FlatObjectField will benefit from using IndexOrDocValuesQuery

[harshavamsi]

Is your feature request related to a problem? Please describe.
Similar to the efforts in #7057 and #11144, FlatObjectField has a bunch of MultiTermQueries that will benefit from being able to search documents when only doc_values is enabled and using IndexOrDocValuesQuery when it has both index and doc_values enabled.

Describe the solution you'd like
If only index is enabled, we return the existing query. If both index and doc_values are enabled we return a wrapped IndexOrDocValuesQuery. If only doc_values are enabled, we probably use SortedSetDocValuesField.newXyzQuery for range, fuzzy etc

Describe alternatives you've considered
Do nothing.

[harshavamsi]

@mingshl I created this issue to track the work for FlatObjectField.

[macohen]

@mingshl are you able to pick this up? If you're able, awesome, otherwise I think this should be unassigned or assigned to someone else.

[mingshl]

I have no problem picking this up. I saw a flat-object PR #11425 is up, and I would love to raise the new one after it's merged.

[msfroh]

Oh -- I think we can get this one "for free" if we address #11635

Basically, the two fields that make flat object work are both keyword fields, which have the IndexOrDocValueQuery optimizations. If flat object asks those fields to make their own queries, we'll get those optimizations.