Let's assume, I have the following documents in my index:
title: Entry #1
myfield: 5
---
title: Entry #2
myfield: 2
---
title: Entry #3
As you can see, myfield is optional and not present in all documents.
Now I want to select all documents where myfield is greater than 3 or the field does not exist. Of course there is also a search word let's say entry, so it finds all documents.
So the query should return Entry #1 and Entry #3.
Currently I am querying like this:
q=entry
defType=dismax
qf=title
fl=*
fq=-myfield:* myfield:[3 TO *]
which does not return any documents. Each filter query alone, so -myfield:* and myfield:[3 TO *] are working like expected.
How can I connect these two filter queries?
It's usually helpful to think of each term of the query as a set of documents, and the boolean operators as operations performed between these sets (i.e. AND finds the intersection between two sets, while OR finds the union). A negative set would then be the difference between sets.
When you use a negative match, you have to subtract it from something. When you don't have any other clauses in your query, Solr helpfully appends the complete set of documents (*:*) in front of your query. But as soon as you add a second boolean term, Solr can't do that any longer - since it doesn't know what you actually mean with your query.
So your negative clause needs to start with a set that the other set (i.e. the documents that doesn't have field) can be subtracted from:
fq=(*:* -myfield:*) OR myfield:[3 TO *]