:02

keety · Accepted Answer · 2015-07-06 20:14:16Z

1

They are not exactly the same. In a bool query with a must clause a document would be a match if none of the clauses in should are matched provided there is no explicit minimum_should_match in the query.

In filter bool query at-least one should clause needs to be satisfied for a document to be considered a match. In filters there is no option of minimum_should_match and can be treated as always set to one.

i.e for filters it can be viewed as follows

 [must_clause] && [should_clause1 || should_clause_2]

For the example in the OP :

1) the documents would pass the filter if and only if they match field1 criteria in must clause and field2 criteria in should clause .

2) Whereas for bool query it would suffice for a document to be considered a match if must-clause is satisfied i.e field1 match

edited Jul 6, 2015 at 20:14

answered Jul 6, 2015 at 19:27

keety

17.5k4 gold badges53 silver badges58 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Edmondo Over a year ago

In both queries there's a must though?

Collectives™ on Stack Overflow

BoolFilter and BoolQuery in ElasticSearch

1 Answer 1

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related