One other possibility is to create a second boolean field "has_terms" or something and just add an fq clause like "&fq=has_terms:false"....
On Thu, Jul 20, 2017 at 12:00 PM, Shawn Heisey <apa...@elyograg.org> wrote: > On 7/20/2017 7:20 AM, Hendrik Haddorp wrote: >> the Solr 6.6. ref guide states that to "finds all documents without a >> value for field" you can use: >> -field:[* TO *] >> >> While this is true I'm wondering why it is recommended to use a range >> query instead of simply: >> -field:* > > Performance. > > A wildcard is expanded to all possible term values for that field. If > the field has millions of possible terms, then the query object created > at the Lucene level will quite literally have millions of terms in it. > No matter how you approach a query with those characteristics, it's > going to be slow, for both getting the terms list and executing the query. > > A full range query might be somewhat slow when there are many possible > values, but it's a lot faster than a wildcard in those cases. > > If the field is only used by a handful of documents and has very few > possible values, then it might be faster than a range query ... but this > is not common, so the recommended way to do this is with a range query. > > Thanks, > Shawn >
