elasticsearch filtering by the size of a field that is an array

Question

How can I filter documents that have a field which is an array and has more than N elements?

How can I filter documents that have a field which is an empty array?

Answer 1

Based on this: https://code.google.com/p/guava-libraries/source/browse/guava/src/com/google/common/collect/RegularImmutableList.java?r=707f3a276d4ea8e9d53621d137febb00cd2128da

And on lisak's answer here.

There is size() function which returns the length of list:

"filter" : {
    "script" : {
        "script" : "doc['fieldname'].values.size() > 10"
    }
}

Answer 2

javanna's answer is correct on Elasticsearch 1.3.x and earlier, since 1.4 the default scripting module has changed to groovy (was mvel).

To answer OP's question.

On Elasticsearch 1.3.x and earlier, use this code:

"filter" : {
    "script" : {
        "script" : "doc['fieldname'].values.length > 10"
    }
}

On Elasticsearch 1.4.x and later, use this code:

"filter" : {
    "script" : {
        "script" : "doc['fieldname'].values.size() > 10"
    }
}

Additionally, on Elasticsearch 1.4.3 and later, you will need to enable the dynamic scripting as it has been disabled by default, because of security issue. See: https://www.elastic.co/guide/en/elasticsearch/reference/1.4/modules-scripting.html