SOLR count multi valued fields query

问题

Is it possible to create a solr query where only documents are returned which have more than one entries in a multi valued field. For example:

docs: [
  {
    id: 1,
    myfield: ["hello word", "hello stackoverflow"]
  },
  {
    id: 2,
    myfield: ["hello word"]
  }
]

And my naive sample query just for explanation what I want:

/select?q=count(myfield.length, 'eq', 2)

回答1:

Yes it is but not "out of the box". A solution in order to achieve what you're looking for is to use CountFieldValuesUpdateProcessorFactory along with a new field called in your case myfield_count. For instance:

docs: [
  {
    id: 1,
    myfield: ["hello word", "hello stackoverflow"]
    myfield_count: 2
  },
  {
    id: 2,
    myfield: ["hello word"]
    myfield_count: 1
  }
]

After that you can simply use a boolean function in order to filter or score for myfield_count>1.

来源：https://stackoverflow.com/questions/38769405/solr-count-multi-valued-fields-query