What's the most efficient way to filter out items with member that don't contain the terms?

Question

What's the most efficient way to write the following query?

Get 5 items that have member member that contains any of these items: ['item1', 'item2'].

should: [{ terms : {member: ['item1', 'item2'] } }]

If you find only 3 items, get 2 more where member is empty.

How do I finish this query?

Answer 1

You can use a should clause with term and not exists. So it will fetch documents where field member matches input query and where field doesn't exist. You can pass size to get top 5 documents from result

{
  "size": 5,
  "query": {
    "bool": {
      "should": [
        {
          "terms": {
            "member": [
              "1",
              "2",
              "3"
            ]
          }
        },
        {
          "bool": {
            "must_not": [
              {
                "exists": {
                  "field": "member"
                }
              }
            ]
          }
        }
      ]
    }
  }
}